Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 1069-1074
Published Online November 2012 (http://www.SciRP.org/journal/jmmce)
Growth and Characterization of β-Alanine Oxalate—
A New Organic Single Crystal
S. Lincy Mary Ponmani1, P. Selvarajan2*, N. Balasundari3, D. Jencylin3
1Department of Physics, St. Mother Theresa Engineering College, Tuticorin, India
2Department of Physics, Aditanar College of Arts and Science, Tiruchendur, India
3Department of Physics, Infant Jesus College Of Engineering, Tuticorin, India
Received July 6, 2012; revised August 10, 2012; accepted August 17, 2012
ABSTRACT
A new organic single crystal of β-Alanine Oxalate (BAO) has been grown from solution by slow evaporation technique.
Transparent, colourless crystals of size upto 11 × 9 × 4 mm3 were obtained. Formation of the new crystal has been con-
firmed by single crystal XRD and FTIR spectra. The grown crystals have been subjected to powder X-ray diffraction
studies to identify the crystalline nature. Single crystal X-ray diffractometer was utilized to measure unit cell parameters
and to confirm the crystal structure. BAO belongs to monoclinic system with lattice parameters a = 22.335 Å, b = 5.697
Å, c = 13.993 Å, α = 90˚, β = 115.37˚, γ = 90˚, and volume of the unit cell, V = 1609 Å3. The functional groups are con-
firmed by FTIR vibrational analysis. Optical transmission spectra revealed the optical properties of the grown crystal.
Transmission spectrum reveals that the crystal has low UV cut-off of 205 nm and has a good transmittance in the entire
visible region enabling its use in optical applications. There is no absorption in the entire visible region. Mechanical
strength of the grown material is tested by hardness studies. The value of hardness increases when the applied load is
increased.
Keywords: Amino Acid; X-Ray Diffraction; Lattice Parameters; FTIR; Transmittance; Microhardness; Organic Crystal;
SHG
1. Introduction
Amino acids and their complexes are the organic or
semi-organic materials that have attracted great attention
due to their ability in ease of processing in the assembly
of optical devices. The complete understanding of the
optical properties of amino acid crystals, as well as other
organic crystals, still requires more attention [1-7].
3-Aminopropionic acid is commonly known as β-alanine
with molecular formula C3H7NO2 and in which the
amino group is at the β-position from the carboxylate
group [8-10]. Supplementation with β-alanine has been
shown to increase the concentration of carosine in mus-
cles, decrease in fatigue in athletes and increase total
muscular work done. β-alanine is purely a synthetic
amino acid and it is a positional isomer of L-alanine
[11,12]. It forms crystalline complexes with organic,
inorganic acids or salts. In this paper, we report for the
first time the growth and characterization of a new or-
ganic crystal viz. β-alanine oxalate and the results are
presented.
2. Experimental Procedure
2.1. Growth
β-alanine and oxalic acid were taken in the molar ratio of
1:1 and the calculated amounts of β-alanine and oxalic
acid were dissolved thoroughly in de-ionized water at
room temperature. A saturated solution was prepared and
the solution was filtered using a Whatmann filter paper.
For the growth, the filtered solution in a beaker was
allowed for slow evaporation. Good colourless, trans-
parent single crystals were obtained within a period of 15 -
20 days. The grown crystal is displayed in Figure 1. The
size of a grown crystal is observed to be 11 × 9 × 4 mm3.
Re-crystallization was carried out twice to improve the
purity of the sample.
2.2. Instrumentation
Powder X-ray diffraction measurement was taken using
an automated X-ray powder diffractometer(PANalytical)
with nickel filtered, monchromated CuKα radiation (λ =
1.5406 Å). The XRD pattern was taken after the grown
crystal was crushed into fine powder. The Fourier
Transform Infrared (FTIR) spectrum was recorded using
*Corresponding author.

S. L. M. PONMANI ET AL.
1070
Figure 1. Photograph of BAO crystal.
SHIMADZU 8400 S. The sample was prepared by pres-
sing BAO with KBr into a pellet form. The UV-Vis
spectrum of BAO crystal was recorded in the wavelength
range 190 nm - 1100 nm using Perkin Elmer Lambda 35
spectrometer.
