Bulk Modulus and Cohesive Energy of Zn, Cd, and Hg Monochalcogenides and Oxides

INTRODUCTION

II VI group semiconductor AX (A= Zn, Hg; X = O, S, Se, Te) are currently 3 under intense investigations driven by their unusual properties just as their possible a applications in electronic and opto-electronic devices as ultrasonic transducers, ‗surface acoustic wave devices oxygen sensors. There has likewise been a developing interest in the investigation of these materials under high tension conditions, motivated by the need of synthesizing new solids with targeted physical properties (1,2,3). For understanding an assortment of physical phenomena, it is important to know the stretch and bulk E properties of crystals. The studies on structurah phase transition, metallisation, cohesive, elastic and bulk properties under high pressure have attracted quite interest in Zn, Cd, and Hg chalcogenides over the most recent twenty years due to their applications in light emitting diodes (LED) and laser diodes (4). Structural what's more, electronic property of AX compounds have been ii: experimentally and theoretically during the past few years, however, the bonding, elastic and bulk property of these mixtures have been less studied (5). Amlost all the AX compounds crystallize either in zinc blend or wurtzite structures, ZnS, ZnSe, ZnTe, CdS, CdTe, crystallize in both zinc blend, and HgSe, HgTe, crystallize in zinc blend structure only Hgs crystallize in zinc blend and hexagonal Cinnabar Structure, and ZnO, has wurtzite structure, CdC has NaCl structure, HgO has Cinnabar structure (6-7). The common and dominant feather of these structures is that each atom of one kind is tetraheddrally bonded to four atoms of by the other element. In zinc blend these tetrahedral are arranged in a cubic type structure ' whilst they are in a hexagonal type structure. Indeed the centers of similar tetrahedral are arranged in a face-centered hexagonal closed packed (hcp) array in the later (8). Neumann (9) considered the mass modulus of salt halides regarding I spectroscopically defined covalency. We present in this note our examinations a Zn, Cd, and Hg, monochalcoginides and oxides. In this introduction, we assess the honiOpolar hole, ionic hole, normal hole, and henceforth the iconicity of these mixtures utilizing the modified Phillips and Van Vechten hypothesis (10, 11). The assessed estimations of Phillips iconicity, and Neumann scaling law (9) give us the estimations of mass moduli and firm energy for these mixtures.

The term iconicity intrinsically characterizes electronegativity, bond length, electron density (12), flexible constants, bulk molulus, cohesive energy, effective charge etc. The correlationships of iconicity had been arising from the isomer shift. Parameters used in Mossbaur effect. Phillips described the new deprition based on band structure. As indicated by the modified Phillips and Van Vechten hypothesis (P V V theory) (13, 14, 15), the average gap Eg is given by Where Eh and Ec are the contributions of homopolarity and hetropolarity to the AB bond, ZA, ZB are the valence states of atoms A & B, respectively Ks the Thomas- ‗ Fermi screening parameter, and b is an adjustable parameter given by b ‘4 .089-NC2,where Nc is the average monochalcogenides.

The evaluated values of iconicity are used in the followmg relation proposed by Neumann for the evaluation of the bulk modulus: Where n has the value 1.147 and the factor B0 is given by Here b0 = 4.134 and b1 = 2.877, and fc is the covalency fc=(1-fi). Using available crystallographic data (1, 17-23) for these compounds and following the modified PVV theory, the values of iconicity are calculated. The calculate value of iconicity are shown in table 1. The calculated values of iconic1ty and the relations ' (4) and (5) lead us to decide the values of bulk modulus. The determlned values are shown in Table-2. The comparison between our calculated values and known experimental & theoretical values (1, 29-30) shows good agreement. Cohesive Energy: Using the Phillips iconicity the cohesive energy (31) is given as Where fl is the iconicity, Tm is melting temperature, k is adjustable parameter has values -3.63x102. The result obtained by equation (6) is found in better agreement. with experiment values (1, 24—26) compared to obtained.

The modified PVV hypothesis has been applied to Zn, Cd, and Hg monochalcogenides. The assessed estimations of iconicity and the Neumann connection give us the estimations of mass moduli and durable energy for these monochalcogenide semiconductors. The great understanding between our determined qualities with the detailed exploratory and hypothetical information verifies the legitimacy of the above basic methodology for the assurance of mass moduli and durable energy.

The creators might want to express gratitude toward Dr. S.C. Goyal& Dr. Seema Gupta (Department of Physics, Agra College, Agra) for proposing the first program _ and proceeded with direction throughout work and for some, supportive conversations identifying with the understanding of the outcomes. I'm likewise appreciative to executive of Central Library, IlT Delhi. Focal Library JNU Delhi Library of deptt. Science, AMU Aligarh, for their consideration of allowing me to utilize their material for this reason. Material from different sources has been incorporated for culmination.

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Department of Physics, Agra College, Agra (UP), India dvsingl102@gmail.com