Luminescence of Divalent Europium in the BaO-MgO-P2OsSystem
Costas C. Lagos*
Phosphor Research Laboratory, Sylvania Lighting Center, Danvers, Massachusetts
ABSTRACT
The binary and t e r n a r y compounds in the BaO-MgO-P205 system w e r e
activated with divalent e u r o p i u m and e x a m i n e d for luminescence u n d e r
2537 and 3650A excitation. T h r ee compounds, Ba3(PO4)2, t h e l o w - t e m p e r a ture f o r m of Ba3P4013, and BaMgP207 produced bright phosphors w i t h blue
emission. Many other compounds in the t e r n a r y system also fluoresced blue,
but w i t h reduced intensities.
Very little w o r k has been previously r e p o r t e d on
the luminescence of phosphates activated w i t h divalent europium. In 1967, W a n m a k e r and t e r V r u g t
(1) r e p o r t e d on the uv and cathodo excitation of the
divalent e u r o p i u m activated pyrophosphates of Ca, Sr,
Ba, Zn, Cd, and Mg; G o r b a c h e v a (2) in 1966 presented
information on the u v excitation of the divalent
europium activated orthophosphates of s tr o n t iu m and
magnesium; and N a z a r o v a (3) in 1961 published on
the u v and cathodo excitation of the pyro-, meta-, and
orthophosphates of strontium. To our k n o w l e d g e no
w o r k has been reported on the divalent europium
activation of compounds in either the BaO-P205 or
BaO-MgO-P205 systems. Hoffman (4) in 1963 reported
the use of e u r o p i u m as an a c ti v a to r in the B a O - M g O P.,O5 system, but the e u r o p i u m was probably t r i v a l e n t
because only red emission was mentioned.
The p r i m a r y interest of the present study was the
d e v e l o p m e n t of phosphors for application in fluorescent or HPMV lamps. Compounds which did not show
any emission under 2537 or 3650A excitation w e r e not
investigated further.
Some of the better phosphors in the BaO-MgO-P20.~
system w e r e bright enough for fluorescent lamp applications. These phosphors were: Ba3(PO4)2:Eu +2,
the l o w - t e m p e r a t u r e form of Ba3P4013:Eu +2, BaMg._,
(PO4) 2: Eu +2, Ba2MgP4013: Eu +2, and BaMgP2OT: Eu +2.
All o t h e r compounds produced either no luminescence
at all or v e r y w e a k divalent or t r i v a l e n t e u r o p i u m
emissions.
Experimental
The chemicals used in the preparation of the phosphors w e r e luminescent grade BaHPO4 and BaCO3,
reagent grade (NH4)2HPO4 and 3MGCO~.Mg(OH)2.
3H20, and 99.9% pure Eu203. Phosphor blends w e r e
prepared by d ry m i x i n g of the r a w materials; no w et
precipitations w e r e made. F o r m u l a t i o n s w e r e m a d e up
to stoichiometry and no deliberate excess of anion was
used in any of t h e preparations. T h e ratio of a c t i v a t o r t o - m a t r i x cation in moles was 0.02 to 1, i.e., for e v e r y
mole of total cation 0.02 moles of Eu w e r e added as
Eu20~.
Firing of all blend m i x t u r e s was made in two steps:
(i) a l o w - t e m p e r a t u r e prefiring usually for 3 hr at
700~ in a stagnant air a t m o s p h e r e to p r e v e n t spewing and subsequent loss of m a t e r i a l and also to allow
the 3MgCO3.Mg(OH)2.3H20 and (NH4)2HPO4 which
h a v e low decomposition t e m p e r a t u r e s to react m o r e
readily with the other r a w materials; (ii) a final
higher t e m p e r a t u r e firing in a 1% H2-99% N2 reducing
gas m i x t u r e flowing o v e r the samples with the firing
t e m p e r a t u r e d ep e n d in g on the compound that is being
prepared. B e t w e e n firings all samples w e r e r e m i x e d
by a thorough grinding with a m o r t a r and pestle.
