Scholars' Mine
Doctoral Dissertations
Student Research & Creative Works
1971
Structure and properties of silver borate glasses
Edward Nashed Boulos
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STRUCTURE AND PROPERTIES OF SILVER BORATE GLASSES
by
EDWARD NASHED BOULOS, 1941-
A DISSERTATION
Presented to the Faculty of the Graduate School of the
UNIVERSITY OF MISSOURI - ROLLA
In Partial Fulfillment of the Requirements for the Degree
DOCTOR OF PHILOSOPHY
in
CERAMIC ENGINEERING
1971
Advisor
ll
PUBLICATION THESIS OPTION
This thesis has been prepared in the style specified
by the Journal of the American Ceramic Society. Pages 1-45
are submitted for publication in this
journal. Appendix E,
pages 78-85, was also submitted for publication in the same
journal. Appendices A,B,C,D and F have been added for the
purposes normal to thesis writing.
iii
ABSTRACT
Clear glasses form in the system Ag 2 o-B o 3 up to about
2
35 mol.%
(65 wt.%)
Ag 2 o. Infrared absorption,
thermal
expansion and density data indicated an analogy to the Na o2
B2o3 system. Pentaborate-triborate group pairs appear to be
formed upon the addition of Ag 2 o to B 2 o 3 up to 20 mol.% Ag 2 o
and diborate groups from 20 to 33 mol.% Ag 2 o. This interpretation is supported by the comparison of the infrared
absorption spectra of quenched and crystallized glasses.
One crystallization product ,Ag 2 0.4B 2 o 3 , has been identified
previously. A new compound starts to appear at 28 mol.% Ag 2 o
Silver is generally present as a network modifier like
sodium. This was substantiated by the comparison of the molar
volume of sodium and silver borate glasses. Above 27 mol.%
Ag o some atomic silver is assumed to be present. Below
2
15 mol.% Ag o exploratory studies indicate a two-phase struc2
ture within an immiscibility gap.
A low temperature internal friction peak in the glasses up
to 28 mol.% Ag o corresponds with the alkali peak in other
2
glasses; a high temperature peak appearing in the 34 mol.%
Ag o glass is associated with the appearance of non-bridging
2
oxygen in the system.
iv
ACKNOWLEDGEMENT
The author is deeply indebted to his advisor, Dr.
Norbert J. Kreidl whose capability and direction were major
factors in the accomplishment of this investigation.
Appreciation is also extended to Dr. Delbert E. Day for
his help and valuable suggestions.
Thanks are also expressed to the Ceramic Engineering
Department, University of Missouri-Rolla for providing the
equipments and facilities which made this research possible.
Gratitude is also extended to the Chairman of Chemistry
Department for his cooperation in allowing the use of the
Infrared Spectrophotometer.
The helpful discussion and assistance of Mr. M. Maklad
and Mr. J. Starling are also acknowledged.
The author is indebted to the National Science Foundation
for financial support during part of his program.
Also, my deepest thanks go to my wife, Mervet,
for her
encouragement and patience during the undertaking of this
study.
v
TABLE OF CONTENTS
Page
ABSTRACT.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ACKNO~vLEDGEMEl'JTS.
iii
•• . . • . • . . . . . . . . . . . . . • . . . . . . •. . . . . . • . . .
i v
LIST OF F I G U R E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
vii
LIST OF TABLES. . . • . . . . . . . . . . . . . . . . . . . • • • . . . • . . . . • . . • . . .
X
I.
INTRODUCTION...................................
1
II.
EXPERIMENTAL...................................
3
1.
Sample Preparation .. . . . . . . . . . . . . . . . . . . . . . . .
3
2.
X-Ray Diffraction Studies . . . . . • . . • . . . . • . . . .
3
3.
Thermal Expansion • . . . . . • • . . • • • • • • • • . • . . • . . •
3
4.
Infrared Absorption . . . . . • . . . • . . • . . . . . . . • . . .
4
5.
Density and Holar Volume . • . . • . . • . . • . . . . • . • .
4
6.
Internal Friction . . . . • . . . . . . . . • . . . . . . . . . . . .
5
RESULTS AND DISCUSSION.................. . . . • . • .
6
1.
Range of Glass Formation . . . • • . • • . . . . . • • • • • •
6
2.
X-Ray Diffraction and DTA. • . . . . . • . • . • • • • . • •
8
3.
Thermal Expansion. • . . . . • • • . • . . • • • . . . . . . . . . .
11
4.
Infrared Absorption . . . . • . • . . . • • • • . . • • . • • • . .
18
5.
Density, Molar Volume and Phase
Separation . . . . . . . . . . . . . . . • . . . . . . . . . . . . . • . . .
28
6.
Internal Friction . . • • • . . . . . . . . . . • . . • • . . . . . .
34
IV.
CONCLUSIONS • • . • . • . . . . . . . · • · · · · • · · · · · · · • · • · · • · · ·
39
V.
REFERENCES . . . . . . . . . . . . . . · . · · · · · · · · · · · · · · · · · · · · ·
VI.
APPENDICES • • • • . . . . · •. · • · · • · · · · · · · · • · · · · • · · · · · · ·
III.
41
46
A.
X-Ray Diffraction • • . . . . . . • . . . . . • . • • . • • • • . . .
47
B.
Thermal Expansion • • . . • • • • . • . • . . • . . • . . • . . . • .
53
vi
TABLE OF CONTENTS
(continued)
Page
C.
Infrared Absorption.. . . . . . . . . . . . . . . . . . . . . . .
55
1.
Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
2.
Pellet Technique For Infrared
Spectroscopy. . . . . . . . . . . . . . . . . . . . . . . . . . .
57
3.
Infrared Spectrophotometer . . . . . . . . . . . . .
58
4.
Literature Review of Infrared Studies
of Boric Oxide and Alkali Borate
5.
D.
E.
58
Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
61
5.1.
Semi-Quantitative Analysis . . . . . . . - 61
5.2.
Infrared Absorption . . . . . . . . . . . . . .
65
Density Measurements . . . . . . . . . . . . . . . . . . . . . . .
74
1.
Theory................................
74
2.
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
Mixed Cation Effects in Silver Borate
Glasses....................................
78
Internal Friction . . . . . . . . . . . . . . . . . . . . . . . . . .
86
VITA . . . . . . . . . . . . . . . . . . . . . . . . · . · · . . · · · · · . · . . . . . ·
88
F.
VII.
Glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
vii
LIST OF FIGURES
Page
Figure No.
X-ray diffraction patterns of two devitrified silver-borate glasses . . . . . . . . • . . . . . . . .
9
2
DTA curves of two silver-borate glasses . . . .
10
3
Typical thermal expansion curves of silverborate glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Coefficients of thermal expansion for silver-borate glasses as a function of cornposition...................................
l4
Thermal expansion of lithium, silver, and
sodium borate glasses in the 1:4 composition range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
Transformation and softening temperatures,
Tg and Ts, of silver-borate glasses as a
function of composition . . . . . . . . . . . . . . . . . .
17
Infrared spectra of sodium, lithium, and
silver-borate glasses in the 1:4 composition range. . . . . . . . . . . . . . . . . . . • . . . . . . . . . . .
19
Infrared spectra of Ag 0.4B 2 o 3 glass before and after devitrificatlon . . . . . . . . . . .
20
Infrared spectra of Ag 0.2B 2 o 3 glass before and after devitrificatlon . . . . . . . . . . .
22
10
Infrared spectra of B20 3 glass compared
with low silver content glass . . . . . . . . . . . . . .
23
11
Infrared spectra of sodium and silver
borate glasses before and after devitrification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
Infrared spectra of sodium and silver
borate glasses in the 1:2 composition
range . . . . . . . . . . . . . . . . . . . . . · · . · · · · · · · · · ·
12
13
The borate groups . . . . . . . . . . . . . . . . . . . • . . . . . .
26
14
Variation of density and molar volume of
silver and sodium borate glasses as a
function of cornposi tion . . . . . . . . . . . . . . . . . . • .
29
1
4
5
6
7
8
9
12
viii
LIST OF FIGURES
(continued)
Figure No.
15
16
17
Page
Variation of denstiy with composition
in wt.% for silver-borate glasses.......
Transmission electron micrograph of glass
containing 13 mol.% Ag o, mark indicates
2
31
5000 ° A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
Internal friction for XAg 0-(lOO-X) B o
2
2
glasses; frequency 0.5 Hz . . . . . . . . . . . . . . .3 . . .
35
Effect of increasing Ag20 on x-ray diffraction patterns of XAg 2 o. (l00-X)B 2 o 3 glasses.
48
X-ray diffraction patterns of devitrified
silver-borate glasses................. . . . . .
49
x-ray diffraction patterns of devitrified
silver-borate glasses . . . . . . . . . . . . . . . . . . . . . .
50
Comparison of the 'd' values of Ag 2 0.4B 2 o 3
in single crystals and devitrified glass ...
51
APPENDIX A
l
2
3
4
APPENDIX B
1
Thermal expansion curves of silver borate
glasses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
54
APPENDIX C
l
2
Effect of increasing Ag 2 o on the intensity
of B0 4 and Ag 2 o bands. Lx Ag 2 0· (100-x)
.B o
glasses] . . . . . . . . . . . . . . . . . . . . . . · · · · · · · ·
2 3
Effect of increasing Ag 2 o on the fourco-ordination of boron. [xAg 2 o· (100-x)
glasses] . . . . . . . . . . . . . . . . . . · · . · · · · · · · · ·
63
Effect of increasing Ag 2 o on the intensity
of the B0 bands. [xAg 2 0· (l00-x)B 2 o 3
4
qlasses] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64
n o
2
3
62
3
ix
LIST OF FIGURES
(continued)
Figure No.
4
5
6
7
8
Page
Effect of increasing Ag o on the
2
infrared transmittance of XAg o.
2
(100-X) B o
glasses . . . . . . . . . . . . . . . . . . . . . . . . .
2 3
Effect of increasing Ag o on the
2
infrared transmittance of XAg o.
2
( 100-X) B o
glasses • . . . . . . . . . . . . . . . . . . . . . . . .
2 3
66
67
Effect of increasing Ag o on the infrared
2
transmittance of XAg o. (l00-X)B o
devit2
2 3
rified glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
68
Effect of increasing Ag 0 on the infrared
transmittance of XAg o.tlOO-X)B o
devit2 3
2
r i fie d g 1 as s e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
69
Effect of increasing Ag o on the infrared
2
transmittance of
XAg o. (l00-X)B 2 o 3 devit2
rified glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70
Infrared transmittance curves of Ag 2 o and
H BO
crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
3
71
l
Internal friction curves for (l-x)Ag 2 o.
xNa o.4B o
glasses; frequency 0.5 Hz . . . . . . .
2 3
2
82
2
Internal friction curves for (1-x) Na 2 o.
xAg 0.4B o
glasses; frequency 0.5 Hz . . . . . . .
2 3
2
83
3
Internal friction curves for (l-x)Ag 2 o.
xcu 0.4B o
glasses; frequency 0.5 Hz . . . . . . .
2 3
2
84
9
APPENDIX E
X
LIST OF TABLES
Page
Table I. Composition and color of silver-borate
glasses...................................
Table II. Coefficients of thermal expansion,
transformation and softening temperatures,
density and molar volume data............
7
12
Appendix F
Table I. Temperature and height above back-ground
for low and high temperatures oeaks,in the
xAg o. (100-x)B o glasses . . . . . . . . . . . . . . . . .
2 3
2
87
1
I.
INTRODUCTION
Silver is a constituent of special glasses which have
unusual properties and applications; knowledge of these
glasses is limited to studies or researches motivated by
special objectives.
However, because of the documented
or potential function of silver in photo-chromic, photosensitive, dosimeter and semiconductor glasses, extensive
studies have been made on glasses in which traces of silver
have been incorporated.
