This ppt has been done for the Academic Writing course. In this presentation , the growth of undoped and glycine doped L-alanine cadmium chloride crystals and results of various studies about the grown crystals were discussed.

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2. Application Number: ccb57cabe46c11e9bb5c616fdd4df6ae
BY
Dr.M.Malathi
Assistant Professor,
Department of Physics,
Seethalakshmi Achi College For Woman,
Pallathur – 630 107
Sivagangai District,
Tamilnadu.
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3. presentedby
Dr.M.MALATHI
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4. contents
 Introduction
 Objectives of the work
 Samples and equipments
 Synthesis and solubility
 Growth of crystals
 Various studies
 Summary and conclusion
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5. INTRODUCTION
Solids
Crystalline
Single Crystal
Poly Crystal
Non-crystalline
(Amorphous)
Crystal
An ideal crystal is one, in which elementary building blocks and the
atoms are arranged regularly in a space lattice with specific
geometrical symmetry elements and the surroundings of an atom
would be exactly the same as the surroundings of every similar atom.
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6. Amino acids
An amino acid mainly contains a carboxylic group and
an amino group and the amino acids form the building
blocks of the protein structure.
Amino acids are classified on the basis of their
acidic/basic nature, chemical structure, nutritional
requirement and relative position of amino acid and
carboxylic acid groups.
The importance of amino acids in NLO applications is
due to the fact that the amino acids have chiral
symmetry and crystallize in noncentro-symmetric
space groups.
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7. Synthesis of the samples
 To obtain undoped LACC sample, L-alanine and analar grade
Cadmium chloride monohydrate were taken in 1:1 molar ratio.
 To obtain the glycine doped LACC samples, 5wt%, 10wt%,
15wt% of glycine were added into the solutions of L-alanine
separately.
 These glycine doped samples are called as LACCG5,
LACCG10, LACCG15.
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8. GROWTH OF CRYSTALS IN THE PRESENT WORK
 Single crystals of undoped and doped LACC were grown by
solution method with slow evaporation technique using the
saturated solutions of the relevant synthesized salts.
 The grown crystals are non-hygroscopic, stable, colourless
and transparent. The external appearance of undoped LACC
crystals seems to be different when compared to that of the
doped crystals.
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9. a) Undoped LACC crystal
b) 5 wt% of glycine added
LACC crystal
c) 10 wt% of glycine
added LACC crystal
d) 15 wt% of glycine
added LACC crystal
Harvested crystals of undoped
and glycine doped LACC crystals
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10. Fourier Transforminfrared (FTIR) studies
From the obtained FTIR Spectra of the samples it is
observed that NH2 groups of L-alanine and L-proline molecules in
the samples are protonated by COOH group giving rise to NH3
+.
In the samples, the carboxylic acid group is present as carboxylate
ion and amine group exists as ammonium ion.
The spectra of the samples are similar except some absorption
peaks/bands are slightly shifted or broadened due to doping of
glycine into LACC samples.
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11. Dielectric properties
Measurement of dielectric constant (εr)
 Doping of LACC with glycine crystals is found to increase dielectric
constant appreciably at low frequencies. When LACC crystals are doped
with organic impurities, the concentration of charged defects increases in the
crystal lattices and hence space charge polarization increases and leads to
increase in dielectric parameters like dielectric constant and dielectric loss.
 The increase in dielectric constant for the doped crystals may be due to
frittering of domains due to incorporation of impurities in the lattice.
 The increase of dielectric constant as the temperature increases in the
samples is due to the increase of the space charge polarisation due to
thermally generated carriers.
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12. Measurement of dielectric loss factor
Like dielectric constant, the values of dielectric loss also
decrease with the increase of frequency and increase with the
increase of temperature.
The low value of dielectric loss at high frequency reveals
the high optical quality of the crystals with lesser defects, which
is the desirable property for NLO applications.
The charged defects in the doped LACC crystals are the
responsible for increase of the dielectric parameters and the
increase of loss factor with the temperature.
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13. Determination of AC conductivity
It is observed from the results that the conductivity values
increase for glycine doped LACC crystals and this is due to
increase of dielectric constant and loss factor as the samples are
doped.
Doping of LACC crystals with the organic dopants like
glycine leads to increase of the charged carriers and hence the
conductivity increases for the doped samples of this work.
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14. Activation energy
The plots of σac versus1/T for the undoped and doped
LACC samples at 1000 Hz are observed.
The obtained values of the activation energy (Eac) are
tabulated and it is observed that activation energy decreases
for impurity added crystals.
Since the charge carriers are more in the doped
samples, the conductivity is more and hence the activation
energy is observed to be less.
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15. Summary and conclusions
 A Glycine doped L-alanine cadmium chloride crystals were successfully
grown by solution method at room temperature using L-alanine, glycine and
cadmium chloride reactants. The FTIR spectra of pure and doped LACC
crystals were recorded and various assignments related to the vibrational
frequencies of the functional groups have been identified. Fourier transform
IR spectra of pure and doped LACC crystals were recorded in the range 400-
4000 cm-1 employing a Perkin-Elmer spectrometer in the form of solid
dispersed in KBr pellet technique.
 From the results, it is observed that NH2 groups of L-alanine and L-proline
molecules in the samples are protonated by COOH group giving rise to NH3
+
,the broad envelope in the higher wave number region between 3400 and
2900 cm-1. The functional groups such as NH3
+, OH, COO, CH2, CCN, C-C
etc present in the samples have been identified by FTIR studies. Dielectric
constant, dielectric loss and hence AC conductivity values were measured
using an LCR meter at different frequencies and temperatures. High values
of dielectric constant and loss factor at low frequencies are observed for all
the samples of this work and this may be due to presence of space charge
polarization.
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16.  The dielectric parameters like dielectric constant and dielectric loss factor
are found to be decreasing with increase of frequency and these values are
observed to be increasing with increase of temperature of the samples.
Doping of LACC with glycine is found to increase dielectric constant and
loss factor appreciably. The low value of dielectric loss at high frequency
reveals the high optical quality of the crystals with lesser defects, which is
the desirable property for NLO applications.
 AC conductivity values of the samples have been determined using the data
of dielectric constant and loss factor and the results show that the
conductivity increases when LACC crystals are doped with the organic
dopants like glycine. Using the values of conductivity, activation energy
has been calculated for all the samples and the activation energy of the
doped crystals is found to be low compared to that of pure LACC crystals.
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17. ACKNOWLEDGEMENT
 The authors like to thank the supported works from
various research centers such as M.K. University (Madurai),
M.S.University (Tirunelveli), St Joseph College (Trichy) and
Crescent Engineering College (Chennai). Also the authors
are thankful to the management of Aditanar College of Arts
and Science, Tiruchendur, St.Jude’s College, Thoothoor
and Scott Christian College, Nagercoil for the
encouragement given to us to carry out the research.
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18. REFERENCES Arun K.J., S. Jayalekshmi, 2008. Growth and Characterization
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