Spectral energy distribution curves w e r e run on the
luminescent phosphor samples using an emission spectral r a d i o m e t e r designed by Eby (5). The emission
* Electrochemical Society Active Member.
K e y w o r d s : l u m i n e s c e n c e , p h o s p h o r s , 2537 e x c i t a t i o n , 3650 e x c i t a t i o n , Eu+'-' activation, barium phosphates, m a g n e s i u m phosphates,
b a r i u m m a g n e s i u m phosphates, s p e c t r a l e n e r g y d i s t r i b u t i o n .
band peak height intensities of the phosphor samples
w e r e compared to the emission band peak height intensity of the high brightness Zn2SiO4:Mn phosphor,
which peaks at 527 n m and is used as a control for
our radiometer. All phosphor emission intensities in
this p ap er are expressed as peak height percentages
of the peak height of the Zn2SiO~:Mn r a d i o m e t e r
standard phosphor. This comparison is not an absol u t e l y correct comparison in some cases because of
w a v e l e n g t h - e n e r g y differences b e t w e e n the phosphor
samples and the Zn2SiO~:Mn standard, but for the
m a j o r i t y of the phosphors being discussed here this
m e t h o d is a great i m p r o v e m e n t over the use of a
plaque tester w h e r e differences b e t w e e n n a r r o w and
wide emission band widths play a misleading role in
brightness comparisons and evaluations. H a l f - h e i g h t
widths and peak height intensities of t h e emission
bands of some w e l l - k n o w n phosphors w e r e m e a s u r e d
on our r a d i o m e t e r and w e r e also included here as
references for the phosphors reported in this paper.
Finally, x - r a y diffraction patterns w e r e obtained
on all fired samples using copper Ks-radiation. The
x - r a y diffraction angle scan was varied f r o m a 20 of
2 ~ to a 2e of 60 ~ w h i ch was quite sufficient for proper
identification of the compounds and polymorphs.
Results and Summary
T h e r e w e r e a total of f o u r t e e n compounds and polymorphs in the BaO-MgO-P205 t e r n a r y system which
w e r e p r e p a r e d with divalent e u r o p i u m as the activator. In order to simplify t h ei r presentation the compounds h a v e been separated into four categories: (i)
metaphosphates and g a m m a compound, (ii) t e t r a phosphates, (iii) pyrophosphates, and (iv) orthophosphates.
Metaphosphates and gamma compound.--Two m e t a phosphate compounds Mg(PO3)2 (6) and Ba(PO3)2
(7) and the -y compound which had the composition 6.3
BaO-1.0 MGO-2.7 P205 (4) w e r e tested w i t h d i v a l e n t
e u r o p i u m as the activator. Of these t h r e e compounds
only the b a r i u m m e t a p h o s p h a t e showed any fluorescence which could be a t t r i b u t e d to divalent europium.
F i g u r e 1 shows t h e emission cu r v e for this phosphor
under 2537A excitation. The emission band of the
phosphor peaked at 375 n m with a h a l f - h e i g h t w i d t h
of 31 nm and a peak height intensity only 5% of the
peak height of the r a d i o m e t e r standard, Zn2SiO4:Mn.
The u v emission of the B a ( P O 3 ) 2 : E u +2 phosphor was
quite low w h e n c o m p a r e d to the r ef er en ce phosphor
BaSi20~:Pb w h i ch peaked at 355 nm with a ha l f height w i d t h of 41 n m and was 205% of the Zn2SiO~:
Mn standard. W h e n visually observed u n d er 2537A
excitation, the B a ( P O 3 ) 2 : E u +2 phosphor had a w e a k
violet emission.
The other t w o compounds Mg(PO~)2 and the ~, compound (6.3 BaO-1.0 MGO-2.7 P205) w e r e not activated
by divalent europium. U n d e r 2537A excitation the
only emission that was observed was a w e a k r e d
emission which, w h e n e x a m i n e d w i t h t h e spectral
radiometer, was found to be the typical line emissions
of t r i v a l e n t europium.
