A computational study of layered and superhard carbon-nitrogen material

• Main Author: Manyali, George Simiyu
• Format: Others
• Language: en
• Published: 2015
• Subjects: Nitrides.; Carbon compounds.; Synthetic hard materials.; Solid state electronics.; Dielectric devices.
• Online Access: http://hdl.handle.net/10539/16867

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. August 2014. === The process of the computational discovery of materials for future technologies is a combination of numerical techniques and general scientific intuition to select elements and combine in order to form novel types of materials. Modern ab initio methods based on density functional theory are capable of predicting with a high level of accuracy the most stable ground state atomic configurations of any given material. Once the ground state configurations are established, the electronic, optical and mechanical properties of the novel bulk nitrides may be determined. Electronic properties of C3N4, CN2, SiN2, GeN2, C2N2(NH), Si2N2(NH), Ge2N2(NH) and Sn2N2(NH) are analysed by computing the Kohn-Sham band structures. The optical properties are investigated by calculating the real and the imaginary parts of the frequency-dependent dielectric constant. The mechanical properties are determined by calculating elastic constants, Young’s modulus, Poisson’s ratio, Vickers hardness, shear and bulk moduli.