3. Results and Discussion
3.1. Solubility
The solubility of BAO was measured in the temperature
range from room temperature to 55˚C. A volume of 50
ml of water was taken in a container and re-crystallized
salt was added. The temperature of the solution was
maintained above the chosen constant temperature and
continuously stirred using a magnetic stirrer to ensure
homogeneous temperature and concentration throughout
the entire region of the solution. Once the saturation was
reached, the equilibrium concentration of the solute was
analyzed gravimetrically [13]. The experiment was car-
ried out for various temperatures from room temperature
to 55˚C in steps of 5˚C and the solubility curve was
drawn and it is presented in the Figure 2. The solubility
curve indicates that BAO crystal has positive temperature
coefficient of solubility.
3.2. XRD Analysis
From the single crystal X-ray diffraction analysis, it is
found that the BAO crystallizes in monoclinic system
with lattice parameters a = 22.335 Å, b = 5.697 Å, c =
13.993 Å, α = 90˚, β = 115.37˚, γ = 90˚, and volume of
the unit cell, V = 1609 Å3. In order to study the crystal
structure of BAO the grown sample was subjected to
powder X-ray diffraction studies with a high resolution
PANalytical X’pert PRO diffractometer. Powder XRD
pattern of BAO sample is shown in Figure 3. All the
reflections of powder XRD pattern of this work were
indexed using the TREOR and INDEXING software pac-
kages following the procedure of Lipson and Steeple [14].
The values of 2θ, hkl values and d-values etc are pre-
sented in the Table 1.
3.3. FTIR Analysis
FTIR study is used to identify the functional groups of
the samples. In the FTIR spectrum (Figure 4), the band
at 2927 cm–1 is on the high frequency side of the broad
absorption. The deformation vibration of the water mole-
cules was found at 1525 cm–1. The broad bands due to
the in-plane bending vibrations (δ OH) of the O-H···O
bending bonds are located at 1128 cm–1. The out-of-plane
bending modes of the O-H···O hydrogen bonds (γ OH)
were found at 918 and 781 cm–1. The νa COO mode gives
rise to the absorption observed at 1627 cm–1. The strong
band 1402 cm–1 is attributed to the νs COO– mode. The
carboxylic groups scissoring modes (δ COO–) are ex-
pected in the region of 500 - 750 cm–1. Weak bonds are
visible at 648 cm–1. The complete absorption bands and
their assignments for the grown BAO sample are pro-
vided in the Table 2.
3.4. UV Visible Spectral Studies
The UV-Vis analysis was made between 190 and 1100
nm, which covers near ultraviolet (200 nm - 400 nm),
Visible (400 nm - 800 nm) and then Far-Infrared (800 -
1200 nm) regions. The plot of % of transmittance versus
30 35 40 45 50 55
15
20
25
30
35
40
45
50
Concentration (g/100 ml)
Temperature (
o
C)
Figure 2. Solubility curve of BAO crystal.
5 1015202530354045505560657075
0
1000
2000
3000
4000
5000
6000
7000
8000
-425
303
312
-223 -315 -421
-503
112
-125
-522
022
120
-404
410
Counts
2 theta (degrees)
Figure 3. Powder XRD pattern of BAO crystal.

S. L. M. PONMANI ET AL. 1071
Table 1. The values of 2θ, hkl and d-values for BAO crystal.