1271
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1272
J. Electrochem. Soc.: S O L I D S T A T E
2 Eu+2
mr"
ILl
;m
hl
I.I.I
t.....1
r
/
300
J
I
5"50
400
I
450
5 O0
WAVELENGTH IN NANOMETERS
Fig. 1. Spectral energy distribution of the emission of Ba(PO3).2:
band at 438 nm combined to give a single wide c u r v e
with a long tail. X - r a y diffraction data of this phosphor corresponded to the data of Harrison (8) for the
l o w - t e m p e r a t u r e f o r m of Ba~P4013, and t h e r e w e r e
no other extraneous phases present 9
This double emission band c u r v e might h a v e been
the result of divalent e u r o p i u m emission f r o m two
different cationic sites in the compound, but since no
crystallographic st r u ct u r e determinations had been
m a d e on t h e compound, no definite conclusions could
be drawn.
The wide emission c u r v e of t h e low t e m p e r a t u r e
Ba3P4OI3:Eu +2 m a t e r i a l resulted in a phosphor w hi c h
had a m o d e r a t e l y bright b l u e - w h i t e emission w h e n
visually observed u n d er 2537A excitation 9 P l a q u e test
brightness m e a s u r e m e n t s w e r e m a d e on this phosphor
and compared to similar m e a s u r e m e n t s made on the
w e l l - k n o w n CasF( PO 4 ) 3 : Sb phosphor which had a
wide emission band at 494 n m w i t h a h a l f - h e i g h t width
of 116 nm.
Plaque
Eu +2. 2537.~ e x c i t a t i o n
Tetraphosphates.--There
are th r e e t e t r a p h o s p h a t e
compounds that exist in the BaO-MgO-P20~ t e r n a r y
system. These are the Ba2MgP4Ot3 (4) compound and
the high- and l o w - t e m p e r a t u r e polymorphic forms of
Ba3P4013 (8) whose transition t e m p e r a t u r e is at
870~
9Activation of the h ig h - and l o w - t e m p e r a t u r e forms
of Ba3P4018 with divalent e u r o p i u m resulted in two
interesting emission curves (Fig. 2). The h i g h - t e m p e r a t u r e form of Ba3P4013:Eu +2 gave a v e r y wide
emission band of 197 n m h a l f - h e i g h t w id th w i t h the
band peak located at 575 nm. Because of this u n u su al l y
w i d e emission c u r v e the phosphor emitted a fairly
bright yellow when observed under 2537A excitation,
but its emission band peak height intensity was only
7.4% of the Zn.~SiO4:Mn r a d i o m e t e r standard and 38%
of the reference phosphor CaSiO3:Pb, Mn which
peaked at 618 n m with a h a l f - h e i g h t w id th of 87 nm.
The position of this wide emission band was also u n usual in that it was located f u r t h e r towards the longer
w a v e l e n g t h s than w e r e the emission bands of practically all of the other divalent e u r o p i u m phosphors
which were found in the BaO-MgO-P205 system 9 Most
of these other emission bands w e r e located in the 400450 n m region of the spectrum.
The l o w - t e m p e r a t u r e form of Ba3P40~3 also gave a
v e r y unusual emission c u r v e with divalent e u r o p i u m
(Fig. 2). Its emission band was located at 438 nm, and
its intensity was 18% of the peak height intensity of
the Zn2SiO4:Mn standard. The h a l f - h e i g h t width
m e a s u r e m e n t was not too m e a n i n g f u l in this case because of the e x t r e m e a s y m m e t r y of the emission curve
towards the long w a v e l e n g t h end of the spectrum.