The state of silver in these glasses
has been studied by several researchers.
that if a small amount of silver oxide
Weyl(l)
(0.1% Ag 2 o)
stated
is introduced
into silicate glass, Ag+ ions participate in the glass structure in a fashion similar to that of Na+ ions due to the
similarity of their charge and size.
Silver however, has a
much lower ionization energy than sodium and,
is more easily reduced.
ments(2'3'4)
therefore,
Electron spin resonance experi-
have shown that the silver ion, Ag+, is capable
of trapping both types of charge carriers, electrons as well
.
.
h
1
.
A+,+,+
as holes, becom1ng e1ther t e neutra spec1es g
or Ag
respectively.
(The notations +,- and +,+ symbolize the possi-
bility that the environment of Ag+ is maintained in the
electronic process).
In this respect, silver does not seem
to behave very differently from many transition ions, for
instance, iron or cerium.
Previous studies on the solubility of silver in glasses(
showed dependence upon oxygen pressure, melting temperature
2 5 6
' ' )
2
and composition of the base glass.
It is difficult to melt
silicate glasses containing appreciable amounts of silver
due to their high melting temperature.
On the other hand,
substantial amounts of silver may be diffused into silicate
glasses, in which case silver presumably replaces sodium.
Westermann(?) obtained a silver aluminosilicate with 22%
Ag
2
o by melting kaolin with silver in an oxidizing atmos-
phere.
Also, relatively large amounts of silver (Ag/P ratio
of 1), can be introduced during the melting of phosphate
glasses (S).
The purpose of this work was to study the structure and
properties of silver borate glasses containing significant
amounts of silver.
3
II.
(1)
EXPERIMENTAL
Sample Preparation:
The raw materials were certified reagent grade:
silver
nitrate, boric acid, sodium carbonate, and lithium carbonate.
The weight of each batch ranged from 40-70 grams.
The batch
materials were carefully ground, mixed and then melted in
alumina crucibles for 60-80 minutes in an electric furnace
under a normal atmosphere.
The alumina crucible was pre-
heated to temperatures ranged between 800 to 1000°C,
small
charges were made at a time and, to assure homogeneity,
the melt was stirred several times prior to each charge and
after the completion of charging.
Glasses were annealed at
temperatures ranging from 350-450°C and stored in blackwalled desiccators.
(2)
X-Ray Diffraction Studies:
A General Electric XRD-5 diffractometer with a copper
target and nickel filter was used to obtain the diffraction
patterns of powdered samples of both the glasses and the
corresponding devitrified glasses.
To induce crystallization the glass samples were heated
at temperatures ranging from 500-580°C for a period of 100
hours.
The temperature of crystallization was determined by
DTA technique.
(3)
Thermal Expansion:
The thermal expansion was determined from room
temperature to the softening temperature of each glass.
An Orton Automatic Recording Dilatometer, with HR-100
x-y recorder, was used for this purpose.
Rods 2(+0.002)
inches
4
long with parallel ends were prepared, annealed, and then
used for these measurements.
minute.
The heating rate was l°C per
The method given by Green(g)
for the evaluation
of the coefficient of thermal expansion, transformation and
softening temperatures was used.
The parameters are evaluated
from plots of the thermal expansion versus temperature as
in fig.
3 where the slope of the line AB determines the
coefficient of thermal expansion, the intersection AB-BC gives
the glass transformation temperature at point B; and point
c
is the softening temperature, which is the temperature at
which the rod shows first signs of sagging.
(4)
Infrared Absorption:
Infrared absorption of all glasses and corresponding
devitrified samples was measured in the
2.5~
to
using a 337 Perkin-Elmer infrared spectrometer.
25~
range
Samples were
prepared using both the film and KBr pellet techniques.
Com-
parison was made between the spectra of the silver borate
glasses and lithium or sodium borate glasses of the same
composition ratio, as well as between the glass and the correspending devitrified sample.
(5)
Density and Molar Volume:
Density was measured using the suspended-weight method
based on the Archimedes principle.
Xylene -- whose density
had been carefully measured -- was used as the immersion liquid.
The samples were weighed on a Sartorius semi-micro balance
enclosed in a constant temperature box, the tenperature being
controlled at 25.6°C for all samples, with an accuracy of + 0.1°C.
5
The samples were suspended by a fine tungsten wire 0.08 mm.
ln diameter.
Densities were computed from equations described
in detail elsewhere(lO).
Corrections were made for the
immersed and unirnrnersed parts of the suspended wire in xylene
and air respectively as well as for the force due to surface
tension.
Three well annealed, bubble-free samples from
different batches of the same composition were measured separately and the average of their densities taken.
3
error in each measurement was + 0.0005 g/cm .
The maximum
[see Appendix D]
Density data was used to calculate the molar volume of
all glass samples by using the molecular weight of the glasses
in terms of x Ag o.
2
(6)
(1-x) B 2 o 3 .
Internal Friction:
Internal friction was measured from -180°C to 250°C
using an inverted torsion pendulum operating at about 0.5
Ilz.
The apparatus and theory used in the internal friction
2
and activation energy measurements are explained elsewhere(l ).
Fibers approximately 0.5 rnrn. in diameter were drawn from the
melt, annealed at the proper annealing temperature for 20
minutes, then cooled slowly to room temperature.
6
III.
(1)
RESULTS AND DISCUSSION
Range of Glass Formation:
Clear glasses were obtained in the system, xAg
o.
2
Metallic
(100-x)B 2 o , were x ranged from 0 to 35 mol.%.
3
silver was precipitated in the crucible for glasses containing
more than 25 mol.%;
35 mol.% Ag 2 o was the maximum amount of
silver incorporated into the glass; introducing higher percentage into the batch always resulted in precipitation of
This metallic silver accounts for the
metallic silver.
difference between batch and analytical compositions in the
However,
high silver containing glasses shown in Table I.
the
analysis does not account for the water content which, in
b orate glasses,
.
lS
9( 11)
on the order of 0.1 to 0.5 wt.o.
.
The glasses were hygroscopic, especially those rich in B 2 o 3 ,
becoming cloudy at the surface.
Those rich in Ag
2
o became
dark and developed a mirror-like layer on the surface after
exposure to light for several hours.
This mirror-like layer
(2, 13)
.
.
.
t
h as been reported by var1ous 1nvest1ga ors
.
1
an d e 1 ec t r1ca
conductivity measurements have shown that the films are
metallic in nature(
14 15
'
).
However, glasses kept in black-
walled desiccators showed no change in color for several
months.
All glasses so prepared contained no crystals detectable
by x-ray diffraction.
The diffuse x-ray diffraction bands
for all glasses look alike.
[see Appendix A]
7
TABLE I
Glass
No.
Ag?O Content
Mol.%
I'>Jt.%
Analysis
Mol.%
Color
1
1
3.3
2
2
6.4
3
5
14.9
4
7
20.0
"
5
10
27.0
"
6
13
33.2
7
15
37.0
8
17
40.5
9
19
43.9
10
20
45.4
11
22
48.4
12
25
52.6
13
27
55.2
14
30
58.8
28.61
15
33
62.1
30.21
16
36
65.2
34.07
17
40
68.9
34.29
TABLE I.
Colorless
"
4.88
II
II
Light Yellow
II
Golden Yellow
19.16
II
II
24.56
II
Brownish Red
"
II
Dark Brown
II
Composition and Color of Silver-Borate Glasses
8
(2)
X-Ray Diffraction and DTA:
The x-ray diffraction patterns of devitrified samples
in the composition range 5 to 27 mol.% Ag 2 o showed crystals
of Ag 2 0·4B 2 o as the predominant phase
3
(fig. la).
This is
the only compound in the silver-borate system identified in
it was first recognized by De-Carli(l 6 ) and
the literature:
then by Willis and Hennessy(l 5 ) from studies on partial molar
free energy and heat content curves; single crystals of this
compound were prepared and identified by Krogh-Moe(l 7 ) using
x-ray techniques.
Glasses containing 28 to 34 mol.% Ag 2 o showed a new
type of diffraction pattern after heat treatment
(fig.
lb).
This pattern is characterized by peaks at the following 28
angles in the order of decreasing intensity:
36.4, 35.6, 21.3, 29.8, 32.7, 38.7, 43.4.
17.9, 27.6, 31.2,
It was not possible
to identify the corresponding compound by using the ASTH
Similar diborate
cards.
compounds have been found in both lithium and sodium borate
systems and infrared results
(section III 4)
indicate that
lithium and silver borate glasses in the 1:2 composition range,
contain the diborate network.
The DTA curves for two glasses containing 20 and 28
o are shown in fig. 2 as curves a and b respectively.
2
The exothermic peak beginning at 520°C with a maximum at
mol.% Ag
555°C (curve a)
could correspond to the formation of the Ag 2o.
o compound. Curve b shows a formation temperature of
2 3
about 580°C, with an exothermic peak at 620°C, which could be
4B
attributed to the compound Ag 2 0·2B 2 o 3 postulated by x-ray.
>t-(/)
z
w
MOL. 0/o Ag20
z-
(b) 30 (GLASS NQ 15)
t-
0
w
0
~
0
()
(a) 20 (GLASS NQ 10)
w
~
70
60
50
40
30
20
10
DEGREES, 2 9
Figure 1.
X-ray diffraction patterns of two devitrified silver-borate glasses.
~
MOL. 0/o Ag20
u
-~
0:::
w
:::c
~
0
X
w
l
100
200
300
400
500
600
700
800
TEMPERATURE, °C
Figure 2.
DTA curves of two silver - borate glasses.
f-J
0
11
The x-ray radial distribution for this system compared
with the synthetic ideal peak is under investigation(lB).
This study on a glass containing 20 mol.% Ag
2
o
the oxygen-oxygen distances are 2.3 and 3.0 A 0
cation-cation distances are 5.4 and 6.9 A 0
(3)
showed that
while the
,
•
Thermal Expansion:
Figure 3 shows typical thermal expansion curves for
four silver borate glasses.
Similar curves were obtained
for the other glasses in this series ranging from 0 to 35
rna 1.% Ag
2
o.
Table I I contains the coefficients of expansion
as well as the dilatornetric transformation and softening
temperatures
(T
g
,T
s
) •
Like those of other alkali borate glasses, the coefficients of thermal expansion of the silver borate glasses
showed a distinct minimum at about 15 mol.% Ag 2 o
Silver borate glasses,
(fig.
4).
in general, show coefficients of
expansion higher than those of the corresponding lithium
borate glasses but lower than those of the corresponding
sodium borate glasses.
A plot of the thermal expansion
versus temperature of the lithium,
sodium,
and silver
borate glasses containing 20 mol.% is shown in fig.
6
thermal expansion coefficients are 7.5 x 10- ,
5.
9.0 x 10-
The
6
and
8.2 x 10- 6 crn/crn/°C for lithium, sodium, and silver borate
glasses,
respectively.
Data for the B
o
2 3
glass obtained here
using the rod-dilation method agree with the results of
Green( 9 ), Sarnsoen(l 9 ), and Jankal( 2 0)
who used other methods.
12
TABLE II
Glass
No.
B203
2
Coeff. of
therm. Exp.
cm/cm/°C
16.0xl0
-6
15.2xlo- 6
Trans.
temp.
Tg °C
Sof.
Temp.
Ts oc
210
220
Density
g/cm3
+ 0.0005
Molar Vol.
cm3
260
1.8460
37.71
275
1.9094
37.31
2.1459
36.22
3
4
10.7xl0
5
9.0xl0
-6
-
260
300
2.3216
34.87
295
330
2.5300
33.92
6
2.8245
32.11
8
3.1193
31.80
3.3112
30.41
3.4022
30.90
3.6516
29.96
13
3.6525
30.04
14
3.8142
30.40
10
8.2xl0
-6
-6
370
400
11
12
9.5xl0
15
11.5xl0
16
12.3xl0
TABLE II.
