Presentation 1

Submitted byMs. SUREKA.G Reg No : 21010

Under the Guidance of Dr. Sr. GERARDIAN JEYAM, Ph.D

HOLY CROSS COLLEGE (AUTONOMO

NAGERCOIL – 4

GROWTH AND CHARACTERIZATION OF UREA - THIOUREA MIXED

CRYSTAL

ABSTRACTCrystal growth and characterization studies found to

be a fascinating field in advancing Science and Technology.

Pure and Mixed Crystals are of wide application in different areas of developments.

Characterization studies were carried out by collecting powder x-ray diffraction pattern.

Assigned the miller indices and calculated the lattice parameters using the PXRD data verified the result with that of expected structure.

FT-IR spectroscopic analysis carried helps to determine the chemical functional groups present in the sample.

UV studies were carried for both pure and mixed crystals.

INTRODUCTIONCrystals are the unacknowledged pillers of modern technology.

It used for semiconductors, superconductors, polarizers.

The metal complex of thiourea is called semi organics. It includes the advantages of both organics and inorganic materials.

There are two stages involved in this project

Growth of pure and mixed crystals using slow evaporation method.

Characterization studies.

MATERIALS AND METHODS

PROPERTIES OF UREAIUPAC name : UreaMolecular formula : CH4N2OMolar mass : 60.06 g/mol

USES Fertilizer, fuel in power generation, Urine therapy

PROPERTIES OF THIOUREAIUPAC name : ThioureaMolecular formula : CH4N2SMolar mass : 76.12 g/mol

USES Sulphur sources for making semiconductor cadmium sulfide nanoparticle

SOLUTION PREPARATION

Pure urea-thiourea and urea-thiourea mixed crystals were crystallized by the slow evaporation method.

pure urea, pure thiourea, urea-thiourea (1:9) mixed crystal, (9:1) mixed crystal, (1:3) mixed crystal, (2:3) and (3:2) mixed crystals respectively were grown by using deionized water.

40 ml saturated solution of urea and thiourea was prepared at 40C with agitation by a magnetic stirrer continuously for about two hours.

Then heat was applied using a heater-cum-stirrer and the obtained supersaturated solution was filtered. The above 40ml supersaturated solution of urea and thiourea was transferred into a beaker labeled A and B.

C is obtained by pouring supersaturated solution of urea-thiourea (1:9) stirred continuously for about two hours while D,E,F,G crystallites are prepared by the same process by adding different compositions.

Nucleation ie) tiny crystals nucleates at the centre of the beaker within two weeks, large crystals were obtained after 10 days.

Photograph of the grown crystals

RESULTS AND DISCUSSION

The grown crystals were characterized by powder. X-ray diffraction analysis (XRD) to confirm the identity of a solid material and determining crystallinity and phase purity.

In the present study, 6 sets of XRD were taken for urea – thiourea pure and mixed crystals.

These studies were compared with JCPDS values

In XRD pattern the intensity in counts is taken along Y-axis and 2θ along X-axis.

X – RAY DIFFRACTION ANALYSIS

XRD pattern of as grown urea crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameters

(A)

4.704 15 001 4.71042 055

a = 5.662

b = 5.662

c = 4.710

3.9916 999 110 4.00117 100

3.6137 237 101 3.62243 11.97

3.0435 254 111 3.05021 17.54

2.8225 68 200 2.83115 7.35

2.5245 114 210 2.53086 15.84

2.4202 94 201 2.42660 8.14

2.3520 16 002 2.35517 0.99

XRD pattern of as grown thiourea crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameters

(A)

4.6061 60 011 4.62810 6.48

a = 7.486

b = 8.566

c = 5.501

4.4173 807 101 4.47009 75.50

4.2680 999 020 4.28307 100

3.0895 590 201 3.09246 77.24

2.050 192 211 2.95519 27.61

2.8143 420 220 2.85846 41.94

2.7355 60 002 2.75027 12.94

XRD pattern of 1:9 mixed crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameters

(A)

4.6061 60 011 4.64585 8.24

a = 7.495

b = 8.595

c = 5.508

4.4173 807 101 4.48687 77.96

4.2680 999 020 4.29772 100

3.0895 590 201 3.09970 87.88

2.9050 192 211 2.96106 30.54

2.8143 420 220 2.86489 52.43

2.7355 60 002 2.75439 15.41

XRD pattern of 1:3 mixed crystal as grown thiourea crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameters

(A)

4.6061 60 011 4.52059 77.46

a = 7.509

b = 8.657

c = 5.527

4.4173 807 101 4.32869 80.78

3.0895 590 201 3.11075 95.37

2.9050 192 211 2.97703 40.86

2.8143 420 220 2.88111 75.08

2.7355 60 002 2.76369 15.09

2.5243 221 031 2.54863 46.81

2.4603 385 112 2.49097 57.86

XRD pattern of 2:3 mixed crystal as grown thiourea crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameter

s (A)

4.6061 60 011 4.64467 6.50

a = 7.488

b = 8.594

c = 5.506

4.4173 807 101 4.48583 75.55

4.2680 999 020 4.29721 100

3.0895 590 201 3.09899 81.18

2.050 192 211 2.96073 30.03

2.8143 420 220 2.86430 51.62

2.7355 60 002 2.75347 11.61

2.5243 221 031 2.53799 37.88

XRD pattern of 3:2 mixed crystal as grown thiourea crystal

FROM JCPDS FROM PRESENT WORK

d-spacing (A)

Int hkld-spacing

(A)

Relative intensity

(%)

Lattice parameters

(A)

4.6061 60 011 4.61661 6.14

a = 7.482

b = 8.548

c = 5.497

4.4173 807 101 4.46160 95.74

4.2680 999 020 4.27413 41.95

3.0895 590 201 3.08937 55.06

2.050 192 211 2.95075 31.37

2.8143 420 220 2.85694 34.03

2.7355 60 002 2.74859 9.14

2.5243 221 031 2.53269 21.85

FOURIER TRANSFORM INFRARED SPECTRAL ANALYSIS

It was used to analyze qualitatively the presence of functional groups in grown crystals.

