Available online at www.scholarsresearchlibrary.com
Scholars Research Library
Archives of Applied Science Research, 2012, 4 (3):1453-1461
(http://scholarsresearchlibrary.com/archive.html)
ISSN 0975-508X
CODEN (USA) AASRC9
Growth, Structural and Spectral Studies on pure and doped
Ammonium Dihydrogen Phosphate (ADP) single crystals
V Renganayaki,* D Syamala and R Sathyamoorthy
PG Department of Physics, Dwaraka Doss Goverdhan Doss Vaishnav College, Chennai 600 106
______________________________________________________________________________
ABSTRACT
Single crystals of pure, hydrogen borate and potassium nitrate doped Ammonium Dihydrogen Phosphate (ADP)
were grown from aqueous solutions, employing slow evaporation technique at room temperature. The grown
crystals were subjected to powder X–ray diffraction studies to study their structural characteristics. FTIR spectral
analysis was performed to identify the presence of various functional groups in the crystals. The UV–Visible–NIR
spectral analysis was carried out to confirm the improvement in the transparency of the ADP crystal on the addition
of boric acid and potassium nitrate.
Key words: ADP, Boric acid, Potassium nitrate, Crystal growth, FTIR, X–ray diffraction, UV–Vis –NIR.
______________________________________________________________________________
INTRODUCTION
Studies on Ammonium dihydrogen phosphate (NH4H2PO4) crystal still attracts interest because of their unique non–
linear optical, dielectric, piezoelectric and antiferroelectric properties and their variety of uses such as electro-optic
modulators, harmonic generators and parametric generators. Several research works have been carried out on pure
and doped ADP crystals. [1–5] In recent years, efforts have been taken to improve the quality, growth rate and
properties of ADP by employing new growth techniques and also by the addition of organic, inorganic and semi
organic impurities.[6–8] Inorganic non linear optical materials have large optical susceptibilities, inherent ultrafast
response times, and high optical thresholds for laser power. [9,10] With an aim of finding new useful materials for
academic and industrial use, an attempt has been made to modify ADP crystals by adding 1 mole % by weight of
hydrogen borate and potassium nitrate in the mother solution of ADP. In this work, the structural, spectral and
optical properties of hydrogen borate doped and potassium nitrate doped ADP crystals against pure ADP have been
studied and reported.
MATERIALS AND METHODS
Crystal Growth
Single crystals of pure and doped ADP were grown from supersaturated solution at room temperature by natural
evaporation process using AR grade samples of ADP, hydrogen borate and potassium nitrate. The dopants were
added separately with pure ADP solution, each in definite molecular ratio, namely ADP: X (X being dopant) in the
molar weight 1:0.01ratio. Each solution was stirred for three hours using magnetic stirrer and filtered using
Whatman filter paper. The filtered solution was transferred to borosil glass beaker. It was porously sealed and placed
in a dust free atmosphere for slow evaporation. The pH of the solution was noted as 4. The grown crystals were
1453
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
harvested after a period of 30 days. All the grown crystals were colourless, stable and transparent. Figure 1, 2 and 3
show the as grown crystals of pure and doped ADP. The crystals were characterized using FTIR, UV-VIS-NIR
spectroscopic techniques and powder XRD technique.
Characterization
The FTIR spectra of pure, hydrogen borate doped and potassium nitrate doped ADP crystals were recorded by KBr
pellet technique using Perkin Elmer FTIR Spectrophotometer in the range 4000-400 cm-1 at St. Joseph College,
Trichy. Powder X-ray diffraction pattern was recorded using a Philips X pert PRO X-ray diffractometer with CuKα
(λ=1.5418Å) radiation at University of Madras. The optical properties of the grown crystals were studied using
Shimadzu UV-1601 visible spectrometer in the wavelength region 200-1100 nm at Ethiraj College, Chennai.
RESULTS AND DISCUSSION
FTIR Spectroscopic study
In the present work, FTIR spectra of pure and doped ADP crystals were compared and the complete vibrational band
assignments were carried out. The comparative FTIR spectral studies confirm the presence of borate ion and the
nitrate ion in the respective doped crystals. In the present work, the FTIR spectra of pure and doped ADP single
crystals were presented in Figures 4, 5 and 6 respectively.
In spectrum of pure ADP, the broad band around 3250 cm-1 was due to the O-H vibrations of water, P-O-H group
and N-H vibrations of ammonium. The band at 2387cm-1 was assigned to hydrogen bond. [11] The broadness was
due to the hydrogen bonding interaction with adjacent molecules. The O-H bending vibration gave the peaks at
1706, 1642cm-1. The peak at 1409cm-1 was due to the bending vibration of ammonium. The very strong band at
1292cm-1 was due to the combination of the asymmetric stretching vibration of PO4 with lattice. The peaks at 1098
and 910cm-1 represented P-O-H vibrations. The medium bands at 560, 405cm-1 were due to PO4 vibrations.
