A Study of Some Optical Properties of Chromic Chloride(

Quest Journals Journal of Research in Humanities and Social Science Volume 5 ~ Issue 2 (2017) pp: 37-40 ISSN(Online) : 2321-9467 www.questjournals.org Research Paper

A Study of Some Optical Properties of Chromic Chloride(đ??‚đ??Ťđ??‚đ??Ľđ?&#x;‘ )Thin Film Ahmed Gadem Mohamed Ali1, 3,Montasir Salman Elfadel Tyfor2, 3 1

Department of Chemistry, Faculty of Education, Peace University, Sudan Department of Physics Faculty ofEducation in (Al-Hasahisa), Gezira University Sudan 3 FacultyofScience &Arts Al-BAHA University KSA.

2

Received 07Feb. 2017; Accepted22Feb. 2017 Š The author(s) 2017. Published with open access at www.questjournals.org ABSTRACT: In this work,the optical properties of chromic chloride(đ?‘Şđ?’“đ?‘Şđ?’?đ?&#x;‘ )thin film prepared at different thickness has been measured. The relationship between transparency, absorbance and photon energy for the prepared samples has been studied. It has been found, the behavior of curves is the same for each samples.Moreover, it has been observed thatThe best fit of theexperimental curve to a band gap function was obtained for đ?‘› = 2 to direct bandgap energy values the obtained values are 1.531 eV, 1.533 eV,1.536 eV, and 1.539 eV for dip the rated of đ??śđ?‘™ (0.0 - 0.25 – 0.50 and 0.75 ) respectively.

Keywords:Film thickness, Energy band gap,(đ?‘Şđ?’“đ?‘Şđ?’?đ?&#x;‘ ) , Optical Properties.

I. INTRODUCTION The physical properties plays important role in material science, it has been able to interpret many of the phenomena related to materials, The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states [1] Physical properties include appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others [2]. In this work we study the Absorption coefficient derived from (đ??‚đ??Ťđ??‚đ??Ľđ?&#x;‘ )thin film with different thickness and Transmission spectra for (đ??‚đ??Ťđ??‚đ??Ľđ?&#x;‘ )samples with different thin film thickness to describe the optical properties for(đ??‚đ??Ťđ??‚đ??Ľđ?&#x;‘ ), many devices are used to study the optical properties of materials, but the problem is how to choose effective devices for measurement of these properties. The optical measurements comprise measuring the absorbance and transmittancewith range (350 - 900 nm), in the current study, by using (UV mini 1240 spectrophotometer.

II. CHROMIC CHLORIDE(đ??‚đ??Ťđ??‚đ??Ľđ?&#x;‘ ) STRUCTURE AND APPLICATIONS

Anhydrous chromium (III) chloride agrees the YCl3 structure, with đ??śđ?‘&#x;3 + occupying two thirds of the octahedral interstices in alternating layers of a pseudo-cubic close packed lattice of đ??śđ?‘™âˆ’ ions. The absence of cations in alternate layers leads to weak bonding between adjacent layers. For this reason, crystals of CrCl3 cleave easily along the planes between layers, which results in the flaky (micaceous) appearance of samples of chromium (III) chloride.[3][4], Chromium(III) chloride is used as the precursor to many organ chromium compounds, for example chromium, Phosphine complexes derived from CrCl3 catalyze the dimerization of ethylene to 1-hexene.[5][6], One niche use of CrCl3 in organic synthesis is for the in situ preparation of chromium(II) chloride, a reagent for the reduction of alkyl halides and for the synthesis of (E)-alkenyl halides. The reaction is usually performed using two moles of CrCl3 per mole of lithium aluminum hydride, although if aqueous acidic conditions are appropriate zinc and hydrochloric acid may be sufficient, Chromium(III) chloride also used as a Lewis acid in organic reactions, for example to catalyze the nitroso Diels-Alder reaction.[7]

*Corresponding Author: Ahmed Gadem Mohamed Ali 1 Department Of Chemistry, Faculty Of Education, Peace University, Sudan

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A Study Of Some Optical Properties Of Chromic Chloride(đ?‘Şđ?’“đ?‘Şđ?’?đ?&#x;‘ ) Thin Film‌

Fig (1) shows the relation between absorbance and photon energy

CrCl CrCl CrCl CrCl

5.04 4.48

0.00 0.25 0.50 0.75

Absorpation ( % )

3.92 3.36 2.80 2.24 1.68 1.12 0.56 1.507 1.518 1.529 1.540 1.551 1.562 1.573 1.584 1.595

hď ľ ( eV )

Fig (2) shows the relation between transparent and photon energy

0.61

Transimission ( % )

0.00 -0.61 -1.22 -1.83

CrCl CrCl CrCl CrCl

-2.44 -3.05

0.00 0.25 0.50 0.75

-3.66 -4.27 1.507 1.518 1.529 1.540 1.551 1.562 1.573 1.584 1.595

hď ľ ( eV )

Fig (3) shows the relation between reflection and photon energy

0.44 0.00

Reflaction ( % )

-0.44 -0.88 -1.32

CrCl CrCl CrCl CrCl

-1.76 -2.20

0.00 0.25 0.50 0.75

-2.64 -3.08

1.507 1.518 1.529 1.540 1.551 1.562 1.573 1.584 1.595

hď ľ ( eV )