This a s y m m e t r y appeared to be caused by the presence of another less intense emission band in the
vicinity of 500-510 nm, and this band plus t h e m a i n
f'~'\ \
m ~
9
t
/ /- -\\
/ \
400
\
"
"\\
,
350
D e c e m b e r 1968
SCIENCE
s;o
s;o
700
WAVELENGTH IN NANOMETERS
Fig. 2. Spectral energy distribution of the emission of:
Ba2MgP4Oz3:Eu + 2 curve A; Ba3P4Ot3:Eu +2, high-temperature
form, curve B; Ba3P4013:Eu+2; low-temperature form, curve C;
2537~ excitation
CasFq P O o ~ : S b
B a a P 4 O I 3 : E u *'-'
Red
Green
Blue
100~}
105%
100e~
111r
100e;
125f~
These data showed the divalent e u r o p i u m activated
m a t e r i a l to be slightly b r i g h t e r and more blue t h a n
the C a s F ( P O 4 ) a : S b phosphor which is used in fluorescent lamps for color correcting purposes 9 Use of the
low t e m p e r a t u r e BaaP4Ota:Eu +2 phosphor in place of
CasF(PO4)~:Sb in fluorescent lamp phosphor blends
would subsequently yield more efficient fluorescent
lamps 9
D i v a l e n t e u r o p i u m activation of Ba2MgP4OI.~ r e sulted in a phosphor w i t h an emission band at 403 n m
and a h a l f - h e i g h t w i d t h of 28 n m with a peak height
intensity of 59% of the Zn~SiO4: Mn standard (Fig. 2).
This phosphor fluoresced a m o d e r a t e l y bright deep
violet w h e n v i e w e d u n d e r 2537A excitation, and it
was one of the b r i g h t e r divalent e u r o p i u m activated
phosphors in the BaO-MgO-P20.~ system 9
The emission properties of the b a r i u m magnesium
tetraphosphate phosphor w e r e radically different
from those of either of the b a r i u m tetraphosphates.
The emission band intensity of the m a g n e s i u m containing phosphor was greatly increased by a factor of
m o r e than three o v e r the l o w - t e m p e r a t u r e b a r i u m
tetraphosphate phosphor and by a factor of more than
six over the h i g h - t e m p e r a t u r e b a r i u m tetraphosphate
phosphor, while the band w i d t h of the m a g n e s i u m
containing m a t e r i a l was decreased considerably by
factors of one-fifth and o n e - s e v e n t h of the l o w - and
h i g h - t e m p e r a t u r e forms of b a r i u m tetraphosphate, r e spectively. Apparently, the r ep l acem en t in the
Ba3P40~3 compounds of even only one of the t hr e e of
the larger ionic radius b a r i u m cations by the smaller
m a g n e s i u m cation to f o r m the b a r i u m - m a g n e s i u m
compound changed the structures of the high and low
b a r i u m t et r ap h o sp h at es quite drastically so that t h e r e
was no similarity at all b e t w e e n the m a g n e s i u m containing and either of the n o n m a g n e s i u m containing
crystal structures and t h ei r subsequent emission properties.
Pyrophosphates.--Four pyrophosphates exist in the
BaO-MgO-P205 t e r n a r y system. These compounds are
Mg2P2Or (6), BaMgP207 (4), and Ba2P207 (9), which
exist in two polymorphic forms, a which is t he low
t e m p e r a t u r e form, and 5 which is the h i g h - t e m p e r a t u r e
form. The a to 5 transition t e m p e r a t u r e is at 790~
H e r e again, as it was p r e v i o u s l y in t h e case of t he
m a g n e s i u m m e t a p h o s p h a t e compound and t h e ~ compound, it was not possible to reduce the t r i v a l e n t e ur op i u m to divalent e u r o p i u m in the Mg2P207 compound 9
With 2537A excitation the only fluorescence that was
observed in the e u r o p i u m activated Mg2P207 m a t e r i a l
was an e x t r e m e l y w e a k red fluorescence which on e xamination by the spectral r a d i o m e t e r was found to be
the typical line emissions of plus t h r ee europium.
