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International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963

STUDIES ON THE GROWTH ASPECTS OF SEMI-ORGANIC
AMMONIUM BORODILACTATE: A PROMISING NEW NLO
CRYSTAL
T. Panchanathan1, S. Nalini Jayanthi2, P.Sagayaraj3, K. Thamizharasan4
1

Department of Physics, Vellayan Chettiyar Hr. Sec. School, Chennai, India
2
Department of Physics, AIHT, Chennai, India
3
Department of Physics, Loyola College, Chennai, India
4 Department of Physics, Sir Theagaraya College, Chennai, India

ABSTRACT
A new second order Non-linear optical semi organic single crystals of pure and Neodymium(Nd3+) doped
Ammonium borodilactate (ABL) has been grown by aqueous solution slow evaporation technique (SET). In the
present study, to improve the device characteristics of ABL crystals, metal dopant was incorporated into the
pure crystals. The grown crystals are Non- Hygroscopic and good transparent in the visible region, the
solubility of the grown crystals was found. The cell parameters were estimated by single crystal X-ray
diffraction pattern. UV- Vis-NIR spectrum was recorded to study the optical transparency of the grown crystal.
The pure and doped crystals were characterized by thermal studies. The mechanical behavior was studied by
Vickers micro hardness test, dielectric and photoconductivity studies were also carried out for the pure and
doped ABL crystals.

KEYWORDS: Solution growth, ABL, Micro Hardness, Dielectric, Photoconductivity.

I.

INTRODUCTION

Nonlinear optical (NLO) materials which can generate highly efficient second harmonic blue-violet
light are great interest for various applications including optical, optical computing, optical
information processing, optical disk data storage, laser remote sensing, colour display, etc.[1,2]. In
the recent past, there have been extensive efforts to develop new inorganic, organic and semi organic
nonlinear optical (NLO) materials that posses several attractive properties such as high threshold,
wide transparency range and high nonlinear coefficient which make them suitable for frequency
doubling [3, 4]. In view of this, there has been considerable interest in the synthesis of semi-organic
materials having high mechanical and thermal stability. Semi-organic materials gain importance over
inorganic materials because of their polarizability, wide transmission window and high damage
threshold [5]. The low temperature solution growth is an important technique because most of the
semi-organic non linear- optical crystals are being grown by this technique. Due to the inherent
limitation of these techniques, the size of the crystals grown by these methods is small.
In the present investigation, we report the growth of Neodymium (Nd3+) doped ammonium
bordilactate (ABL) along with pure ABL crystals by slow evaporation technique. The grown crystals
are subjected to single crystal X-ray studies to estimate the crystal structure and space group. The
content of the dopant was determined by ICP analysis. UV- Vis-NIR, thermal, micro hardness,
dielectric and photoconductivity studies were carried out from the grown pure and doped crystals.

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Vol. 6, Issue 1, pp. 298-303

International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963

II.

RELATED WORKS

The effect of sodium chloride, borax and boric acid of different concentrations on the growth rate of
ammonium pentaborate octahydrate crystals (APBO) was measured by O. Sahin et.al. [6]. The effect
of ammonium malate on the growth rate, structural, optical, thermal, mechanical, dielectric properties,
crystalline perfection and second harmonic generation (SHG) efficiency of ammonium dihydrogen
phosphate single crystals grown by the slow cooling method has been investigated by P. Rajesh et. al
[7]. They found SHG efficiency was enhanced by the dopant. Ammonium acetate doped ammonium
dihydrogen phosphate single crystals have been grown by slow cooling along with bidirectional seed
rotation method by P.Rajesh et.al.[8]

III.

EXPERIMENTAL PROCEDURE

3.1 Crystal growth
The synthesis of ammonium borodilactate with chemical formula (NH4)+ (C6H8BO6)- was done by
stoichiometric incorporation of ammonium carbonate, boric acid and lactic acid. Taken in the ratio
1:2:4. ABL salt was synthesized according to their relation.
(NH4)2 CO3 + H3BO3 + C6H6O3 →
(NH4) + (C6H8 BO6)3+
Nd doped ABL salt was also synthesized by adding 3 mole % of the dopant. To increase the purity
of the crystal, recrystalization was carried out using doubled distilled water more than three times.