-6
-6
-6
370
395
360
380
4.0395
29.35
350
370
4.3082
29.71
Coefficients of Thermal Expansion, Transforma-
tion and Softening Temperatures, Density and Molar Volume Data.
l3
0.6
z
0
en
z
<!
a..
X
w
0.5
_J
0.4
<!
~
a:::
w
~ 0.3
B
a:::
<{
w
z
0.2
_J
~
z
w
(.)
0.1
0::
w
a..
A
o~~--~----~------._------~
100
200
300
400
TEMPERATURE, °C
Figure 3.
Typical thermal expansion curves
of silver-borate glasses.
14
..._
z
18r-------T-------~------~---------
LLJ
-LL.
( .)
LL.
LLJ
0
(.)
z
0
en
z
~
<.0
w
0
><
_J
(.)
<(
0
X
~
a::
w
::c
..._
'
~
(.)
'~
(.)
0:::
<(
w
z
_J
z
<(
LLJ
~
10
Figure 4.
20
30
40
Coefficients of thermal expansion for
silver-borate glasses as a function of
composition.
15
In agreement with Krogh-Moe( 2 l)
and Uhlmann( 22 ), we
find that the minimum in the expansion coefficient observed
in this study, as well as in other alkali borate studies
canno t
• d b y th e orlglna
• •
1 Warren hypothesls
• (23 I 24)
b e exp 1 alne
which assumes saturation in the formation of tetrahedral
Bo
4
units.
The behavior of these thermal expansion curves,
which has always been associated with the term anomalous,
does not give any clues on the association of Bo
Krogh-Moe( 2 l)
4
tetrahedra.
and Uhlmann( 22 ) gave an acceptable qualitative
explanation for the broad minima in the thermal expansion
curves, namely, that they are due to a competition between
the formation of B0
4
tetrahedra, tending to decrease the
expansion coefficient, and the introduction of modifying
cations, tending to increase it.
More quantitative studies
are needed to explain the thermal expansion behavior.
The transformation and softening temperatures as functions
of the Ag o content are shown in fig.
2
6.
There is a rapid
rise in both curves with Ag 2 o addition up to 20 mol.% Ag 2 o
where they go through a maximum, to decrease with higher
20 ) and Green (g) found that ""Ja 0 B 0
Jankel (
Ag o content.
2 - 2 3I
2
Bao-B o
and K o-B o
glasses behaved similarly.
2 3
2
2 3
The variations in Tg and Ts as shown in fig. 6 indicate
l'
that the introduction of Ag 2 o produces a more rigid structure
with a corresponding increase in T g and T s .
The maximum
shown in the Tg curve at 20 mol.% Ag 2 o may correspond to the
congruent melting point of the Ag 2 o-4n 2 o 3 compound, the existence
Such a
of which is confirmed by x-ray and DTA analyses.
16
0.6
z
I- Li 0 · 4 8 0
0
(/)
z
0.5
_J
0.4
~
X
w
<(
2
2 3 GLASS
2- Ag 2 o · 4 8 2 0 3 GLASS
3- Na 2 o · 4 8 0 GLASS
2 3
:E
a::
w
..._
I
0.3
a::
w
<(
z_J
..._
z
w
u
a:
w
a.
0.2
0.1
100
200
300
400
500
TEMPERATURE, °C
Figure 5.
Thermal expansion of lithium,silver and
sodium borate glasses in the 1:4 composition
range.
17
500,------;.-----~------~---------
400
u
0
Tg
w
0:::
:::::>
~
0:::
w
a.. 200
:E
w
1-
1000
10
20
MOL.
Figure 6.
30
40
0
/o Ag 2 0
Transformation and softening temperatures,
T and T , of silver-borate glasses
g
s
as a function of composition.
18
correlation between the variation of T
and the shape of the
g
liquidus in the phase diagram has been noted before by Hyers
and Felty( 25 ).
(4)
Infrared Absorption:
Figure 7 shows the infrared spectra of sodium,
and silver tetraborate glasses from 4-25
~·
lithium,
As is seen from
the figure the absorption for silver borate glass is remarkably similar to that for the other alkali borate glasses.
A complete assignment of infrared absorption bands to the
fundamental modes of vibration has been made for alkali
borate glasses by different authors( 26 , 27 , 28 , 2 9,30).
Figures 8 and 9 show the considerable resemblance
between the infrared spectra of two silver borate glasses
and the corresponding devitrified glasses.
Figure 10 corn-
pares the spectrum of B 2 o 3 glass with that of a glass of
low silver content.
shown in figs.
The three different types of spectra
8, 9, and 10 represent the spectra of all
glasses containing 0 to 35 mol.% Ag 2 0.
Figure 10 represents
the infrared spectra of the low silver content glasses up
to 7 mol.% Ag o, fig.
2
Ag 2 o and fig.
8 shovvs glasses between 10 to 25 mol.%
9 shows the high silver content glasses.
As
expected, a pronounced breading is exhibited in the spectrum
of the glass compared with that of the corresponding devitrified sample, since in the glass the individual groups no
longer have identical surrounding.
Figure 11 compares the infrared spectra of devitrified
sodium and silver tetraborate glasses.
The same similarity
has been demonstrated for all other glasses in this series.
WAVE LENGTH, MICRONS
4.0
5.0
~
6.0
8.0
\\1
w
u
z
10.0
15.0
20.0
1- No 20 · 48 20 3 GLASS
2- Ll20 · 48203 GLASS
3- Ag20 · 4 8 20 3 GLASS
\\ \
-
9.0
._~
-::E
en
z
<t
a::
._ I
(8 LOWN THIN FILMS)
2500
2000
15001300 1200 1100
1000
900
800
700
600
500
400
FREQUENCY, cm- 1
Figure 7. Infrared spectra of sodium,lithium and silver-borate glasses in the 1:4
composition range.
1--'
1.0
WAVE LENGTH, MICRONS
5.0
4.0
,,
--
6.0
,
......
',
0~
',
BEFORE HEAT TREATMENT
GLASS NQ 10
AFTER HEAT TREATMENT
Ag 20 · 48 20 3
\
\
w
'
\
~
\
\
()
z
\\
<t
.__
\
I
I
I
I
\
\
I-
-
\
I
\
I
I
I
I
\
',
::E
'
(/)
'
z
<t
0::
.__
8.0
'
' ' ',
I II
' ' , __ ..., ,--i..._~
\
'
\
\
\
\
\
\
\
'
I
I
I
(KBr PELLET)
2500
2000
1000 900
800
700
600
500
400
FREQUENCY cm- 1
Figure 8.
Infrared spectra of Ag 20.4B 2o3 glass before and after devitrification.
tv
0
21
Krogh-Moe
(30)
has also found a strong resemblance in the
infrared spectra of sodium borate and the corresponding
lithium borate glasses and crystals.
In 1938, Hibben( 3 l)
observed that the Raman spectrum of borax is very similar
to that of anhydrous sodium diborate glass; he concluded
that the structures of these phases must be related.
Since
the structure of borax is known to consist of polyions
where 50% of the boron atoms are fourfold coordinated,
Hibben's results indicated that these polyions condense without losing their identity to three-dimensional networks
when borax is dehydrated and fused to a glass.
On such a
basis, Krogh-Moe( 32 ) proposed his valuable group model
for the structure of alkali borate glasses.
[see Appendix C]
The foregoing results and discussions enable us to
suggest that the boron-oxygen network in silver borate glasses
is similar to that of sodium and lithium borate glasses in
the same molar composition range.
The bands appearing at 800, 1053, 944 ern
the dotted curve in fig.
of the so
4
to
group
-1
shown as
8, are characteristic vibrations
( 2 9)
.
.
; these bands develop on the addltlon
32
In agreement with Krogh-Moe's(
)
o
n 2o 3 .
2
assumption that the structural model for boron oxide
of Ag
glass is a random three-dimensional network of B0 3 triangles with a comparatively high fraction of six-membered
boroxol rings( 33 ),
(fig. 13 a), these bands can be explained
as being due to the formation of triborate groups and pentaborate groups
(fig. 13, band c).
The absorption bands at 885,
WAVE LENGTH, MICRONS
4.0
5.0
--
9.0
8.0
6.0
20.0
- - - AFTER HEAT TREATMENT
,
Ll.J
u
I
z
~
I
I
I
/
I
I
....~
I
,I
I
I
C/)
I
z
I
I
I
I
<t
0::
....
(KBr PELLET)
2500
\ \
2000
I
' ,,_ . . . f/
25.0
------- BEFORE HEAT TREATMENT
GLASS NQ. 15
Ag 20 · 28 20 3
~
15.0
10.0
I
II
1500 1300 1200
/
/
I
I
I
I
I
I
I
I
I/ ,
\I
\
',,,
... ... ,
1100
--.... ___ ...... .,~
1000
900
~~
I
I
I
II
I
'
' ' ._/I
,~/
.,..1
800
700
600
500
400
FREQUENCY em -I
Figure 9. Infrared spectra of Ag 20.2B 2o3 glass before and after devitrification.
(\,)
(\,)
WAVE LENGTH, MICRONS
5.0
4.0
*-
-....,
w
~
.__
15.0
10.0
',
I
I l
I I
I
,I
\
(/)
z
..... ,
',',
_,,
/
I'
I
1
I
~'
I
/'
/
-
, ... I
'-
1//
/
/
\
a::
(K Br PELLET)
2000
,.-
I
~"-..
',
<t
2500
'
'I
I
...., ..,
-,
25.0
.,
I
\
20.0
I
I
-~
.....
9.0
------- GLASS NQ 3
Ag 20 ·198 20 3
B2o3 GLASS
.......
u
z
8.0
6.0
',. . , ~
,,
/
II ,.,,.
..
~ ~------.--
1500 1300 1200
1100
1000 900 800
700
600
500 400
FREQUENCY em -I
Figure 10.
Infrared spectra of B o glass compared with a low silver content glass.
2 3
!\.)
w
WAVE LENGTH, MICRONS
4.0
~
......,
5.0
1- Na 20 · 4 8 20 3 AFTER HEAT TREATMENT
2-Na 0·4B 20 3 BEFORE HEAT TREATMENT
'- ...,
2
...........
........
'
''
'
''
\
\
\
''
~
"''
\\
w
z
\\
(.)
\
~
'
\\
'\
I-
\
\\
\
I
' '
~
J I
, ,, - - , I II
\
I
~/
'
\
', \
I
',
,.- -..{
....... ...._,//
I
\
f'l.
I ..............
I
\
\
',
\ I
\.,..,
'----...
I
I
I
..._/
3- Ag20 · 4 8203 AFTER HEAT TREATMENT
(K Br PELLET)
2000
I
I
I
I
\
\
I
31~1I
\
I
\
I
' \~~4
I
l
'\
I
z<(
a::
..,_
2500
f\
,,,
I I \
I
I
'
en
\
\
\
-~
' ', 2
4- Ag 20 · 48 20 3 BEFORE HEAT TREATMENT
1500 1300 1200
1100
1000
FREQUENCY, em -I
900
800
700
600
500
400
1\)
*'"
Figure 11. Infrared spectra of sodium and silver borate glasses before and after devitrification
WAVE LENGTH, MICRONS
5.0
4.0
-- '
~
0
,""
,,
,,....
,"",,..
, - .....
6.0
\
\
I
25.0
J' I I I
I
I
I
I
I
r/
I
I
\
\
\
\
\
\\
(/)
\
z
0:::
20.0
\
:;E
I-
15.0
10.0
\
\
\
I-
<(
9.0
\
\\
\
w
(.)
z
~
8.0
Na 20 · 2 8 20 3 GLASS
------ Ag 20 · 2 8 20 3 GLASS
,\
\\
7.0
\
\
\
'
(K Br PELLET) ~
2500
2000
1500 1300 1200 1100
1000
900
800
700
600
500
400
FREQUENCY, cm- 1
Figure 12.