In the spectrum of hydrogen borate added ADP crystal, the band appearing at 3100cm-1 included O-H vibrations of
water and N-H vibrations of ammonium. [10] The sharp peaks at 1292 and 1409cm-1 in the spectrum of ADP were
shifted to 1288 and 1417cm-1 and they became medium intensity bands due to the presence of borate ion. The peak
at 1417cm-1 was due to B-O terminal asymmetric stretching and the symmetric stretch of B-O vibrations lied in the
region 910cm-1 and 1100cm-1. [9] The peak at 1706cm-1 in pure ADP due to bending of water has broadened and has
become a medium intensity band at 1697cm–1, showing that the moisture content has been lost due to the addition of
boric acid in the ADP crystal.
In the FTIR spectrum of potassium nitrate added ADP crystal, there was a shift in the peak positions of P-O-H and
PO4 vibrations compared to the pure ADP crystal. Also the inorganic nitrate salts exhibit a very strong band at
1410-1350cm-1 due to asymmetric NO3 stretching. [12] Here the presence of a very strong band at 1403cm-1
indicated the presence of nitrate ion in the lattice of the potassium nitrate doped ADP crystal. Also the bands due to
hydrogen bonding had a change and were present at 2452 and 2358cm-1 in the doped crystal. Table 1 represents the
FTIR vibrational band assignments of the pure and the doped ADP crystals.
Powder XRD Analysis
Powder X-ray diffraction study was conducted to verify the single phase nature of the samples. Figures 7 and 8
show the powder XRD patterns of hydrogen borate and potassium nitrate doped ADP crystals. Well defined Bragg
peaks were obtained at specific 2θ angles indicating that crystals were ordered. The powder XRD studies were done
at University of Madras using SEIFERT JSO Debyeflex 2002 model X-ray diffractometer. The X radiation used
was copper (K-Alpha 1) radiation (λ=1.54056Å) operating at a voltage of 40 KV and a current of 20 mA. The
scanning rate was maintained at 1.6°/min over a 2θ range of 10-70° employing the reflection mode for scanning.
The figures 7 and 8 indicate the sharp peaks and hence the crystalline nature of the grown crystals. There is a slight
shift in the diffracted peaks in the XRD pattern of potassium nitrate added ADP crystals. When compared to that of
pure ADP, the intensity of the diffracted peaks was found to vary in both the XRD patterns of doped ADP crystals.
However, there were no other phases emerging besides the tetragonal system. The powder XRD showed that the
original tetragonal structure is maintained and the boric acid and potassium nitrate have entered into the lattice of
ADP crystal.
1454
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
Figure 1 Photograph of as grown pure ADP crystal
Figure 2 Photograph of as grown hydrogen borate doped ADP crystal
Figure 3 Photograph of as grown potassium nitrate doped ADP crystal
1455
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
FT IR SPECT RUM
Date: 10/1/2011
Spectrum Name: SAP.sp
100.0
90
80
70
60
50
%T
40
3835.31
2387.44
560.31
30
20
10
3132.14
1706.40
1292.34
1409.19
1098.80
910.10
0.0
4000.0
3000
2000
1500
1000
400.0
cm-1
SAP.pk
SAP.sp 1801 4000.00 400.00 3.39 82.43 4.00 %T 10 1.00
REF 4000 54.34 2000 38.96 600
3835.31 44. 37 3132.14 3. 39 2387.44 40.02 1706.40 15.15 1409.19 5.86
1292.34 17. 29 1098.80 13.16 910.10 13.59 560.31 40.60
Figure 4 FTIR spectrum of pure ADP crystal
Optical transmission Spectral Studies
Single crystals of ADP are mainly used for optical applications. The study of the optical transmission range of the
grown crystals is thus very important. Pure, hydrogen borate doped ADP and potassium nitrated doped ADP crystal
plates with a thickness of 2mm without any antireflection coating were cut and used for optical measurements. The
UV-Visible-NIR transmission spectra were recorded using Shimatzu UV-Visible Spectrophotometer in the range
200nm to 1200nm. From the spectra in the Figure 9, it was observed that both the doped ADP crystals and pure
ADP crystals showed good transmittance in the entire visible and NIR regions. The overlay UV-Vis NIR spectra
clearly shows that, the addition of hydrogen borate and potassium nitrate have enhanced the optical quality of ADP
crystals. [13] Both the doped ADP crystals have minimum absorption in the entire region between 200-1200nm.