3.2 Solubility Studies
The solubility of pure and Nd3+ added ABL in double distilled water was measured at different
temperature (30, 35, 40 and 45ºC) using a constant temperature bath of accuracy ± 0.01ºC. The
solvent and an excess amount of ABL were added to a 250ml glass crystallizer. Experiments were
repeated for several times at each temperature. Similar experimental procedure was followed for Nd 3+
at each temperature added ABL material. The solubility of pure and Nd 3+ added ABL in double
distilled water was plotted as a function of temperature (Fig.1). Fig.2 shows the photograph of as
grown pure and doped crystals in a period of 45 days.

Figure 1. Solubility curves of pure and Nd3+

Figure 2. Photograph of as grown (a) pure and (b) Nd 3+

doped ABL crystal

doped ABL crystal
crystal

3.3 Characterization analysis
The grown crystals of pure and doped ABL have been subjected to single crystal X-ray diffraction
studies using ENRAF NONIUS CAD-4 single crystal X-ray diffractometer with Cu K(λ=1.541Ǻ)
radiation. The structure of the grown ABL crystal was solved by direct method and retired by the full
matrix-least – squares technique using ‘SHELXL’ program. The optical absorption spectrum was
recorded for samples of about 4-6 mm thickness using a Varian carry 5E model dual beam
spectrometer in the wave length range from 200 to 2000 nm. Single crystals of pure and doped ABL
crystals were subjected to thermo gravimetric analysis (TGA) and differential thermal analysis (DTA)
simultaneously between 20˚C and 1400˚C in the nitrogen atmosphere at the heating rate of 10K/min
using STA 409˚C instrument. The electric constant was measured along the direction perpendicular to

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Vol. 6, Issue 1, pp. 298-303

International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963
the (010) face of low frequency at room temperature (28˚C). The single crystal (dimensions: thickness
1.04mm and area 8.5 mm2) using a LCR meter (HIOKI3532-50 LCR HITESTER). In the frequency
range 100Hz – 6MHz.

IV.

RESULT AND DISCUSSION

4.1 Single crystal XRD analysis
It is observed that both pure and doped ABL single crystals belongs to orthorhombic system with a
non-centrosymmetric space group C2221 with four molecules per unit cell (Z = 4). The lattice
parameters values of ABL are measured as a= 9.3464 Ǻ, b=11.9628Ǻ, c=8.5674 Ǻ and cell volume
V= 957.9134 Ǻ3 and agree well with the reported values [9]. There slight variations in the lattice
parameters and cell volume of the doped crystals. These variations may be due to the incorporation of
the dopant in the ABL crystal lattice.

4.2 Inductively Coupled Plasma Analysis
In order to determine the weight percentage of dopant in doped ABL crystal, 10mg of fine powder of
the doped crystal was dissolved in 100ml of triple distilled water. This prepared solution was taken for
the ICP analysis. The results obtained from ICP show that 2.16% of Nd3+ (216 µg/100ml) was present
in the solution. It is observed that the amount of dopant incorporated into the crystal lattice is below
its original concentration (3%) in the solution.

4.3 UV-Vis-NIR spectral analysis
UV-Vis-NIR spectrum was as shown in Fig.3. For optical application, especially for SHG, the crystal
must be transparent in the wavelength region of interest. The grown pure and Nd3+ doped ABL sample
shows high transparency (85%) in the range from 230 to 1300 nm and a sharp UV cut off wave length
observed at 230nm and 240nm for pure and doped ABL is due to - * transition in this
material.From the spectra, it is seen that doped ABL crystals have better lower cut-off wavelenghths
than the pure crystals. The high transmission in the entire visible region on short cutoff wave length
facilities it to be a potential NLO material for second and third harmonic of Nd: YAG laser.

Figure 3. Absorption spectrum of pure and Nd3+ doped ABL crystal

4.4. TGA and DTA studies
Fig.4 shows the resulting TGA and DTA traces of the pure and doped crystals. ABL was thermally
stable around 204.3 ˚C and 218.2˚C respectively. The sharp weight loss of the material starts around
204.3˚C.
The DTA trace of ABL shows that a sharp endothermic matching with the decomposition of ABL.
The Nd3+ doped ABL crystal shows the same features as that of pure ABL.