Infrared spectra of sodium and silver borate glasses in the 1:2 composition
range.
I\)
Ul
(a)
(b)
(c)
(d)
BOROXOL
PENTABORATE
TRIBORATE
DIBORATE
• BORON ATOM
0 OXYGEN ATOM
Figure 13. The borate groups.
N
""
27
719 and 1250 ern
-1
correspond to the
v
1
,
v
2
and the doubly-
degenerate v 3 vibrations characteristic of the Bo units( 29 ).
3
The assignment of fundamental bands to the triborate and
pentaborate groups is found to be a complex task, since the
individual fundamentals appear to merge into broad bands
mainly due to the interaction between these groups( 3 , 4 ).
This increase in the B0 4 groups on the addition of alkali oxide
to about 33 mol.% was confirmed by NMR studies( 35 ).
NMR, also,
showed that there are two types of B0 3 groups present from
10 to 30 mol.% alkali oxide; these could arise from forma-
tion of the triborate and pentaborate groups suggested by
Krogh-Moe( 34 ).
X-ray study(l 7 ) of the crystalline silver tetraborate,
Ag o-4B o , suggested that i t consists of two separate,
2
2 3
identical, three-dimensional, interlocking networks, each
network being composed of triborate and pentaborate units
which have been found previously in anhydrous cs 2 0·3B 2 o 3 and
.
(34)
K 0·5B o
respect1vely
.
The spectra shown in figs. 7,
2 3
2
9, and 11 thus prove that this borate network present in
the crystalline silver tetraborate is the same for silver
and sodium borate glasses, as well as their crystals in the
1:4 composition range.
The infrared spectra of the silver borate glasses and
corresponding devitrified samples in the composition range
27 to 35 mol.% Ag o, shown in fig.
2
9, were found to resemble
spectra of the anhydrous crystalline Li 2 0·2B 2 o 3 studied by
Krogh-Moe< 34 ) who found them to consist of diborate units.
28
This suggests the presence of such diborate group in silver
glasses
(fig. 13d) within the given composition range.
Figure 12 compares the spectra of Ag 0·2B o and Na 0·2B o
2
2 3
2
2 3
glasses, and suggests that the borate network of the two
glasses in this composition range is the same; in other
words, they both contain the diborate units.
The infrared absorption spectra of the silver borate
glasses show the
2.9~
and the
3.13~
bands due to structural
and surface water respectively, the amount of which is
expected to be approximately in the range given by Stevels
et al. ( ll) .
These ranges are from 0.40 to 0.25 wt.% H o
2
for the structural water and from 0.50 to 0.20 wt.% H o for
2
the surface water for glasses containing up to 20 mol.% Na o.
2
However, for higher alkali content, up to 28 mol.% Na o
2
there is no indication in the infrared spectra of the presence
of surface water, while the structural water ranges from
about 0.25 to 0.10 wt.% H 2 o.
As the Ag 2 o content is raised
beyond 30 mol.% the water bands begin to increase again.
It
should be taken into consideration that hydrogen bonds play
an important part in the atomic arrangement of the borate
glasses, especially glasses of low alkali contents< 25 , 27 , 28 ).
(5)
Density, Molar Volume, and Phase Separation:
Plots of density versus composition for silver borate
glasses are shown in fig. 14, together with comparable sodium
.
(36)
borate glasses measured by Sp1nner et al.
• Both series
of glasses were melted in air, their water content is
reported in sec. III.
4.
29
4.5
Ag 2 0- 8 2 0 3 GLASS SYSTEM
- - - - Na 2 0- 8 2 0 3 GLASS SYSTEM(AFTER SPINNER et. al.)
39
4.0
3.5
r()
3.0
35
rn
E 2.5
()
-<---
'
C)
~
_
--
_,
w--
34 ~
::::>
_J
33 0
>
J-
~
<!
(f)
z
w
0
§
_J
0
1.5
31
:E
1.0
29
0.5
F~gure
14. Variation of density and molar volume of silver
and sodium borate glasses as a function of
composition.
30
Figure 15 shows the variation in density with composition in wt.% for the silver borate glasses.
Shaw and Uhlmann( 37 >
have recently postulated that the compositional regions whose
density-weight per cent composition plots show smooth, positive curvature, with no extreme or inflections can be regarded as those compositions most likely to phase-separate.
Figure 15 shows that the presenceofanirnrniscibility region
in the Ag 2 o-B 2 o system is likely.
3
The change in the molar volume of glass as a function
of composition was used by several authors as a tool(JB)
for
studying the distributions of different ions in the glass
network.
Figure 14 shows this relation for silver borate
glasses compared with that for sodium borate glasses found
in the literature( 36 ).
The decrease in molar volume for
both silver and sodium borate glasses shown in fig.
14 may
be explained on the basis that the addition of Na 2 o or Ag 2 0
to
B o3
increases the proportion of
2
result in a more compact structure.
modifier ions
(Na + and Ag + ) ,
Bo 4
units, which will
In addition,
these
take interstitial positions ln
the network resulting in a large increase in mass but only
a slight increase in volume.
These two effects can thus
result in a sharp decrease in the molar volume.
The lower rate of decrease in molar volume of the
silver borate glasses which starts at about 27 mol.% Ag 2 o
may be attributed to the presence of higher amounts of the
uncharged atomic silver.
31
rt)
E
~
~
~
t-
en
z
w
Cl
2
'o
10
20
30
40
50
60
WT. 0/o Ag20
Figure 15.
Variation of density with composition,
in wt.%, for silver-borate glasses.
32
Electron microscope investigations of silver borate
glasses indicated a two phase structure similar to that
found in lithium and sodium borate glasses by Shaw and
39
Uhlmann(
).
The extent of this immiscibility in different
alkali borate glasses was reported as 2 to 18 mol.% for
o-B 2 o 3 glass, 2 to
2
2 to 16 mol.% for Rb 0-B o
Li 2 o-a 2 o 3 glass, 7 to 24 mol.% for Na
22 mol.% for
x 2 o-B 2 o 3
glass,
2
glass and 2 to 20 mol.% for cs 2 o-a 2 o
glass.
3
2 3
To explore the
Ag 2 o-B 2 o 3 glass system three glasses containing 7, 13, and
20 mol.% Ag 2 o were examined by direct transmission electron
microscopy.
A square-edged diamond file was used to file
flakes from a fresh surface prepared by breaking the sample
just before viewing under the electron microscope.
A fresh
surface is important because of the possible reduction of
surface silver due to light exposure.
A detailed description
of the technique and equipment used is discussed elsewhere( 4 0).
All glasses before heat treatment and the heat-treated glass
containing 20 mol.% Ag 2 o showed a single phase structure.
The heat-treated glasses containing 7 and 13 mol.% Ag 2 o
showed a two-phase structure.
Figure 16 shows the submicro-
structure of the 13 mol.% Ag 2 o glass which was held for two
hours at 430°C and etched with dilute nitric acid for six
seconds; the same type of microstructure was found for the
glass containing 7 mol.% Ag 2 o.
No crystallization or change
in color was observed after heat treatment for the two glasses
that showed phase separation.
The particle size of the Ag 2 o-
a2o3 glasses is comparable with that of Li 2 o-B 2 o 3 and Na 2 o-B 2 o 3
33
Pigure 16 . Transmission electron micrograph
of glass containing 13 mol.% Ag 2 o,
mark indicates 5000 °A.
34
glasses and much smaller than that of the
Rb 2 o-B 2 o
3
and Cs 2 o-B 2 o glasses.
3
Glasses containing up to 25 mol.% Ag o fluoresced
2
under uv radiation.
Enough atomic silver is probably
present to account for this fluorescence( 2 ).
At compositions
higher than 25 mol.% Ag 2 o fluorescence quenching occurs
due to the aggregation of atomic silver.
All the silver glasses on heat treatment or exposure
to light for a long time, suffer reduction of Ag ions to atomic
(metallic) silver which in turn tends to aggregate causing
the disappearance (quenching) of fluorescence even in the
low silver containing glasses.
Similar effects have been
observed in silicate glasses containing traces of silver( 2 ).
(6)
Internal Friction:
Internal friction curves for binary silver borate
glasses in the composition range 10 to 35 mol.% Ag 2 o are illustrated in fig. 17.
Glasses containing 10 to 30 mol.%
o have one peak in the temperature range -180 to 250°C;
2
the peak height increases with increasing silver concentra-
Ag
tion.
Increasing the silver content decreases the peak
41 ' 4 2 )
.
temperature, in analogy to the behav1or
o f a lk a l 1. b orate (
and silicate glasses( 44 ).
In general, however, the inter-
nal friction peaks of silver borate glasses are at a much
lower temperature than those of the corresponding alkali
(41)
.
borate glasses
.
This behavior is due to the h1gh
mobility of silver ions in glasses.
Electrical conductivity
studies( 45 ) have shown that silver ions have a higher mobility
than the alkali ions.
9~~----~--~~----~----~--------~
-------X = 10
8
rt)
-----X = 15
0
,...
)(
'\
'o
I
I
---X= 20
-- ----- X = 28
X = 34
I 1I
I
'
I I"' \
''
I \
\ I
\ /"'-..
\ I
I
.
I
I,,,
\
~
z
0
-.....
u
-a::
1
I '
I
\
I
l
LL..
~
,
0::
_/
w
'
___ _...... ,..,.,.,..___
I___ . A....... ,________
.....
h 1,'
/
/ I 'I
)< ..../
/:
..
I
··"" /
_,
--
/
'
......__/ ..
\' ./'
z
I
I'
'\.
\
)';--/>·
_J
<[
I
I
At'
I ,,,
/
......
~"
;'j
/
"'
X Ag 20 · ( 100 -X) 8 20 3
z
0'
I
I
I
I
-100
I
I
I
I
-.
I
I
I
I
I
.-.I
I
TEMPERATURE, T
Figure 17. Internal friction for xAg
2
I
I
I
I
- I
I
I
1
1
I
oc
o. (100-x)B 2o3 glasses;
frequency 0.5 Hz.
w
lll
36
The activation energy calculated from internal friction
o was
2
found to equal 22.2 K cal./mol., as compared with the lit-
measurements of the glass containing 15 mol.% Ag
erature value of 32.0 K cal./ mol. for the corresponding
sodium borate glass( 46 ).
A second peak at a higher tenperature lS observed in
the glass containing 34 mol.% Ag 2 o shown in fig.
17.
A
similar peak is found in the alkali silicate glasses and
is usually attributed to the nonbridging oxygens present
in the glass( 44 ) or to the interaction between alkali ions,
bridging H+ ions and nonbridging oxygens( 42 , 43 ).
The
presence of nonbridging oxygens together with the OH group
is offered as the explanation for the high temperature peak
of glasses containing 34 mol.% Ag
2
o, since N.M.R. ( 35 ) and
other studies showed that nonbridging oxygens start to form
around a composition of 33 mol.% alkali oxide and all these
glasses contain appreciable amounts of water.
The absence of the second peak in the silver or alkali
borate glasses containing less than 33 mol.% reported in this
.
study and ln
t h e 1'lterature (41,42,46)
.
d on
cou ld b e exp 1 alne
the assumption that the nonbridging oxygen is either not
present or present in such low concentration as to be undetectable by internal friction.
The absence of the non-
bridging oxygen peak was noticed in the aluminosilicate
glasses with an aluminum to alkali ratio of one, in these
glasses i t is generally postulated that the addition of
alumina to the alkali silicate converts the nonbridging oxygen
37
ions to bridging ones< 47 ).
Also, fig.