1456
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
ACIC
St.Joseph's College ( Autonomous )
T richy-2
FTIR SPECTRUM
Date: 10/1/2011
Spectrum Name: SBC.sp
100.0
90
80
70
459.08
60
50
557.97
%T
40
2435.95
30
1697.21
1288.05
1100.16
910.52
1417.26
20
10
3100.03
0.0
4000.0
3000
2000
1500
1000
400.0
cm -1
SBC.pk
SBC.sp 1801 4000.00 400.00 5.04 96.14 4.00 %T 10 1.00
REF 4000 69.66 2000 46.39 600
3100.03 5.04 2435.95 40.51 1697.21 33.99 1417.26 28.24 1288.05 34.26
1100.16 30.00 910.52 30.90 557.97 55.52 459.08 67.26
Figure 5 FTIR spectrum of hydrogen borate doped ADP crystal
Table 1 Vibrational band assignment of pure and doped ADP single crystals.
Pure ADP
3132
2387
1706
1642
1409
FTIR Frequency (cm-1)
Hydrogen borate doped ADP Potassium nitrate doped ADP
3100
3133
2452
2435
2358
1697
------1639
1417
1403
1292
1288
1302
1098
910
560
460
1100
910
557
459
1098
904
552
452
Band Assignment
O-H stretching, P-O-H stretching, N-H vibrations of Ammonium
Band due to hydrogen bond
O-H bending vibration
O-H bending water
Bending vibration of ammonium
Combination of the asymmetric
Stretching vibration of PO4 with lattice
P-O-H vibrations
P-O-H vibrations
PO4 vibrations
PO4 vibrations
1457
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
FTIR SPECTRUM
Date: 10/1/2011
Spectrum Name: SKN.sp
100.0
90
3951.15
80
70
3844.04
452.49
3737.04
60
2452.55
2358.65
50
552.20
%T
40
1302.91
30
904.60
1098.59
1639.35
20
3412.73
10
0.0
4000.0
1403.29
3133.65
3000
2000
1500
1000
400.0
cm -1
SKN.pk
SKN.sp 1801 4000.00 400.00 6.67 91.91 4.00 %T 10 0.50
REF 4000 76.33 2000 66.59 600
3951.15 73.73 3844.04 70.62 3737.04 68.31 3412.73 24.91 3133.65 6.67
2452.55 66.43 2358.65 63.78 1639.35 30.88 1403.29 8.83 1302.91 38.22
1098.59 34.96 904.60 37.52 552.20 57.08 452.49 71.91
Figure 6 FTIR spectrum of potassium nitrate doped ADP crystal
1458
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
Figure 7 Powder XRD of hydrogen borate doped ADP crystal
Figure 8 Powder XRD of potassium nitrate doped ADP crystal
1459
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
Figure 9 Overlay UV–Visible–NIR spectra of pure and doped ADP single crystals
CONCLUSION
The effect of hydrogen borate and potassium nitrate dopants on the growth of ADP from supersaturated solutions
has been investigated experimentally by measuring optical trans- mission, functional groups and X ray diffraction
measurements. The presence of dopants in ADP solution was found to increase the optical transmission. The
enhancement of optical transmission of doped ADP crystals highlights their prospects of application as NLO
materials.
REFERENCES
[1] N. Zaitseva, L. Carman, Prog. Crystal. Growth. Charact. , 2001,43, 1.
[2] P. Rajesh, P. Ramasamy, Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy, 2009, 74, 210.
[3] 3. P. Rajesh, P. Ramasamy, G. Bhagavannarayana, Binay Kumar, Current App. Phy., 2010, 10,
1221.
[4] N. Joseph John, C.K. Mahadevan, Mater Manuf Process., 2008,23, 809.
[5] N.P. Rajesh, C.K. Lakshmana Perumal, P. Santhana Raghavan, P. Ramasamy, Cryst. Res. Technol., 2001, 36, 55.
[6] K. Sankaranarayanan, P. Ramasamy, J. Cryst. Growth., 2005, 280, 467.
[7] P. Rajesh, P. Ramasamy, C.K. Mahadevan, J. Cryst. Growth., 2009, 311, 1156.
[8] P. V. Dhanaraj, G. Bhagavannarayana, N. P. Rajesh, Mat. Chem. Phy., 2008, 112, 490.
[9] R. Ananda Kumari, Indian J. Pure Appl. Phys. , 47, (2009) PP.369-371.
[10] T. Ananthi, S. Mary Delphine and Abdul Wahab Almusallam., Recent Res Sci Tech., 2011, 3,32.
[11] Rajesh. P, Ramasamy, J. Cryst. Growth., 2009, 311, 3491.
[12] Ferdousi Akhtar and Jiban Podder, J. Crys. Process. Tech., 2011, 18, 25.
1460
Scholars Research Library
V Renganayaki et al
Arch. Appl. Sci. Res., 2012, 4 (3):1453-1461
______________________________________________________________________________
[13] T. Josephine Rani, Fernando Loretta, P. Selvarajan, S. Ramalingom and S. Perumal, Recent Res Sci Tech.,
2011,3, 69.
1461
Scholars Research Library