2θ (degrees) d (cal) Å d (obs) Å hkl
13.81695 6.32176 6.40386 002
15.86843 5.58079 5.58028 –401
16.67197 5.525853 5.31310 –111
17.98822 4.96093 4.92718 210
19.90698 4.43471 4.45638 –501
21.07639 4.2145 4.21169 003
22.47157 3.92216 3.95326 112
23.09904 3.85449 3.84724 –503
23.67687 3.77703 3.75467 410
24.81665 3.60886 3.58474 –213
25.2999 3.49944 3.51735 –511
26.07443 3.41713 3.41461 –404
27.36215 3.25637 3.25676 –504
27.84415 3.19245 3.20147 312
28.62254 3.16088 3.11615 004
29.15924 3.03416 3.06000 303
29.92589 2.97881 2.98333 –314
30.71410 2.92249 3.90855 213
31.11264 2.86315 2.87219 412
31.80475 2.82054 2.81125 120
32.47677 2.74613 2.75468 –221
33.05522 2.70392 2.70770 204
34.5039 2.59704 2.59752 022
35.01030 2.53712 2.56084 –421
35.75416 2.50847 2.50925 –315
36.94224 2.43091 2.43124 –223
37.83470 2.38321 2.37591 –522
2θ (degrees) d (cal) Å d (obs) Å hkl
38.93460 2.31125 2.31129 015
39.42319 2.28173 2.28376 123
40.63857 2.20793 2.21822 –324
41.11312 2.19436 2.19371 521
41.87151 2.15957 2.15571 422
45.54444 1.99303 1.99003 –425
47.12085 1.94149 1.92707 –125
48.70484 1.86774 1.86803 –231
49.35870 1.84537 1.84481 415
50.10238 1.81872 1.81915 032
52.06304 1.75284 1.75516 –333
53.19255 1.71831 1.72052 530
54.36710 1.68578 1.68610 524
55.62736 1.65202 1.65084 –134
57.32108 1.60938 1.60602 425
58.65760 1.57055 1.57258 –335
60.39421 1.53397 1.53144 525
63.95376 1.45802 1.45452 434
67.40114 1.38826 1.38826 –342
68.25821 1.37290 1.37290 –442
4500 4000 3500 3000 2500 2000 1500 1000500
0.4
0.3
0.2
0.1
0.0
1128
1014
918 827
486
401
707
1218
1251 1332
1402
1525
1627
1716
2362
2927
3089
3280
Transmittance (AU)
Wavelength (cm
-1
)
Figure 4. FTIR spectrum for the grown crystal of BAO.
Table 2. FTIR assignments for BAO crystal.
Wave number in cm–1 Band assignments
3280
3089
2927
1716
1627
1525
1458
1429
1402
1332
1251
1218
1128
1062
1014
981
918
827
781
707
648
486
401
νa H2O
νs H2O
ν N-H···O
νa C = O (β-alanine)
νa C = O (acid)
δ H2O
δ C H2/δ N-H···O
δ C H2
νs COO-(acid)
ω C H2
ν CO-H
ν CO-H
δ OH, ν C H2-C H2
ν C-H
ρ C H2
Ρ NH3+
Ρ NH3+ , γ OH
ν C-C
γ OH
δ COO
δ COO–
ω COO–
δ COO–
wavelength is shown in Figure 5. The absorbance is not
registered until the wavelength 205 nm is reached from
1100 nm. At 205 nm, a sharp fall of transmittance was
observed indicating a single transition in the near UV
region. The nearly sharp fall in transmittance at 205 nm
suggests nearly similar distribution of energies among all
molecules of β-alanine oxalate single crystal, which oth-
erwise will yield a gradual decrease in the transmittance
from the longer wavelength to 205 nm. The plot of % of
absorbance vs wavelength is shown in Figure 6. From
the graph, it is observed that there is no absorption in the
entire UV and visible region.
3.5. Thermal Studies
Differental Thermal (DTA)/Thermaogravimetric (TG)

S. L. M. PONMANI ET AL.
1072
200 300 400 500 600 700 800 9001000110
0
-10
0
10
20
30
40
50
60
70
80
90
100
110
Transmittance
wavelength (nm)
analyses were carried out on the BAO samples to look
for possible phase transitions and to determine the melt-
ing point. The thermal analysis was carried out in the
temperature between 30˚ and 1000˚C. The TG/DTA re-
sponse curve of BAO is shown in Figure 7. The DTA
curve shows a major endothermic peak observed at
around 172˚C and it may attributed to the melting of the
material. The sharp DTA peak at 545˚C is attributed to
the volatilization of the material the other endothermic or
exothermic peaks observed, coincide exactly with the
decomposition observed in the TGA curve. In the TGA
trace, there is a major weight loss of 77% starting at
about 182˚C and ending at 353˚C. It is due to the de-
composition and volatilization of the compound. The next
weight loss of about 13% occurs between 353˚C and
595˚C shows that the decomposition is almost complete.