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Vol. 115, No. 12
LUMINESCENCE
OF DIVALENT
EUROPIUM
1273
Bo31P04) 2
Eu+2
550
400
s~d
~o
TOO
350
400
500
600
700
==
oc
400
300
WAVE~_FN~THIN NANOUrTEeS
Fig. 3. Spectral energy distribution of the emission of:
BaMg P207 :Eu + 2, curve A; Ba2P207:Eu +~, curve B; 2537,~,
excitation
uJ
~
350 '
The b-Ba2P207 compound was completely dead to
253.7/excitation while the a-Ba2P207 compound had a
fair w h i t e - b l u e emission, a-Ba2P207 had a n emission
b a n d which peaked at 406 n m with a peak height i n tensity 11.4% of the Zn2SiO4:Mn standard and a halfheight width of 32 rim. Figure 3 shows the emission
curve for this phosphor.
BaMgP,.,O7:Eu +2 whose emission curve is also given
in Fig. 3 was one of the brightest phosphors in the
BaO-MgO-P205 system. The phosphor appeared a brilliant deep violet w h e n viewed u n d e r 2537A excitation,
and it had an emission peak at 402 n m with a halfheight width of 45 n m and a peak height intensity
1(}3% of the Zn2SiO4:Mn standard. W h e n compared to
the reference phosphor CaWO4 which peaked at 422
n m with a half-height width of 116 nm, the BaMgP2OT:
Eu +' phosphor was approximately three times as i n tense.
Orthophosphates.~There are four orthophosphate
compounds in the BaO-MgO-P205 t e r n a r y system:
Ba3(PO4)2 (10), Ba2Mg(PO4)2 (4), BaMg~(PO4)2 (4),
and Mg3(PO4)2 (6).
Table I lists the emission properties of the divalent
europium activation of these compounds and Fig. 4
gives the spectral energy distribution curves. Two reference phosphors, CaWO4 and CaSiO~:Pb, M n were
also included in the table for comparison purposes,
CaWO4 for the e x p e r i m e n t a l phosphors in the blue
region of the spectrum and the CaSiO3:Pb, Mn for the
Ba.~Mg(PO4)2 phosphor which peaked at 585 nm.
The Ba3(PO4)2:Eu +2 phosphor was the brightest
phosphor found in the BaO-MgO-P205 system. It was
138.5% of the Zn2SiO4:Mn radiometer s t a n d a r d a n d
over four times as intense as the CaWO4 reference
phosphor.
Divalent e u r o p i u m activation of the Ba2Mg(PO4)2
compound resulted i n a wide band emission phosphor
whose spectral energy distribution curve was similar
in width to the l o w - t e m p e r a t u r e Ba3P~OI~:Eu +2 phosphor and similar in width and emission to the hight e m p e r a t u r e Ba3P4OI3:Eu § phosphor. The emission
band peak height of Ba2Mg(PO~)2:Eu +2 was only
about half as intense as the CaSiO~:Pb, Mn reference
phosphor, but because of the extreme width of its
emission band, the Ba2Mg (PO~) 2: Eu + 2 phosphor apTable I. Emission properties
Peak
Phosphor
Position,
nrn
Baa(POD.-,:Eu ~'-"
Ba.,AVIgIPOD=:Eu§
BaMg~(POD 2:Eu §
Mga(PO, I ~:Eu*~
CaSi(~:Pb, Mn
CaWO~
415
585
418
425
618
422
V2 Ht.
% of
w i d t h , Zn.~SiO4:Mn,
nm
%
31
148
77
47
87
116
138.5
8.5
24.5
13.0
19.3
31.5
Emission color
u n d e r 2537
Exe.
Mod.
Mad.
Mad.