17 shows no additional peaks as would be
expected in the high silver content glasses; such peaks
could occur due to relaxation process between atomic silver
and the network.
The absence of additional peaks in the
internal friction curves could be explained as due to one
of two facts:
either atomic silver is present in very
small concentration, or the internal friction peak due to
these mobile silver atoms lies at a much lower temperature
than the temperatures studied here.
To check the effect
of atomic silver on the internal friction curves, a glass
containing 34 mol.% Ag 2 o was exposed to uv and visible
radiations for a long period of time until reducing more
Ag+ to atomic (metallic) Ag 0
brown to black.
,
thus changing its color from
An identical internal friction curve is
reproduced with no additional internal friction peaks.
Internal friction studies on mixed sodium silver borate
glasses< 48 ) showed similarity to the mixed alkali silicate
glasses< 12 ).
This suggests that silver plays the role of a
second alkali in these glasses.
[see Appendix E]
From the preceding discussions, i t is seen that silver
borate glasses behave in a fashion similar to that of the
alkali borates.
The appearance of the nonbridging oxygen
peak in the internal friction curve for glasses containing more
than 33 mol.% Ag 2 o is an additional proof for the Krogh-Moe
group model( 34 ) which was also supported by NMR( 3 S) studies
and which suggests the continuous formation of the B0 4 group
38
on the addition of alkali oxide to B 2 o until 33 mol.%
3
alkali oxide is reached.
39
IV.
CONCLUSIONS
In the binary silver-borate system, glasses were formed
within the composition range of 0 to 35 mol.%
(65 wt.%)
Infrared absorption, thermal expansion, density,
molar volume, and internal friction studies indicated that
in these glasses Ag 2 o plays a role similar to that of Na o
2
and other alkali oxides.
Thus, the addition of Ag o to
2
B
o
2 3
appears to result in the formation of pentaborate-
triborate group pairs up to 20 mol.% Ag 2 o.
Ag
2
At 20 mol.%
o the structure would consist mainly of two interpene-
trating networks of alternating pentaborate and triborate
groups, and from 20 to 33 mol.% Ag 2 o of diborate groups.
This interpretation is supported by the similarities between
the x-ray spectra of the devitrified glass and those of the
crystals in the 1:4 composition range, and between the
infrared spectra of quenched and devitrified silver and
sodium borate glasses.
X-ray and DTA studies suggested the presence of a new
compound, Ag 0-2B o , which starts to appear at 28 mol.% Ag 2 o.
2 3
2
A two-phase structure appeared in the silver borate
glasses containing less than 15 mol.% Ag 2 o as indicated by
electron microscope and density studies.
An internal friction peak, corresponding to the alkali
peak was produced on the addition of Ag 2 o to B 2 o 3 up to 28
Glasses containing 34 mol.% Ag 2 o showed a second
peak at a higher temperature, which is associated with the
appearance of nonbridging oxygen in the system.
40
The change observed in the molar volume curve and
the fluorescence quenching which occurred at compositions
higher than 25 mol.% Ag 2 o indicated the presence of some
atomic silver in the high silver containing glasses.
41
V.
REFERENCES
G.E. Rindone and TiJ.A. vJeyl,
(1)
"Glasses as Electrolytes
in Galvanic Cells," J. Amer. Ceramic Soc.,
W.A. Weyl,
( 2)
Tech . ,
29
~>J.
( 3)
( 13 5 )
A. Weyl,
J. Phys. Chern.,
(4)
"Silver in Glasses:
2 91-3 8 9 T
57 pp.
91-95
(1950).
J. Soc. Glass
( 19 4 5) .
753-756
(1953).
"Diffusion of Silver in Glass,"
J.Z. Electrochem, 42 pp.
(5)
(3)
"Metals in the 1\tomic State in Glasses,"
0. Kubaschewski,
1936,
II,"
33
5-7
(1936).
(Brit. Chern. Abs. A.
281).
G.M. Willis and F.L. Hennessy,
"The System Ag 2 o-B o ; its
2 3
Thermodynamic properties as A Slag Hodel," Trans. A.I.M.E.,
19 7 pp.
(6)
13 6 7
( 19 53) .
T. Maekawa, T. Yokokawa and K. Niwa,
Ag o in Na o-B o
2
2
681
(1969).
(7)
2
3
"Solubility of
Melts," Bul. Chern. Soc. Japan,
V.I. Westermann,
42 pp.
677-
"Uber die Aufnahme von Silberoxyd
durch Oxyde und Oxydver bindungen bei hoheren Temperaturen,"
J.Z. Anorg. Allgem. Chern., 206 pp.
(8)
E. Lell and N.J. Kreidl,
97-112,
(1932).
"Radiation Effects on Complex
Glasses," Proc. Cairo Solid State Conf., 1966, Ed. A. Bishay,
Plenum Press, New York,
(9)
R.L.
Green,
(1966).
"X-Ray Diffraction and Physical Properties
of Potassium Borate Glasses," J. Amer. Ceram. Soc., 25
83-89
(1942).
(2)
42
(10)
P.M. Vora,
"Imperfections in the Ag-In System and Lattice
Parameters of Cadmium Oxide," M.S. Thesis, U.M.R.
(11)
(1970).
F.C. Everstein, J.M. Stevels, and H.I. Watermann,
"The Density and Refractive Index of Vitreous Boron and
Sodium Borate Glasses as Function of Compsoition," J.
and Chern. Glasses, 1
(12)
(4)
123-133 (1960).
J.E. Shelby and D.E. Day,
Mixed-Alkali Silicate Glasses:
Soc., 52
(13)
(4)
"Mechanical Relaxations in
I, Results," J. Amer. Ceramic
169-174 (1969).
K.H. Sun and N.J. Kreidl,
"Coloration of Glass by
Radiation," Glass Ind., 33 pp. 590
(14)
Phys.
G.E. Rindone,
(1950).
"The Spontaneous Growth of Silver Films
on Glasses of High Silver Content," J. Soc. Glass Tech.,
37 pp. 124 T (1953).
(15)
B.I. Markin,
"Electrical Conductivity of Argenta-Boric
Glasses," J. Gen. Chern.
(16)
(U.S.S.R.), 11 pp.
285-292
(1941).
F. DeCarli, "Anhydrous Berates of Silver, Barium, and
Zinc," Atti. Accad. Lincei, 5
(6)
41-47
(1927); Cited from
Chern. Abs., 21 pp. 1771 (1927).
(17) J. Krogh-Moe, "The Crystal Structure of Silver Tetraborate," Acta Cryst., 18 pp.
77
(1965).
(18)
E.N. Boulos, M. Hydlar, and N.J. Kreidl, To Be Published.
(19)
M.U. Samsoen,
"Anomaly in the Expansion of B 2 o 3 Glass,"
Compt. Rend., 181 pp. 354
(20)
E. Janckel,
(1925).
"Temperature of the Transformation Intervals
of Glasses Formed from B 2 o with Na 2 o and BaO," Z. Elektrochem.,
3
40
(76)
541 (1934); Ceramics Abs., 14 (6)
137
(1935).
43
( 21)
J. Krogh-Moe,
"The Relation of Structure to Some
Physical Properties of Vitreous and Molten Borates," Arkiv
Kemi., 14 pp. 553
(22)
(1959).
D.R. Uhlmann and R.R. Shaw,
"The Thermal Expansion of
Alkali Borate Glasses and the Boric Oxide Anamoly," J. Non.
Cry s t .
( 2 3)
So 1 . , 1
(5)
B. E. Warren,
347- 359
( 19 6 9 ) .
"Summary of Work on ."1\tomic Arrangement
in Glass," J. Arner. Ceram. Soc., 24
( 2 4)
(8)
256-261
(1941).
J. Biscoe and B.E. Warren, "X-Ray Diffraction Study
of Soda-Boric Oxide Glass," J. Arner. Ceramic Soc.,
pp.
(25)
287-293
21
(8)
(1938).
M.B. Hyers and E.J. Felty,
"Structural Characteriza-
tions of Vitreous Inorganic Polymers by Thermal Studies," Mat.
Res. Bull., 2 pp. 535-546
( 2 6)
(1967).
S. Anderson, R.L. Bohon, and D.D. Kimpton,
"Infrared
Spectra and Atomic Arrangement in Fused Boron Oxide and
Soda Borate Glasses," J. Amer. Ceramic Soc.,
38
(10)
370-377
(1955).
(27)
P.E. Jellyman and J.P. Procter, "Infrared Reflection
Spectra of Glasses," J. Soc. Glass Tech.,
39 pp.
173-192 T
(1955).
(28)
H. Moore and
P.~-J.
McMillan,
"Study of Glasses Consisting
of the Oxides of Elements of Low Atomic Weight:
Glass Tech., 40 pp.
(29)
II," J.
Soc.
97-138 T (1956).
R.V. Adams and R.W. Douglas,
"The Absorption of Infrared
Radiation and The Structure of Glasses," Glastech. Ber. V,
International Glass Congress Heft VII pp. 12-24
(1959).
44
(30)
J. Krogh-Moe, "The Infrared Spectra of Some Vitreous
and Crystalline Borates," Ark. Kemi, 12 pp. 475
(31)
J.H. Hibben,
"The Constitution of Some Boric Oxide
Compounds," Arner. J. Sci., 35
(32)
(1958).
J. Krogh-Moe,
(5)
113-135
(1938).
"New Evidence on the Boron Co-ordination
in Alkali Borate Glasses," J. Phys. Chern. Glasses,
1-6
3
(1)
(1962).
(33)
J. Krogh-Moe,
"The Structure of Vitreous and Liquid
Boron Oxide," J. Non. Cryst. Sol., 1
(34)
J. Krogh-Moe,
(4)
269-284
(1969).
"Interpretation of the Infrared Spectra
of Boron and Alkali Borate Glasses," J. Phys. Chern. Glasses,
6
(2)
(35)
46-54
(1965).
P.J. Bray and J.G. O'Keefe, "NMR Investigations of
.Alkali Borate Glasses," J. Phys. Chern. Glasses, 4
(36)
(2)
37
(1963).
L. Shartsis, W. Capps, and S. Spinner, "Density and
Expansivity of Alkali Borate Glasses," J. Arner. Ceramic Soc.,
36
(2)
(37)
35-43
(1953).
R.R. Shaw and D.R. Uhlmann,
"Effect of Phase Separation
on the Properties of Simple Glasses: I," J. Non. Cryst. Sol.,
1
(6)
(38)
474-:-498
(1969).
A.M. Bishay and M. Maklad, "Radiation Induced Optical
Absorption in Lead Borate Glasses in Relation to Structure
Changes," J. Phys. Chern. Glasses, 7 (5)
(39)
149-156
(1966).
R.R. Shaw and D.R. Uhlmann, "Subliquidus Inuniscibility
in Binary Alkali Borates," J. Amer. Ceramic Soc.,
377-382
(1968).
51 (7)
45
( 4 0)
M.S. Maklad and N.J. Kreidl,
"Some Effects of OH
groups on Sodium Silicate Glasses," Proc. IX International
Congress on Glass, To Be Published in Sept. 1971.
(41)
V.H. Karsch and E. Janckek,
"Theoretrische and Jl1echanische
Untersuchungen an Alkaliboratesglas," Glastechn. Ber., 34
Jahrg., Heft 8 pp.
(42)
M. Coenen,
597-903.
(1961).
"Mechanical Relaxation of Silicate Glasses
with Eutectic Composition," Z. Electrochem,
65
(10)
903-908
(1961).
(43)
H. Coenen, "Influence of Anisotropy
on the Relaxation
of Silicate Glasses and General Systematic of Damping Maxima
in Glasses," Phy. of Non-Cryst. Sol., Proc. of International
Conf., Delft, July
( 4 4)
(1964), pp.
445-60.