There is one more weight loss between 595˚C and 980˚C
is due to the decomposition of the residue that is left over
after the major weight loss which corresponds to 5%.
Figure 5. UV-vis-NIR transmittance spectrum for the
grown BAO crystal.
200 300 400 500 600 700 800 90010001100
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
A
nm
In order to confirm the melting and volatilization of
the compound without decomposition, DSC analysis was
carried out between 20˚C and 1000˚C. The DSC trace is
shown in Figure 8. The exotherm at 172˚C is assigned to
melting of the material and a sharp endothermic peak at
548˚C is assigned to volatilization based on the results
obtained with DTA curve.
3.6. Hardness Measurements
Hardness is the resistance offered by a material to plastic
deformation caused by scratching or by indenta tion. In
ideal circumstances, measured hardness value should be
Figure 6. Absorbance spectrum of BAO crystal
Figure 7. TGA and DTA curves of BAO sample.

S. L. M. PONMANI ET AL. 1073
Figure 8. DSC curve of BAO sample.
independent of applied load. But in practice, load de-
pendence is observed. In this work, the selected smooth
surface of a BAO crystal was used for microhardness
measurements at room temperature, using a Vickers mi-
cro hardness tester (mhp-100) attached to an incident-
light microscope (Leitz-Wetzler microscope) keeping the
indentor at right angles to the crystal plane for 10 s in all
cases. An average of 10 diagonal length of the indenta-
tion mark was measured using an optical micrometer
eyepiece at a magnification of 500:1. The Vickers micro-
hardness number was calculated using the relation Hv =
1.8544 P/d kg/mm2 where P is the applied load and d is
the diagonal length of the indentation impression [15,16].
A plot of Hv versus load is shown in Figure 9. As the
load is increased, there is an increase in the hardness.
The increase of microhardness with increasing load is in
agreement with the Indentation Size Effect (ISE) as re-
ported in the literature [17].
3.7. Second Harmonic Generation (SHG) Test
The SHG test for the grown BAO crystal was carried out
by using powder Kurtz and Perry technique [18]. The
crystal was ground into a homogenous powder and
densely packed between two transparent glass slides. A
Q-switched Nd:YAG laser beam of wavelength 1064 nm
(pulse width 6 ns) was allowed to strike the sample cell
normally. A sample of potassium dihydrogen phosphate
(KDP) also powdered and was used for the same experi-
ment as a reference material in the SHG measurement.
20 30 40 50 60 70 80 90100110
32
34
36
38
40
42
44
46
48
50
Hv ( kg/mm2)
Load P (g)
Figure 9. Plot of Hv versus load for BAO crystal.
From the experiment, it is noticed that there is no green
light (no SHG emission) emitted from the sample and
this gives the conclusion that the grown BAO crystal has
zero second order susceptibility coefficient.
4. Conclusion
β-alanine oxalate crystals were grown from aqueous so-
lution by slow evaporation technique at room tempera-
ture. The X-ray diffraction studies confirm the mono-
clinic structure of the grown crystals. The FTIR analysis
confirms the presence of various functional groups. The
near zero transmittance below the cut off wavelength and
the high degree of transparency illustrates the optical
quality of the grown samples. As seen in the spectrum,
there is no significant absorption in the range 250 nm -

S. L. M. PONMANI ET AL.
1074
1100 nm. Thermal behavior of the BAO sample was
studied by employing TGA, DTA and DSC analysis. The
hardness study reveals that BAO crystal can only with-
stand low loads and at higher loads, it can break and
damage and it proves that BAO crystal is a soft material.
The present result shows that the grown BAO crystal
does not emit green light when the light from Nd:YAG
laser is passed onto the sample.
5. Acknowledgements
The authors like to thank the staff members of RRL
(Trivandrum), CECRI (Karaikudi), Crecent Engineering
College (Chennai), St. Joseph’s College (Trichy) and M.
K. University (Madurai) for having helped us to carry out
the research work.
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