Mad.
deep violet
I t yel,
blue
blue
red orange
Mod. blue
:
d
oc
~o
0 4 ) 2 : Eu + 2
4()0
500
~ M ( : ]
'
4o
660
700
3(P04)29Eu+2
5oo~
l
~o
WAVELENGTH IN NANOMETERS
x)O
Fig. 4. Spectra| energy distribution of the emission of
Ba3(PO4)2:Eu +2, Bo2Mg(PO4)2:Eu +2, BaMg.,(PO4)2:Eu +2, and
Mg3(PO~)2:Eu +2; 2537,~ excitation.
peared a moderately bright yellow w h e n visually observed u n d e r 2537A excitation.
A phosphor with a half-height width of 77 n m and
an emission peak at 418 n m was obtained with
BaMg2(PO4)2:Eu +2. This phosphor was about threefourths as intense as the CaWO4 reference phosphor
and its emission b a n d width half-height of 77 n m
was wider t h a n usual for a divalent e u r o p i u m activated
phosphor with an emission in the near u v - b l u e region
of the spectrum. All of the other phosphors in the
BaO-MgO-P205 system which peaked in this same region of the spectrum had considerably smaller emission
band half-height widths v a r y i n g from 31 to 47 nm.
The final m e m b e r of the orthophosphate phosphor
group was Mg3(PO4)2:Eu +2. Its intensity was less
than half of the CaWO4 reference phosphor, and its
emission band peak was located at 425 n m with a halfheight width of 47 nm. Magnesium orthophosphate was
the only pure m a g n e s i u m containing compound which
gave an emission with divalent e u r o p i u m activation.
The other two m a g n e s i u m compounds Mg(PO3) and
Mg2P207 which were discussed previously could not be
activated with divalent e u r o p i u m but instead gave
weak red emissions which were found to be trivalent
e u r o p i u m line emissions.
All of the divalent e u r o p i u m activated phosphors in
the BaO-MgO-P205 system which fluoresced u n d e r
2537A excitation were also found to fluoresce quite
strongly u n d e r 3650A excitation. Emission characteristics, such as band location and band width were found
to be the same u n d e r 3650A excitation as they were
u n d e r 2537A excitation.
The yellow luminescence of the Ba2Mg (PO4) 2: Eu + '~
phosphor u n d e r 3650A excitation was found to be reduced greatly w h e n the phosphor was heated to 300~
r u l i n g out its applicability in high pressure m e r c u r y
lamps. No other t e m p e r a t u r e - d e p e n d e n c e studies were
attempted.
Introduction of the divalent europium activated
phosphors into fluorescent lamps posed no particular
problems in lamp processing or lamp life. N o r m a l lamp
processing conditions were not severe enough to reoxidize the europium from a valence of plus two to
plus three and s u b s e q u e n t l y change the emission color
and decrease the brightness of the phosphor. Table II
compares the 40-w fluorescent lamp l u m e n - l i f e data
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J. Electrochem. Soc.: S O L I D S T A T E
1274
Table II. Comparison of data
100 H o u r s
Phosphor
0 Hours
lms
Lumens
% of
0 Hours
Table III. Summary of emission data
300 H o u r s
Lumens
Peak
% of
0 Hours
Phosphor
B a ~ ( P O D e : E u +c
Cool W h i t e Ca
Halophosphate
D e c e m b e r 1968
SCIENCE
310
300
96.8
294
94.8
3299
3234
98.0
3148
95.4
obtained for t he intense n a r r o w emission band
Ba3 (PO4)2: Eu +2 phosphor to similar data obtained for
a typical c o o l - w h i t e halophosphate phosphor.
Because of the disparity in emission band widths
b e t w e e n the phosphors, the total lu m e n output of the
B a 3 ( P O O 2 : E u +2 phosphor was u n d e r s t a n d a b l y l o w er
than that of the halophosphate phosphor, but the per
cent of zero hour results w e r e v i r t u a l l y the same for
both phosphors at 100 hr and again at 300 hr.
A detailed e x a m i n a t i o n and comparison of the emission bands of the various d i v a l e n t e u r o p i u m activated
phosphors which w e r e found in t h e BaO-MgO-P205
system indicated that the intensities and widths of the
divalent e u r o p i u m emission bands of practically all of
t he phosphors in the system appeared to be a function
of the emission band location in the visible spectrum.