R.J. Ryder and G.E. Rindone,
"Internal Friction of
Single Alkali Silicate Glasses Containing Alkaline Earth
II,"
Oxide:
( 4 5)
J. Amer. Ceramic Soc., 44
B.I. Markin,
H.
J. Phys.
( 4 7)
DeWaal,
pp.
532-537
(1961).
"Electrical Conductivity of Argenta-Boric
Glasses," J. Gen. Chern.
( 4 6)
(ll)
(USSR)
ll, pp. 285-292,
(1941).
"On the Boric Oxide Anaornaly in Nabal Glasses,"
Chern. Glasses, 10
(3)
101-107 (1969).
D.E. Day and W.E. Steinkamp,
"Mechanical Damping Spec-
trum for Mixed Alkali R 0.Al o .6sio 2 Glasses," J. Amer.
2 3
2
Ceramic Soc., 52
( 4 8)
(ll)
571-574
(1969).
E.N. Boulos and N.J. Kreidl,
"Hixed Cation Effects 1n
Silver Borate Glasses," Submitted for Publication in the ,J.
Amer. Ceramic Soc.
46
VI.
APPENDICES
47
APPENDIX A
X-Ray Diffraction
Figure
(1)
shows the x-ray diffraction patterns for the
Ag 2 o-B 2 o 3 glasses in the composition range 0 to 35 mol.% Ag
As is seen in this figure,
2
o.
the diffuse x-ray patterns for all
glasses in this series are alike.
Figures
(2 and 3)
show the x-ray patterns for the
Discussion
d ev1"t r1"f"1e d g 1 asses, heated 100 hours at 550 °~.
c
of the results shown in these figures are found in section III.2.
Figure
(4)
gives a comparison of the 'd' values of
devitrified Ag 0.4B o glass and those of the compound Ag 2 0.4B 2 o 3
2
2 3
computed from Krogh-Moe's paper
(1 )
.
48
Mol.% Ag 2 0
35
:>-!
E-1
H
30
U)
z
li:l
E-1
z
H
Cl
J:il
Cl
20
0::
0
u
~
70
50
60
40
30
20
10
DEGREES, 2 e
Figure 1.
Effect of increasing Ag 2 o on the
x-ray diffraction patterns of
xAg
2
o.
(100-x)B 2 o
3
glasses.
Mol.% Ag 0
2
23
:>t
8
H
U}
z
rLI
8
zH
0
rLI
5
0
~
Figure 2.
30
20
10
DEGREES,26
X-ray diffraction p0tterns of devitrified silver-borate glasses.
ol:::.
\.0
Mol.% Ag 0
2
34.5
~
e-c
H
Ul
34
z
r:q
e-c
zH
0
r:q
~
0
0
~
50
40
30
DEGREES,
Figure 3.
20
2e
X-ray diffraction patterns of devitrified silver-borate glasses.
10
Ul
0
51
-
-
(Y")
(Y")
..-...
0
~N ~
.
~
0
E-1
U)
>;
NP::
tJI
.:X:
u
Q)
U)
U)
.:X:
0
1-
N....:l
0
~
~
I
0
tJI
0
H
N
tJI
.:X:
-
~
t...9
. 8.
~
..c:
-
-
H
>
J:il
·-
Q
-
-
Ul
0
-
--
,_
-
---:.......:::
-·-
Figure 4.
-
-
(Y")
-
values of
Comparison of the 'd'
Ag o.4B o single crystals and
2 3
2
devitrified glass.
1-
N
.:X:...
52
REFERENCES FOR APPENDIX A
(1)
J.
Krogh-Moe,"The Crystal Structure of Silver Tetra-
Borate," Acta Cryst., 18 pp.
77
(1965).
53
APPENDIX B
Thermal Expansion
Figure
(1)
shows a typical thermal expansion curve
for some silver-borate glasses.
The compositions of the
corresponding glass numbers shown in this figure are listed
on page
( 7 ).
54
0.7r-----~------~------~--------~--------~
X=O.O
0.6
X=7
§
0.5
H
(f)
~
P-1
:X:
~
H
~
0.4
~
::r:
E-1
p::
~
~
zH
X=28
0.3
H
E-1
z
~
up::
~
~
X=lO
0.2
0.1
0
500
100
TEMPERATURE,
Figure 1.
0
c
Thermal expansion curves of silver
borate glasses.
55
APPENDIX C
Infrared Absorption
1.
Theory
The study of infrared absorption spectra in glasses
can give much information about their structural building
units.
These structural units have natural vibrational
frequencies which correspond to wavelengths in the 5-100
~
region of the spectra.
Spectra in the infrared region
arise from the absorption of definite quanta of radiation
as a result of transitions between certain vibrational or
rotational energy levels.
Transitions between vibrational
energy levels within the same electronic level give rise to
spectra in the near infrared region, while spectra in the
far infrared region arise from transitions between rotations
within the same vibrational level.
An isolated assembly of
N atoms can have as many as 3N-6 different fundamental modes
of vibration.
These normal modes are due to either a change
in bond lengths (stretching) or angle (bending)
of the mole-
cule; they appear as fundamental bands and are characterized
by high intensities and sharpness. All general vibrational
motions which a molecule may undergo can be resolved into
either one or a combination of these normal modes.
However,
not all transitions between different energy levels are
infrared-active.
There are two selection rules restricting
the activity of such transitions:
a)
In order for molecules to absorb infrared radiation
as vibrational excitation energy, there must be a change in
56
the dipole moment of the molecule as i t vibrates.
Therefore,
any change in direction or magnitude of the dipole during a
vibration gives rise to an oscillating dipole which can
interact with the oscillating electric field component of
the infrared radiation giving rise to the absorption of this
radiation.
b)
which 6n
For a harmonic oscillator, only transitions for
= +1 can occur, where n is the vibrational or
rotational quantum number.
the transition from state n
frequency".
The frequency corresponding to
0
to n
1
is called the "fundamental
However, since most molecules are not perfect
harmonic oscillators, this selection rule breaks down and
transitions corresponding to 6n
=
+2 and +3 do occur.
Such
transitions are referred to as the "first" and "second"
overtones.
In crystalline compounds atoms have both short range
and long range order.
The lattice vibrations of the surround-
ing atom will affect the normal frequencies characteristic
of a certain point group.*
Sharp, well resolved bands are
characteristic for crystalline lattice vibrations.
In the vitreous state, where long range order is absent,
the asymmetry caused by the random arrangement of the vitreous
* All molecules can be classified into one or other of the
point groups.
Each point group is a collection of all the
symmetry operations that can be carried out on a molecule
belonging to this group.
57
network will change the dipole moment. Accordingly,
vibrations that are normally infrared-inactive in the case
of the isolated structural groups, become active in the
vitreous state. Furthermore, since any small variation in
the surroundings of a group affects a shift in the fundamental
frequencies,
the randomness of the network, where structural
units do not have entirely identical surroundings as they
do in the crystalline lattice,
leads to broadening and
overlapping of the absorption bands.
2. Pellet Technique For Infrared Spectroscopy:
The KBr pellet technique(l, 2 )was used to prepare the
samples for infrared study.The glass samples were first ground
to a fine powder in an agate mortar. The powder was then
sieved
(200-360 mesh)
to insure uniformity of particle size.
Each pellet consisted of 1% glass powder, the rest being
spectroscopic KBr powder; a total weight of approximately 0.2
grams gave a suitable pellet thickness. The weighed powders
were thoroughly mixed, then placed in a die and kept under
vacuum for 15 minutes, and finally a pressure of 20,000 lbs
was applied.
The pellets thus prepared were transparent.
Other techniques for sample preparation are:
a)
b)
Very thin films ( 3 ) (blown as bubbles from molten glass).
4
Diluted fine powder in oil (Nujol) suspension( ).
58
3.
Infrared Spectrophotometer:
The infrared absorption curve was obtained by placing
the transparent pellet in a Perkin Elmer 337, infrared
double beam grating spectrophotometer.
to
25~
or 4000cm
-1
to 400crn
-1
the range from 2.5~ to 8.33~
other from
4.
7.5~
to a
5~
).
(Ranges from
2.5~
One grating operates in
(4000cm-l to 1200cm- 1 ) and the
(1333cm
-1
to 400cm
-1
).
Literature Review of Infrared Studies of Boric Oxide
and Alkali Borate Glasses.
Several attempts have been made to interpret the
infrared spectra of boron oxide and binary alkali borate
glasses.
Krogh-Moe( 5 ) recently reviewed infrared studies
He proposed that the best structural model
for boron oxide glass is a random three-dimensional network
of Bo -triangles with a comparatively high fraction of six3
membered rings (boroxol rings) ; this model has been supported
{6)
recently by the x-ray study of Warren and coworkers
.
Anderson, Bohon and Kimpton(?) measured the infrared
absorption spectra of a series of Na 2 o-B 2 o 3 glasses.
They
stated that as Na o was added to the B 2 o glass, the number
2
3
After a cornof B0 tetrahedra and B-0-B linkages increased.
4
position of 15% Na o was reached, the atomic arrangement
2
They concluded that the hydrogen bonds
changed decidedly.
play an important part in the atomic arrangement of the
glass of low sodium oxide content.
59
8
Jellyman and Proctor( ) measured the infrared reflection spectra of a series of binary borate glasses
in the wavelength region
1-15~.
Their analysis was made
by observing the change and appearance of new bands in
o to
2 3
They confirmed the hypothesis that all the
the spectra in the composition range from pure B
additional oxygen atoms, from the addition of Na
2
o, are
accomodated by the formation of boron tetrahedra until onefifth of the boron atoms are tetrahedrally co-ordinated.
Additional oxygen atoms are thereafter accomodated as nonbridging oxygen ions.
9
Moore and McMillan( ) studied the infrared spectra of
different alkali borate glasses, and assigned certain frequencies to modes of B0 3 and Bo 4 groups.
by Anderson et al, (?)
As in the study
the spectra obtained by Moore and
McMillan showed serious water contamination evident from
the appearance of a strong OH stretching frequency in their
spectra at about
3~.
Adams and Douglas(lO)assigned the B0
4
and B0
to the Td and n 3 h point groups respectively.
of the fundamental bands for B0
3
and B0
4
3
units
The frequency
groups are given in
the following table:
B0
B0 4
3
\)1
11.3~
(885 ern
\)2
13.9~
( 719cm
\)3
-1
-1
6.9~
(1449cm
8.0~
(1250cm
)
\)1
9.5~
)
-1
-1
12.5~
)
)
\)3
10.6~
(800cm
-1
(1053cm
(944cm
)
-1
-1
)
)
60
Other bands in the infrared spectra of borate glasses were
attributed to overtones or combinations, or to the presence
of water in the glass.
Moore and McMillan( 9 ) observed a
displacement of the modes of vibrations of
Bo 3
lower frequency when an alkali oxide was added.
groups to
This was
attributed to the development of a more open type structure
due to the replacement of the original B0
3
groups by B0
4
groups.
Krogh-Moe( 4 ,ll) presented a group model for the
structure of alkali borate glasses based mainly on the infrared study of the glasses and a series of anhydrous
Ll. 0.2B o (13) ,
2
2 3
These compounds are
characterized by the presence of pentaborate, diborate,
triborate and pentaborate-triborate groups respectively.
These borate groups are shown in fig.
13 page (26).
From the analogy of the infrared spectra of alkali
borate glasses and those of the corresponding crystalline
compounds, Krogh-Moe
(15)
deducted that the structure of
these glasses consists of two interpenetrating networks.
In pure boron oxide glass these networks are built up of
boroxol groups.
The addition of one molecule of alkali
oxide to boron oxide results in the formation of one triborate group and one pentaborate group, which tend to occupy
adjacent positions in the network.
The formation of tri-
borate-pentaborate pairs continues upon further alkali addition until a concentration of 20 mol.% alkali oxide is
61
approached.
