Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 25-27). Also available via the Internet.

MSc., Faculty of Science, University of the Witwatersrand, 2011 / Materials are modeled by the ab-initio plane wave pseudopotential methods using density functional theory. In this work, we are seeking new ultrahard with enhanced elastic and mechanical properties, thermal stability as well as hardness which might be of advantage over known traditional materials (diamond and cubic boron nitride). Structural, elastic and electronic properties of the advanced metal nitrides M2N3 and their ternary phases were investigated using both the local density approximation (LDA) and the generalized gradient approximation (GGA). The relative stability of the ternary phases with respect to their constituent mixtures is computed. Results obtained are compared with the available experimental and theoretical data. To gain more information concerning the elastic properties of these hypothetical materials, we also computed the charge densities of the binary and ternary phases. From these calculations suggestions are made as to how the elastic properties vary from those of known hard materials.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--Georgia State University, 2008. / Title from file title page. Nikolaus Dietz, committee chair, Brian Thoms, A. G. Unil Perera, Xiaochun He, committee members. Electronic text (215 p. : col. ill.) : digital, PDF file. Description based on contents viewed on July 14, 2008. Includes bibliographical references (p. 209-215).

Thesis (Ph. D)--Ohio State University, 2002. / Title from first page of PDF file. Document formatted into pages; contains xxx,198 p.: ill. (some col.). Includes abstract and vita. Advisor: Leonard J. Brillson, Dept. of Electrical Engineering. Includes bibliographical references (p. 188-198).

No description available.

Nitrides of late transition metals possess interesting properties leading to different technological applications, yet, due to many factors, synthesis and reliable characterization of the physical properties of these materials constitute a big challenge. In this work, we present a detailed firstprinciples investigation of the structural, the electronic and the optical properties of the bulk crystalline MNx (where M = Pd, Pt, Cu, Ag or Au; and x = 1/3, 1 or 2) and ZnN. The studied structural properties include energy-volume equation of state (EOS), equilibrium lattice structural parameters, cohesive and formation energies, relative phase stabilities, bulk modulus and its pressure derivative. By means of the enthalpy-pressure EOS, some possiblepressure-induced structural phase transitions are carefully examined. Electronic properties of the energetically most stable phases are investigated via the analysis of their band structure and their total and partial densities of states (DOSs). The frequency-dependent optical constants (absorption coefficient, reflectivity, refractive index, and energy-loss spectrum) of some phases are derived from the calculated frequency-dependent microscopic dielectric tensor. Our calculations of the structural and the electronic properties are based on density functional theory (DFT) within the projector-augmented wave (PAW) formulation and the generalised-gradient approximation (GGA) to the exchange-correlation functional. In order to improve the calculated electronic structure, and to investigate the optical spectra, we carry out expensive GW0 calculations within the the random-phase approximation (RPA) to the dielectric tensor. Obtained results are discussed within the employed theoretical methods of calculations. Whenever possible, our obtained results are compared with experiment and with previous theoretical studies. We report the discovery of some possible low-energy competitive phases which are more stable at zero pressure than the synthesized and other hypothetical structural phases. To the best of our knowledge, our calculated optical spectra may be considered as the first, and thus, the most accurate, calculations within the many-body perturbation GWA calculations, so far.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy

No description available.