When the divalent e u r o p i u m emission band was located at the shorter w a v e l e n g t h end of the spectrum,
the emission band was quite n a r r o w and intense. On
the other hand, when the emission band was located
at the longer w a v e l e n g t h end of the spectrum, the
barxd was quite wide and of fairly low intensity. E x a m ples of the f o r m e r w e r e Bas (PO4) 2: E u +'~, BaMgP2OT:
Eu +2, and Ba2MgP4OI3:Eu +2, w h i l e e x a m p l e s of t h e
latter w e r e Ba2Mg(PO4)2:Eu +2 and both th e h i g h and l o w - t e m p e r a t u r e forms of Ba3P4013: Eu +2.
The location of the divalent e u r o p i u m emission band
in the spectrum is probably dependent on the coordination of the cations which the divalent e u r o p i u m is
replacing in the crystal lattice and also on the crystal
structure of the host compounds. Since the crystallographic structures of v e r y few of the fourteen compounds and polymorphs in the BaO-MgO-P20.~ system
have been d e t e r m i n e d and since the d e t e r m i n at i o n of
such crystal structures was not within the scope of this
work, no conclusions could be d r a w n w i t h regards to
the effects of different crystal structures on the luminescence of the divalent e u r o p i u m ion.
The emission data obtained from the divalent eu r o pium activation of the fourteen compounds and polymorphs in the BaO-MgO-P20~ system are s u m m a r i z e d
in Table III. Data on t h r e e r e f e r e n c e phosphors
BaSi.~Os:Pb, CaSiO3:Pb, Mn, and CaWO4 are also included for c o m p a r a t i v e analyses.
Acknowledgments
The author wishes to t h a n k Dr. K. H. Butler and
M. J. B. Thomas for t h e ir v a l u a b l e comments and
Position
V2
Peak Ht. I
Height
%
W i d t h ZncSiO4 : M n
Metaphosphates and gamma
Mg(PO~)u
E u .3 L i n e E m i s s i o n s
Ba(PC~)~
375 n m
31 n m
6.3 B a O - 1 . 0
Eu § Line Emissions
M g O - 2 . 7 P:O~
IGamma)
Ba~P~Ox:~ ( H i g h
T Form)
BaaP4Om ( L o w
T Form)
Ba.,_MgP~O13
Mg~P~O;
5-Ba.,.P207
c~-Ba~P20:
BaMgP20;
575 n m
Tetraphosphates
197 n m
Fluorescence
under2537A
compound
~
Weak red
5.0
Weak violet
-Weak red
7.4
F a i r lt. y e l .
437
138
18.0
M o d . It. b l u e
403
28
59.0
Good deep violet
Pyrophosphates
E u +~ L i n e E m i s s i o n s
--406
~
1~.4
402
45
103.0
Baj(POo~
Ba~Mg qPO~ }~
BaMg2r
~
Mg:~[POD ~
415
585
418
425
Orthophosphates
31
138.5
148
8.5
77
24.5
47
13.0
BaSi:~O~;Pb
CaWOt
CaSiO.~:Pb, M n
355
422
618
Re~erenee Phosphors
41
205.0
116
31.5
87
19.5
Weak red
Dead
F a i r lt. b l u e
Exc. deep violet
Exc.
Mod.
Mod.
Mod.
deep violet
It. y e l .
blue
blue-violet
Weak violet
Mod. blue
M o d . r e d or.
suggestions, and Mr. A l l en Rudis and Miss Marion
Skeadas for the spectral e n e r g y distribution and x - r a y
diffraction measurements.
Manuscript submitted May 23, 1968; revised m a n u script received J u n e 23, 1968. This p ap er was p r e sented at the Boston Meeting, May 5-9, 1968, as
Pap er 58.
A n y discussion of this paper will appear in a Discussion Section to be published in the J u n e 1969 JOURNAL.
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