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Vol. 6, Issue 1, pp. 298-303

International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963

Figure 4. TGA and DTA curves of pure ABL crystal

4.5 Micro hardness studies

crystal

Micro hardness behaviour of the pure and doped crystals were tested by employing Vicker’s micro
hardness test on the (010) plane. Measurements were taken by varying the applied loads from 5 to 50
g. Micro cracks were developed at higher loads, therefore the maximum applied load was restricted to
50g only. The plot of variation of Vicker’s hardness number (HV) with applied load for (010) plane of
pure and doped ABL is shown in (Fig.5). From the plot, it is noted that the hardness number (H V) of
the crystal decreases with increasing load. This type of behaviour wherein the hardness number
decreases with increasing applied load is called normal indentation size effect (ISE). The workhardening coefficient ‘n’ is calculated using log P versus log d graph. The value of work hardening
coefficient, ‘n’ is found to be less than 2 for both pure and doped crystals. This further confirms the
normal ISE behaviour [10]. The hardness number HV has improved in the case of doped crystal.

Figure 5. Variation of HV with load for pure and Nd3+ doped ABL

4.6 Dielectric studiescrystal
The opposite parallel faces of the crystals were coated with high-grade silver paste placed between the
two copper electrodes and thus a parallel plate capacitor was formed. The capacitance of the sample
was measured by varying the frequency from 100 to 6MHz. The dielectric constant (εr) was calculated
on capacitance, electrode area, and sample thickness. Fig.6 shows the plot of dielectric constant (ε r)
verses applied frequency. The dielectric constant has high values in the lower frequency region and
then it decrease with the applied frequency. The dielectric constant has a high value of 6.4 at 100 Hz
and decreases to 2.7 at 6 MHz. The dielectric constant of materials may be due to the contribution of
all the four polarizations, namely, space charge, dipolar, electronic and ionic polarization, which
depend on the frequencies. The variation of dielectric loss with frequency is shown in Fig.7. The
dielectric loss has low value of 0.129 at high frequency (6MHz). The effect of inclusion of dopant is
found to decrease the dielectric constant. The behavior of doped crystal is very similar to that of
undoped crystal except having lower values of dielectric constant. The low value of dielectric loss at
high frequency for these samples suggest that samples possesses enhanced optical quality with lesser
defects and this parameter is of vital importance for NLO materials in their application [11].

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Vol. 6, Issue 1, pp. 298-303

International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963

Figure 7. Variation of dielectric loss with
frequency for pure and doped ABL single crystals

Figure 6. Variation of dielectric constant with
frequency for pure and doped ABL single
crystals

4.7 Photoconductivity Studies
Fig.8 and 9 shows the field dependence of dark and photo currents in doped and pure ABL crystals. It
is observed that both dark and photo currents of crystals increase linearly with the applied electric
field but the photo current of both pure and doped crystals is less than the dark current which is
termed as negative photoconductivity. The loss of water molecules can also lead to decrease in
conductivity. However, in the present case the contribution of water molecules to negative
photoconductivity is ruled out as the loss of water molecules for pure and doped ABL crystals begins
at 204.3˚C and 218.2˚C respectively. Hence, the negative photoconductivity in the present case is
attributed to the reduction in the number of charge carriers or their life time, in the presence of
radiation [12].

Figure 8. Field dependent photoconductivity of
doped ABL single crystals

V.

Figure 9. Field dependent photoconductivity of
pure ABL single crystals

CONCLUSIONS AND FUTURE WORK

Pure and Nd3+doped ABL crystals have been grown for pure and Neodymium (Nd3+) - added growth
solution by the slow evaporation method. The structure of the grown crystals confirmed with single
crystal X- ray analysis, it is obvious that the pure and Nd3+ doped ABL crystals retain the
orthorhombic structure and the calculated lattice parameter values are comparable with the reported
values of pure ABL. The presence of Nd3+ in ABL crystal was confirmed by inductively coupled
plasma analysis. The transparency nature of the crystal in the visible and infrared region that form the
absorption spectrum confirms the NLO property of the crystal. From Vickers microhardness studies,
the VHN value of this pure ABL crystal is less than that of the doped crystal, and revealed that the
micro hardness number decreases linearly with increasing load for both pure and doped. ABL crystals
were calculated and found to be less than two for both pure and doped crystals of ABL were
measured. At low frequency range both dielectric constant and dielectric loss are found to decrease