*Corresponding Author: Ahmed Gadem Mohamed Ali

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A Study Of Some Optical Properties Of Chromic Chloride(đ?‘Şđ?’“đ?‘Şđ?’?đ?&#x;‘ ) Thin Film‌ Fig (4) show the relation between absorption coefficient and photon energy

Absorpation Coefficient ď Ąď€ ( cm-1 )

1.20x107

CrCl 0.00 CrCl 0.25 CrCl 0.50 CrCl 0.75

1.08x107 9.60x106 8.40x106 7.20x106 6.00x106 4.80x106 3.60x106 2.40x106

1.507 1.518 1.529 1.540 1.551 1.562 1.573 1.584 1.595

hď ľ ( eV )

(5) show the relation between extinction coefficient and photon energy

CrCl CrCl CrCl CrCl

Extincetion Coefficient ( k )

7.02 6.24 5.46

0.00 0.25 0.50 0.75

4.68 3.90 3.12 2.34 1.56 0.78 1.507 1.518 1.529 1.540 1.551 1.562 1.573 1.584 1.595

hď ľ ( eV )

Fig (6) the optical energy gap (Eg) value of Cr Cl 3.24x1014

( ď Ąhď ľ )2 ( eV.cm-1 )2

2.88x1014

Eg CrCl 0.00 = 1.531 eV EgCrCl 0.25 = 1.533 eV

2.52x1014

Eg CrCl 0.50 =1.536 eV

2.16x1014

Eg CrCl 0.75 = 1.539 eV

1.80x1014 1.44x1014 1.08x1014 7.20x1013 3.60x1013 0.00 1.316 1.344 1.372 1.400 1.428 1.456 1.484 1.512 1.540

hď ľ ( eV )

*Corresponding Author: Ahmed Gadem Mohamed Ali

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A Study Of Some Optical Properties Of Chromic Chloride(đ?‘Şđ?’“đ?‘Şđ?’?đ?&#x;‘ ) Thin Film‌

III. RESULTS AND DISSECTIONS Fig (1) shows the relation between absorbance and photon energy, we found the behavior of curves is the same for each curves. The rapid increase of an absorption in the low energy and sudden increase in special energy, this is refer to electronic transition, and this increase is continuous with the increase of photon energy, absorbance value increased with rated of đ??śđ?‘™ increase.

Fig (2) shows the relation between transparent and photon energy, we had been found rapid decrease in low energies and sudden decrease in special energies and it continuous with decrease in high energy, rated of đ??śđ?‘™increase refers to the decrease in transparent value.

The reflection were calculated depended energy safe law using the relation R + T+ A = 1 ‌‌‌‌‌‌‌‌‌‌‌‌. (1) When: R- Reflection, T- TransmitionFig (3) shows the relation between reflection and photon energy. we had been found rapidly increase in reflection value .until to arrive to peak, then it reduce from high energy because of less absorption in low energies from energy gap Transmition decreasing due to reflection increasing using the relation (1) .At high energies from energy gap, the a absorbance is increasing, this cause the reduce in reflection, and the upper corresponding energy gap value (1.55-1.6)eV. Increasing threated of đ??śđ?‘™ due to minor change in to peak curves, it is shifted low energies.

The absorption coefficient đ?›ź was calculated using 2.303 đ?‘Ľđ??´ đ?›ź= (2) đ??ż

Where Îą is absorption coefficient L optical axes length on the sample Fig (4) shows the plot of absorption coefficient as a function of photon energy. It could be seen from the graphthat đ??śđ?‘&#x; đ??śđ?‘™ had maximum absorptions between 1.54 and1.56 eV In depended on conclusion absorption value in relation (1), extinction coefficient was measured by using relation đ?›źđ?œ† đ?‘˜ = (3) 4đ?œ‹

Were K is Extinctioncoefficient,Îť is Wave length And the fig (5) show the relation between extinction coefficient and photon energy. It was found that the decreasing at extinction coefficient value with increase the rated of đ??śđ?‘™ because of decreasing absorption coefficient value with increase of the rated of đ??śđ?‘™ like relation (2) The optical energy gab was calculated using the well-knownTauc’s relation: đ?›ź = đ??´ (â„Žđ?œ? − đ??¸đ?‘”) đ?‘›â„ŽáżĄ(4) Wheređ??´ is a constant, â„Žđ?œ? is the photon energy, and đ?›ź isthe absorption coefficient, while đ?‘› depends on the nature ofthe transition. For direct transitions đ?‘› = 1/2 or 2/3, whilefor indirect ones đ?‘› = 2 or 3, depending on whether theyare allowed or forbidden, respectively. The best fit of theexperimental curve to a band gap function was obtained for đ?‘› = 2 to direct bandgap energy values the obtained values are 1.531 eV, 1.533 eV,1.536 eV, and 1.539 eV for dip the rated of đ??śđ?‘™ (0.0 - 0.25 – 0.50 and 0.75 ) respectively Fig (6). There is a slight increasein band gap as the dip times increases.

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*Corresponding Author: Ahmed Gadem Mohamed Ali

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