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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/13564

Title: Indirect phase transition of TiC, ZrC, and HfC crystal structures
Authors: Abavare, E.K.K.
Dodoo, Samuel N. A.
Uchida, Kazuyuki
Nkurumah-Buandoh, George K.
Yaya, Abu
Oshiyama, Atsushi
Keywords: carbides
density functional theory
phase transitions
Issue Date: 2016
Publisher: Wilye online libray
Abstract: We have performed first-principles calculations to analyze the electronic structures, static, and dynamical structural stabilities of the pressure-induced phase transformation of refractory compounds (transition-metal carbides) from NaCl-type (B1) to CsCl-type (B2) via zinc-blende phase using the plane-wave pseudopotential approach in the framework of the generalized gradient approximation (GGA) for the exchange and correlation functional. The ground-state properties, equilibrium lattice constant, bulk moduli, and band structures are determined for the stoichiometry of the compounds and compared with known experimental and theoretical values. We find that the phase-transition pressure for the indirect phase transition from B1→B2 via zinc-blende structure is about 17-fold for TiC, 12-fold for both ZrC and HfC, respectively, when compared with the direct phase transition. Calculated phonon instability exists for the CsCl-B2 phase, which can prevent the structures from forming and contrary to the zinc-blende and the NaCl-B1 phases. The band dispersion and electronic density of states for B1 and B2 crystal phases were explored and found to indicate metallic character in contrast with the zinc-blende phase, which has a pseudogap opening in the bandgap region suggesting a semiconducting property and also a frequency gap in the phonon spectrum.
Description: This article is published in Wiley online and is also available at DOI 10.1002/pssb.201552793
URI: 10.1002/pssb.201552793
Appears in Collections:College of Science

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