At 20 mol.% the structure consists mainly of
two interpenetrating networks of alternating pentaborate
and triborate groups.
The diborate groups presumably start
to form even before the 20 mol.% composition is reached.
On further alkali additions, the number of diborate groups
will increase at the expense of the pentaborate pairs.
At
33 mol.% alkali oxide, the glass will mainly consist of an
The number
interpenetrating network of diborate groups.
of boron atoms in fourfold co-ordination (NB
04
)
is given by
the equation:
X
NB04
= 100-X
where X is the molar percentage of alkali oxide; this equation is obeyed up to 33 mol.% alkali oxide.
6
Krogh-Moe model is supported by NMR(l ) and other
studies.
5.
Data
5. 1.
Semi-Quantitative Analysis:
Many of the bands characteristic of Ag 2 o (700,880,
1050, 1450 ern -1 ) overlap with most of those of boron (B0 4
and B0 ) ; i t was thus necessary to restrict the semi3
quantitative studies to the singlet frequency of B0 4
(v
of
1
at 800 crn-l), to the triply degenerate frequencies
Bo cv at 944 ern
-1
4 3
characteristic of Ag
) , and to the absorption at 535 em
-1
o. This ratio between the optical
2
densities at 944 crn-l and 535 crn-l versus mol.% Ag 2 o is
shown in fig.
(1).
Two maxima are observed in the curve
at about 20 and 33 mol.% Ag
2
o;
there is a continuous increase
't'J
1::
't:l
1::
..0
..0
co
.'<3'H
0
l1l
.........
.......
0
8
u
tJi
~
.........
.......
I
3
8
u
'<:!'
'<:!'
1.[)
0'\
1.[)
E-i
8
~
~
("'")
~
E-i
H
H
(/)
(/)
Q
Q
zrr.:J
~
H
H
H
8
8
0
0
u
p.
2
~
E-i
zrr.:J
4
N
...-1
...-1
I
co
......
1
~
u
p.
0
5
10
15
20
25
30
35
MOL.% Ag 2o
Figure 1.
Effect of increasing Ag 2o on the intensity of B0 group
4
and Ag 2o bands. [ xAg 2o. (100-x)B o glasses]
2 3
0'\
1\)
1.0
'0
!:!
cu
~I=
.........
0. 8
r-1
I
E;
0
oq<
oq<
0\
8
F:!!
~
8
lu J
"''
0.6
8
F:!!
~
8
H
H
(J)
(J)
Q
Q
0. 4
zj:ij zj:ij
~ ~u
u
H
H
8
8
0
0
~
0.2
~
0
Figure 2.
5
10
15
20
25
30
35
MOL.% Ag 0
2
Effect of increasing Ag 2o on the four-co-ordination of
boron. ( xAg o. (100-x)B o glasses]
2
2 3
0'1
w
64
Q)
lJ")
(Y')
.s::
..j...l
lH
0
?1
..j...l
•.-I
0
(Y')
U)
~
Q)
..j...l
U)
Q)
·.-I
~
U)
U)
Q)
....-!
Ctj
lJ")
N
.s::
..j...l
0
0
N
(Y')
N
~
.
H
dP
0
tJ>
::E:
~
0
0
N
tJ>
~
tJ>
0
N
m
X
I
0
0
....-!
~
·.-I
lJ")
U)
....-!
Ctj
Q)
,._,
0
~
0
.
N
tJ>
~
·.-I
lH
U)
0
'd
..j...l
0
Q)
lH
lH
~
.
(Y')
Q)
,._,
0
N
::l
tJ>
·.-I
~
s::
Ctj
.0
-.::t'
0
m
65
in
Bo 4
concentration until the composition of 33 mol.%
Ag 2 o is reached.
of
Bo 4
at 944 ern
between
Bo 4 I
Also the ratio between the optical density
-1
to
at 944 ern
Bo 3
-1
at 1250 ern
to
Bo 4 II
showed maxima around 20 mol.% Ag
2
-1
1
fig.
at 800 ern
o.
(2), and
-1
1
fig.
(3),
The maxima observed
o may indicate
2
the formation of a compound at this composition.
This has
in figs.
(11 2 and 3)
around the 20 mol.% Ag
been confirmed by x-ray and D.T.A.
The first part of fig.
(3)
study as shown in section III 2.
shows a decrease in the
This may be explained as being due to
an increase in the number of non-bridging oxygen in the
group region.
B0
Also, the increase in this ratio at corn-
positions higher than 25 mol.% Ag
2
o may be due to an in-
crease of the diborate groups at the expense of a decrease
in the pentaborate-triborate groups.
This hypothesis has
been tested by other authors for different glasses(l?).
5. 2.
Infrared Absorption:
Figures
( 4 and 5)
sho\<7 the infrared absorption of
some silver borate glasses which were investigated in the
composition range 0 to 35 mol.% Ag 0 1 and which were not
2
Figures (6, 7 and 8) are the
shown in section III 4.
infrared spectra of the corresponding devitrified glasses.
Figure (9)
show the infrared absorption spectra for
4
2.5
3.0
5.0
WAVE LENGTH, MICRONS
6.0
8.0
9.0 10.0
15.0
20.0 25.0
.......
dP
ril
u
~
8
8
H
~
{f)
~8
000
3500
Figure 4.
3000
1500
1200 1100 1000
FREQUENCY, CM-l
700
600
500 400
Effect of increasing Ag 2o on the infrared-transmittance of
xAg o. (100-x)B 2o glasses.
2
3
0'\
0'\
WAVE LENGTH, MICRONS
2.5
3.0
5.0
6.0
8.0
9.0
10.0
15.0
20.0 25.0
GLASSES
o\O
........
X
rr:l
u
~E-t
E-t
H
~
(/)
~E-t
4000
3500
Figure 5.
3000
1500
1200 1100 1000 900
FREQUENCY, CM-l
800
700
600
500 400
Effect of increasing Ag 2o on the infrared-transmittance of
xAg o. (l00-x)B 2o glasses.
3
2
0'1
"-l
WAVE LENGTH,
MICRONS
2.5
DEVITRIFIED GLASSES
dP
ril
u
~
8
8
H
::8
U)
~8
4000
3500
Figure 6.
3000
1500
1200 1100 1000 900 800 700 600 500
FREQUENCY,CM-l
Effect of increasing Ag 2o on the infrared-transmittance of
400
xAg 2o. (100-x)B 2o3 devitrified glasses.
"'
co
WAVE LENGTH, MICRONS
2.5
3.0
5.0
6.0
8.0
9.0
10.0
15.0
20.0 25.0
DEVITRIFIED GLASSES
dP
~
u
~
8
8
H
:E:
U)
~8
400
Figure 7.
Effect of increasing Ag 2o on the infrared-transmittance of
xAg 2o. (100-x)B 2o3 devitrified glasses.
m
\.0
WAVE LENGTH,
2.5
3.0
5.0
6.0
8.0
MICRONS
9.0
15.0
10.0
20.0 25.0
DEVITRIFIED GLASSES
dP
ji:l
u
X
~
8
8
H
~
(f)
~8
4000
Figure 8.
3500
3000
1500
FREQUENCY, CM-l
400
Effect of increasing Ag 2o on the infrared-transmittance of
xAg 2o. (100-x)B 2o3 devitrified glasses.
-..J
0
WAVE LENGTH
2.5
3.0
5.0
6.0
8.0
1
MICRONS
9.0
10.0
15.0
20.0
25.0
H Bo
3 3
(CRYSTAL)
dP
rLl
u
~
E-4
E-4
H
::8
U)
~
8
000
3500
3000
500 400
FREQUENCY I CM-l
Figure 9.
Infrared-transmittance curves of Ag o and H Bo
2
3
3
crystals.
-...]
I-'
72
REFERENCES FOR APPENDIX C
(1)
V.U. Schiedt and H. Reinwein, "Zur Infrarot-Spektros-
kopie von Aminosauren," Z. Naturf.,
(2)
7
H.M. Stimson and M.J. O'Donnell,
[B]
270-277
(1952).
"The Infrared and
Ultraviolet Absorption Spectra of Cytosine and Isocytosine
in the Solid State," J. Amer. Chern. Soc., 74
[7]
1805-1808
(1952).
(3)
N.F. Borrelli, B.D. McSwain and G. Jen Su,
"The Infrared
Spectra of Vitreous Boron Oxide and Sodium Borate Glasses,"
J. Phys.
(4)
Chern. Glasses, 4 [1]
J. Krogh-Moe,
11-21 (1963).
"Interpretation of the Infrared Spectra
of Boron and Alkali Borate Glasses," J. Phys. Chern. Glasses,
6
[2]
( 5)
46-54
(1965).
J. Krogh·-Moe,
"The Structure of Vitreous and Liquid
Boron Oxide," J. Non. Cryst. Sol., 1
(6)
R.L. Mozzi and B.E. Warren,
s.
269-284
(1969).
"The Structure of Vitreous
Boron Oxide," J. Appl. Cryst., 3 [4]
(7)
[4]
251 (1970).
Anderson, R.L. Bohon and D.D. Kimpton,
"Infrared
Spectra and Atomic Arrangement in Fused Boron Oxide and
Soda Borate Glasses,
"J. Amer. Ceram. Soc.,
38
[10]
370-377
(1955).
(8)
P.E. Jellyman and J.P. Proctor,
"Infrared Reflection
Spectra of Glasses," J. Soc. Glass Tech., 39 pp. 173-192T
(1955).
(9)
H. Moore and
w.
McMillan,
"Study of Glasses Consisting
of the Oxides of Elements of Low Atomic Weight:
Glass Tech., 40 pp. 97-138T
(1956).
II, "J. Soc.
73
( 10)
R.V. Adams and R.W. Douglas,
"The Absorption of
Infrared Radiation and the Structure of Glasses," Glastech.
Ber. V, International Glass Congress, Heft VII pp. 12-24
(11)
J. Krogh-Moe,
"Structural Interpretation of Melting
Point Depression in the Sodium Borate System,
Chern. Glasses,
( 12)
\'J.
H.
3
[1]
(1959).
"J. Phys.
1-6 (1962).
Zachariasen and H. A. P let tinger,
"Refinement of
the Structure of Potassium Pentaborate Tetrahydrate,"
Acta Cryst., 16 pp.
(13)
J. Krogh-Moe,
376-379
(1963).
"The Crystal Structure of Lithium DiActa Cryst., 15 pp. 190-193
(14)
J. Krogh-Moe,
cs20. 3B203,
(15)
J. Krogh-Moe,
borate,"
(16)
"The Crystal Structure of Cesium Triborate,
Acta Cryst., 13 pp.
II
889-892
(1960).
"The Crystal Structure of Silver Tetra-
Acta Cryst., 18 pp.
77
(1965).
P.J. Bray and J.G. O'Keefe, "NMR Investigations of
Alkali Borate Glasses," J. Phys. Chern. Glasses, 4[2]
(17)
(1962).
A.M. Bishay and
s.
Arafa,
37
(1963).
"Gamma-Induced Absorption
and Structural Studies of Arsenic Borate Glasses," J. Amer.
Ceram. Soc., 49
[8]
423-430
(1960).
74
APPENDIX D
Density Measurements
1.
Theory
The density of the sample at t°C is given by:
=
w1
(dt - d ) + d
1
g
{1)
g
where
wl g is the weight of the sample in air,
w2 g is the weight of sample + suspension in air,
w3 g is the weight of the sample + suspension in xylene,
dt g/cc is the density of xylene at t°C,
1
g/cc is the density of air at room temperature.
g
w3 is actually made up of:
d
1.
weight of sample alone in xylene,
2.
weight of unimmersed suspension in air,
3.
weight of immersed suspension in xylene; this is
equal to the weight of the immersed suspension in
air minus the weight loss of the immersed suspensian in xylene,
4.
force due to surface tension.