The FTIR spectra are recorded in the region 400-4000cm-1

It is used to calculate the absorbance value. Absorbance A = log

Where, To, Ts from the FTIR spectrum

It is also used to calculate the composition of the mixed crystals.

A1 = a1x + b1 (1-x)

Where, A1 absorbance value of mixed crystals.a1 absorbance value of pure urea crystals.b1 absorbance value of pure thiourea crystals.x finding the composition value.

WAVE

NUMBE

R

(cm-1)

TS TO

ABSORBANC

E VALUE

A=Log(TO/TS)

3401.88 5.01 56 1.048

2937.07 48.32 80 0.218

2353.52 92.48 98 0.025

1703.92 29.01 42 0.160

1635.01 31.52 78.5 0.396

1375.92 22.81 62.5 0.437

1233.08 48.24 65 0.129

1065.51 26.01 89 0.534

FTIR spectrum of urea crystal

FTIR spectrum of thiourea crystal WAVE

NUMBER

(cm-1)

TS TO

ABSORBANCE

VALUE A=Log

(TO/TS)

3714.58 25.09 34 0.131

3519.45 25.87 27 0.018

3286.92 20.09 22 0.039

2353.25 14.36 18.2 0.102

2114.68 14.81 20.1 0.132

1816.65 35.73 50.2 0.147

1611.53 6.47 13 0.303

721.82 23.45 34.2 0.163

627.78 17.23 18. 0.037

FTIR spectrum of 1:9 mixed crystal WAVE

NUMBER

(cm-1)

TS TO

ABSORBANCE

VALUE A=Log

(TO/TS)

2888.08 13.47 16 0.074

2677.95 12.27 20 0.212

2359.51 21.48 27 0.099

2116.42 19.86 40 0.304

1816.84 47.76 68 0.153

1595.95 5.70 17 0.474

1075.33 6.78 11.2 0.217

711.89 40.37 43 0.027

FTIR spectrum of 9:1 mixed crystal WAVE

NUMBER

(cm-1)

TS TO

ABSORBANCE

VALUE A=Log

(TO/TS)

3445.30 12.93 21 0.210

3345.77 16.72 24 0.212

2806.38 81.05 89.1 0.041

2651.78 84.18 92.3 0.039

1620.05 8.10 35 0.635

1462.13 16.73 82 0.690

789.22 89.52 98 0.039

724.20 84.19 92.5 0.040

FTIR spectrum of 1:3 mixed crystalWAVE

NUMBER

(cm-1)

TS TO

ABSORBANCE

VALUE A=Log

(TO/TS)

3444.09 6.31 15 0.376

2948.68 70.81 84 0.074

2103.19 93.89 98 0.018

1748.05 70.07 74.3 0.025

1590.14 25.54 88.2 0.538

1354.17 62.45 94.4 0.179

1242.49 67.03 95 0.151

1056.16 89.49 100 0.048

Comparison of FTIR bands of urea – thiourea mixed crystals

PROPORTIONSUREA-THIOUREA MIXED CRYSTAL

EARLY REPORTEDBAND

ASSIGNMENTSTHIOUREA CM-1 UREA CM-1

1:9 3319 3376 - as NH2

1595 1627 1683 s (NH2)

1381 1417 - as (C=S)

1075 1089 - s (C-N)

711 740 - s (C=S)

9:1 3445 - 3435 as NH2

3345 3376 - as NH2

1674 - 1683 s NH2

1620 1627 - s NH2

1462 - 1471 as CN

1:3 3444 - 3435 as NH2

1590 1627 - s NH2

1354 1417 - as C=S

1056 1089 - s (C-N)

2:3 3355 3376 - as NH2

3275 3280 - s NH2

3160 3167 - s NH2

1593 - 1683 s NH2

1416 1417 - as C=S

1082 1089 - s (C-N)

ULTRA VIOLET-VISIBLE SPECTRAL STUDIES

The optical absorption and transmission spectra were recorded for urea – thiourea mixed crystal.

The spectra were recorded in the wavelength region from 190 to 1190 nm using lambda 35 spectrometer.

All the mixed crystals have low absorbance in the visible region.

The cut off wavelength of absorbance for all the mixed crystals have 330 nm and 1:3 mixed crystal has 332 nm.

SUMMARY AND CONCLUSIONS

Crystals are grown artificially everyday and are more concerned to discover new materials for the purpose of academic and industrial uses, as the need of single crystals is increased in solid state device, ‘scientists’ interests have turned from pure crystals to impurity (dopant) added and mixed single crystals.

In this project crystal growth studies have been carried out on supersaturated aqueous solutions of urea mixed with thiourea in different concentrations.

The crystals were characterized by XRD in which the lattice parameters a, b, c were calculated and compared with the standard JCPDS values, X-ray diffraction confirms that the grown crystals belongs to orthorhombic group

The peaks in the FTIR spectra pure, shows the presence of two amine (-NH2) group and C=S bonds. From the FTIR spectra, we calculate the composition of the mixed crystal. It is found that the estimated composition well agreed with original composition.

UV studies (ie) optical absorbance and transmittance studies have been carried out for the transparent crystals. It has high transmittance in the visible region. Therefore it is used in Opto electronics.