302

Vol. 6, Issue 1, pp. 298-303

International Journal of Advances in Engineering &amp; Technology, Mar. 2013.
©IJAET
ISSN: 2231-1963
with the increase of frequency. In general, ABL shows higher dielectric constant and dielectric loss
than its doped system. The crystals with low dielectric constant lead to minimum losses as they have
less number of dipoles per unit volume and hence doped crystals will be more useful for high speed
electro optic modulations as compared to pure crystals. Photoconductivity studies of both pure and
doped ABL crystals. It is clearly observed that both pure and doped crystals exhibit negative
photoconductivity.
Basic studies shows Pure and Neodymium (Nd3+) added crystals are suitable for high speed electro
optic modulation techniques. Further studies on Second Harmonic Generation, Photo Luminescence
analysis, DC conductivity measurements can lead to some concrete conclusion regarding the use of
this crystal in NLO devices.

REFERENCES
[1]. H.S. Nalwa, Seizo Miyata, Nonlinear Optics Molecules and Polymers,CRC Press NewYork, 1997.
[2]. P.N. Prasad, D.J. Williams, Introduction to Nonlinear Optical Effects In organic Moleculeas and
Polymers, John Wiley and Sons Inc. New York, USA,1991.
[3]. N. Vijayan, R. Ramesh Babu, R. Gopalakrishnan, P. Ramasamy,J.Cryst.Growth 267 (2004).
[4]. R. Mohan Kumar, D. Rajan Babu, D. Jayaraman, R. Jayavel, K. Kitamura, J.Cryst. Growth, 275 (2005)
1935.
[5]. R. Bairava Ganesh, V. Kannan, K. Meera, N.P. Rajesh,P.Ramasamy, J.Cryst.Growth, 282 (2005) 429.
[6]. Ö. Şahin, M. Özdemir, N. Genli, Journal of Crystal Growth, 270 (2004) 223-231.
[7]. P. Rajesh,P. Ramasamy, G. Bhagavannarayana, Journal of Crystal Growth, 311 (2009) 4069-4075.
[8]. P. Rajesh, K. Boopathi, P. Ramasamy, Journal of Crystal Growth, 311 (2011) 751-756.
[9]. K.Thamizharasan, S.Xavier Jesuraja, Francis P.Xavier, P. Sagayaraj, J. Cryst. Growth, 218 (2000) 323.
[10]. S. Dhanuskodi, P.A. Angeli Mary, J. Cryst. Growth, 253 (2003) 424.
[11]. M.D. Shahabuddin Khan, G. Prasad. G.S. Kumar, Cryst. Res. Tech, 27 (1992) K28.
[12]. V.N. Joshi, Photoconductivity, Marcel Dekker, New York, 1990.

AUTHORS
T. Panchanathan received his B.Sc., M.Sc., and M.Phil. in Physic from Madras University. He
is currently doing his Ph.D., in Bharathiyar University, Coimbatore. He has 2 years of teaching
experience in college and 20 years of teaching experience in school. He published more than 4
research papers in various National and International conferences.

S. Nalini Jayanthi received her B.Sc., Degree in Physics (2000), M.Sc., Degree in Physics
(2002), M.Phil., Degree in Physics (2003) from Bharathidasan University. She is currently
working as Assistant Professor in Anand Institute of Higher Technology, Chennai-603 103. She
has published more than 6 research papers in various National and International Conferences.
Her research interest includes Ultrasonics and Spectroscopy.
P. Sagayaraj received his Ph.D degree from Madras University (1996). He have 30 years of
teaching experience. Now he is working as Dean of Reasearch in Loyola College, Chennai. He
published more than 94 international research papers and 25 national research papers. He
published more than 180 national and international conference papers. He completed two
research projects and two other projects are undergoing. He guided 50 M.Phil., students and 21
Ph.D., research scholars/ Currently he is guiding 2 M.Phil., students and 8 Ph.D., research
scholars.
K. Thamizharasan received his Ph.D., degree from Madras University (2000). He has 30
years of teaching experience. Now, he is working as Associate professor and Head of Physics
department in Sir Theagaraya College, Chennai-21. He published more than 20 papers in
Nation/International conferences. He published nearly 25 papers in international Journals. He
guided nearly 15 M. Phil., students and guiding 5 Ph.D., scholars. His area of Interest is Crystal
growth.

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