The weight loss due to the immersed suspension in xylene
given in item 3 is equal to:
wt. of suspension in air
X density of xylene
density of suspension material
w
3
=
(wt. of sample in xylene)
+ (wt. of unimmersed suspension in air)
+ (wt. of immersed suspension in air)
75
(wt. of immersed suspension in air
density of suspension material
X density of
xylene)
+ force due to surface tension
i.e
= (wt. of sample in xylene)
w3
+ (wt. of whole suspension wire in air)
~l
where
~
·~
2
-
~
-
~2
=
wt. of immersed suspension in air
density of suspension material
1
= force due to surface tension
' can be determined as follows
1
(2)
where w
4
is the weight of the sample + immersed part of
suspension,dT is the density of the suspension material
(tangsten)
=
19.3 g/cc
Using the result given in reference (1), the density
of xylene at 25.6°C was found to be equal to 0.860 g/cc.
Also
~
2
was calculated in the same manner as given in this
reference and was found to equal 0.00063 g .
. equation (1)
can be written as:
(dt - d ) + d
1
g
g
Procedure:
The weight w
of each glass sample in air was first
1
determined, followed by the weight w 2 of the samples when
suspended by a tungsten wire.
The glasses were free of bubbles
76
as seen by the naked eye and an optical microscope.
Their
surface was clean and they were kept in xylene for some time
before measurements because of their hygroscopic nature.
Next a beaker with the xylene, containing the sample, was
put into a desiccator and de-aerated for a few minutes.
The
beaker was then transferred to the bridge of the balance
and allowed to attain the balance temperature.
The sample
was next suspended from the hook of the balance pan and the
weight of the sample in xylene w
3
noted.
This procedure was
repeated several times and the average weight noted for the
same temperature.
Between each weighing operation, enough
time was allowed for the xylene vapor to attain equilibrium
with the enclosed air.
To heat the xylene to the wanted temperature, 25.6°C,
a stirring rod was warmed on a hot plate and the xylene stirred
with it.
Precautions were taken to allow the suspended sample
to reach temperature equilibrium with the xylene.
After the weighings, the suspension wire was cut just
above the liquid line, then the sample and attached piece
of wire were dried and weighed in air w 4 .
77
REFERENCES FOR APPENDIX D
(1)
P.M. Vera,
"Imperfections in the Ag-In System and
Lattice Parameters of Cadmium Oxide," M.S. Thesis, U.M.R.
(l970).
78
APPENDIX E
This appendix was submitted for publication in the
Journal of the American Ceramic Society.
Mixed Cation Effect in Silver Borate Glasses
79
The internal friction peaks in simple alkali and mixed
alkali silicate glasses have been studied intensively in
.
th e pas t f ew years ( 1 , 2 , 6 , 7 , 8) .
Llterature reports about
the internal friction of mixed alkali borate glasses are
scarce.
However, electrical conductivity measurements show
that mixed alkali borate glasses behave in the same fashion
as mixed alkali silicate glasses:
there is a sharp drop in
the conductivity with a minimum in the conductivity isotherms
when one alkali is replaced by another( 3 ).
In the course of our study of the structure and properties
of binary silver borate glasses( 4 ) internal friction studies
were conducted to determine the effect of small substitutions of sodium in silver, and silver in sodium glasses.
Also a glass 0.95 Ag o·0.05 cu 0·4 B o
was examined.
2
2
2 3
Silver
is generally considered to behave as a modifier similar
to alkali in the glass structure.
The apparatus and the
method used were the same as those used by Day et. al
( 1)
.
Internal friction curves for the binary silver borate
glass Ag 0·4 B o
and the corresponding glass with a small
2
2 3
sodium substitution for silver 0.95 Ag o·0.05 Na o·4 B 2 o
2
2
3
are shown as solid and dashed dotted lines respectively in
fig.
1.
Internal friction curves for the binary sodium
borate glass Na 0·4 B 2 o 3 and the corresponding glass with
2
a small silver substitution for sodium are similarly
illustrated in fig.
2.
In both cases the low temperature
"alkali peak" has decreased and shifted to a higher temperature
in the mixed glasses. And in both cases a second peak at a
80
higher temperature is observed in the mixed sodium-silver
glasses.
The dashed curves in figures 1 and 2 show the
development of this high temperature peak for the glass
0.5 Ag 2 0·0.5 Na 2 0·4 B o
with its equal shares in Na and
2 3
Ag.
Similar large high temperature peaks
peaks")
("mixed alkali
have been observed in mixed alkali silicate glasses
and attributed by Day and coworkers(l)
involving both alkalis.
to a new relaxation
The same explanation is offered for
the mixed alkali silver borate glasses.
The high tempera-
ture peak observed in one-alkali silicate glasses, frequently
called the "non-bridging oxygen" peak, and somewhat overlapping with the mixed alkali peak in some silicate compositions,
is not present in the borate compositions reported
here.
A second high temperature peak in binary silver borate
glasses is only observed when more than 33% Ag o are present( 4 )
2
Fig.
3 shows the internal friction curve for a glass
0.95 Ag o-0.05 cu 0·4 B o
in comparison with that of the
2 3
2
2
Again, the low temperature
binary silver borate glass.
"alkali peak" has decreased and shifted toward higher temperature and a pronounced high temperature "mixed alkali peak"
Sim-
has appeared in the mixed copper silver borate glass.
ilar observations have been made in silicate glasses containing copper and alkal1. by Wey 1 et.
al. (S)
and Wh1"te(lO).
In conclusion, mixed silver sodium (and copper)
borate
glasses exhibit internal friction like mixed alkali silicate
glasses.
Silver and copper participate in relaxation processes
81
just like second alkalis.
82
. ........
.... ,,
''
,
\
'
,, ,'
'' '
''
-
---- -........ -
...
' ........,
.... , ....
........ ......
C\J
m
~
.
C\J
0
l()
C\J
CD
~
0
0.
0
0
C\J
C)
<{
C\J
C)
l()
~
0
<{
J"()
0
C\J
m
~
0
z
0
...._ ............
-....
..........
" '\
1
....... ........
....... ....... .... _
.......
--......\ ........
0
J"()
J"()
I
J"()
0
0
0
'
'
.......
.... ....
....
,)
t-
..
' ',,
''
w
'
0:::
o:::>
\
\
w~--:
\
'
C\J
<(
0:::
\
0
z
\
'
I
I
l()
I
I
I
d
I
w
a...
~
w
t-
0
C\J
C)
<{
.
L()
0
I•
I•
I
INTERNAL FRICTION, QFigure 1.
1
x 10
Internal friction curves for
glasses; frequency 0. 5 Hz.
3
(l-x)Ag 2 o.xNa 2 0.4B 2 o 3
83
0
0
1"0
I
I
1"0
0
C\J
m
v
<{
lO
C\J
co
¢
.
0
0
0
0
C\J
z
0
C\l
0
z
CD
......
....... ..
C\J
Ol
1"0
C\J
¢
0
0
1"0
0
lO
m.
0
...
..
w
'
a::
\
\
0
::::>
\
~
\
\
C\J
0'
<{
''
0::
w
\
.
\
.
a_
\
I{)
\
0
1
I
0
I
I
I
I
'
C\J
0
z
::?i
t--
w
•
\:
' I
.
I{)
0
I
I
I•
-
I
INTERNAL FRICTION,
Figure 2.
Internal friction curves for
glasses; frequency 0.5 Hz.
(l-x)Na 0.xAg 0.4B o
2
2
2 3
84
'
... ...... ...
....... .......
......... .....
... .....
''
'
\
\
I
I
/
/
, ""
_,.;
./
J'()
0
(\J
CD
~
.
0
.
(\J
::J
u
tO
rt')
0
C\J
CD
q-
0
0.
0
.
lJ.J
a::
' ' ......
::>
1--
' ' ',
(\J
0'
<2:
0
(\J
0'
<(
LO
.
(]')
0
<(
'
a::
' ''
lJ.J
Cl..
'' \
~
'
lJ.J
1--
\
\
\
\
\
''
'''
'
I
I
I
I
0
-
------~------._------------~------~----~------------~----__.00
I()
co
I
INTERNAL FRICTION, Q- 1 x 10 3
Figure 3.
Internal friction curves for
glasses; frequency 0.5 Hz.
(l-x)Ag 2 o.xcu 0.4B o
2
2 3
85
REFERENCES FOR APPENDIX E
(1)
J.E. Shelby, Jr., and D.E. Day,
"Mechanical Relaxa-
tions in Mixed-Alkali Silicate Glasses: I."
52
soc • '
(2)
J. Arner. Ceram.
[ 4 J 16 9 -7 4 ( 19 6 9) .
Emil Deeg,
"Relationship Between Structure and Meehan-
ical-Acoustical Properties of Single Glasses: N."
Ber. 31
(3)
[6]
229-40
Glastech.
(1958).
K.A. Kostayan,
"Investigation of the Conductivity
Neutralization Effect in Fused Borate Glasses."
Structure
of Glass, Vol. 2, pp. 234-236, Consultants Bureau, New York
(1960).
(4)
E.N. Boulos and N.J. Kreidl, "Structure and Properties
of Silver Borate Glasses," to be published.
(5)
L. c. Hoffman and W.A. Weyl,
"A Survey of the Effect
of Composition on the Internal Friction of Glass,"
Indus try 3 8 [ 2 ] 81 - 8 5 ,
(6)
Glass
1 0 4 ( 19 5 7 ) .
R.J. Ryder and G.E. Rindone, "Internal Friction of Single
Alkali Silicate Glasses Containing Alkaline-Earth Oxides: II."
(7)
H.K. Sheybany,
Glasses."
(8)
'"l'he Structure of Mixed-Alkali Silicate
Verres et Refract.
W.A. Weyl, and E.c. Marboe,
Vol. II, pp. 470-507,
(9)
2 pp. 127-299
(1948).
"The Constitution of Glasses."
Interscience (1964).
G.L. McVay and D.E. Day,
"Diffusion and Internal Fric-
tion in Na-Rb Silicate Glasses," J. Am. Cer. Soc.
(1970).
( 10)
P.L. White,
Glasses."
53
.
[9]
508-513
"Mechanical Relaxations in Copper Aluminosilicate
To be published in J. Amer. Cer. Soc.
86
APPENDIX F
Internal Friction
The internal friction peak heights and temperatures for
the silver borate glasses studied and shown in fig.
section III 6 are given in table I.
(17)
87
LOW TEMP. PEAK
'Alkali Peak'
Glass
Temp.
oc
Height
o- 1 xlo3
HIGH TEMP. PEAK
'Nonbridg. Oxygen Peak'
Temp.
oc
Height
o-lxlo3
x=lO
199
0.30
--
--
x=l5
105
2.25
--
--
x=20
16
3.70
--
--
x=28
-
78
5.45
80
0.20
x=34
-100
4.90
85
1.00
TABLE I.
Temperature and height above back-ground for
the low and high temperatures peaks, in the
88
VII.
VITA
Edward Nashed Boulos was born on May 19, 1941, in
Cairo, Egypt.
He received his primary and secondary
education in Damanhour, Egypt, and a Bachelor of Science
degree in Chemistry and Physics from Cairo University in
May 1963.
Following graduation from University, he worked as
advisor of glass technology, Industrial Control Department,
Ministry of Industry, Cairo, Egypt; at the same time, he
was enrolled as part-time graduate student in the American
University, Cairo, from which he received his M.S. degree
in Solid State Science on June 1966.
From November 1967 until the present, he attended
graduate school at the University of Missouri-Rolla studying
for a Ph.D. degree in Ceramic Engineering.
August 1967, he was married to the former Mervet Saleh,
Egypt.
They now have one daughter Nermine.