Thermal dependence of the properties of cubic boron nitride crystal

Zainelabideen Y Mijbil,Mudar A Abdulsattar,Ahmed M Abdul-Lettif

doi:10.4236/ns.2011.32022

Zainelabideen Y Mijbil, Mudar A Abdulsattar + Show 1 more

Open Access

https://doi.org/10.4236/ns.2011.32022

Copy DOI

Journal: Natural science	Publication Date: Jan 1, 2011
Citations: 8	License type: CC BY 4.0

Affiliation: University of Babylon

Abstract

Lattice constant, total energy, cohesive energy, bulk modulus, speed of sound (υ), plasmon energy (Epl), valence charge distribution and energy bands of cubic boron nitride crystal have been calculated and studied as a function of temperature using self-consistent field tight binding method with complete neglect of differential overlap version 2 using 8-atom large unit cell approach. Our results illustrate that the increase of temperature leads to an increase of lattice constant, cohesive energy, and valence charge distribution at the atoms, whereas a decrease is obtained for bulk modulus, energy band widths, valence charge distribution in the intratomic distance, speed of sound, and the plasmon energy. The comparison with experimental and other theoretical results has showed an excellent agreement for the lattice constant, bulk modulus, cohesive energy, speed of sound, plasmon energy value and the valence band, whereas remarkable differences in charge distribution values, and the band gap are found. These differences are common in the results that depend on this type of calculation. Values for conduction band and speed of sound have not been found for comparison. Our relation for Epl-T fails but the υ-T relation is successful.

Highlights

The high account of hardness [1], melting point [2], high thermal conductivity [3] and band gap [4], resistance for oxidation as temperature increases[5] with inert state [6] low electrical conductivity [7], and no iron reaction [8]are all for sp3 [9] cubic boron nitride
We have presented two relations: one of them is for plasmon energy and the other is for speed of sound with temperature in order to simplify the calculations
1) TB-LUC-CNDO/2 method is preferred for wide range of calculations such as the lattice constant, cohesive energy and valence band etc

Summary

Introduction

The high account of hardness [1], melting point [2], high thermal conductivity [3] and band gap [4], resistance for oxidation as temperature increases[5] with inert state [6] low electrical conductivity [7], and no iron reaction [8]are all for sp3 [9] cubic boron nitride. It has amazing aspects [10] of multiuse [11,12] such as in polishing, cutting [13] and protection [14], and it has been the core for many studies [15,16,17,18] since its discovery in 1957 [19]

Objectives

Methods

Results

Conclusion