Ab Initio Computations of Electronic, Mechanical, and Thermal Properties of ZrB₂ and HfB₂

Abstract

A comprehensive ab initio analysis of the ultra high temperature ceramics ZrB 2 and HfB 2 is presented. Density functional theory (DFT) computations were performed for the electronic, mechanical, thermal, and point defect properties of these materials. Lattice constants and elastic constants were determined. Computations of the electronic density of states, band structure, electron localization function, etc. show the diverse bonding types that exist in these materials. They also suggest the connection between the electronic structure and the superior mechanical properties. Lattice dynamical effects were considered, including phonon dispersions, vibrational densities of states, and specific heat curves. Point defect (vacancies and antisites) structures and energetics are also presented. W.-Y. Ching-contributing editor Manuscript No. 29044.

Electronic structure, phonon spectra and electron–phonon interaction in ScB2

“…Quite a number of theoretical studies of the electronic properties of the diborides are known to date [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Ivanovskii et al [9] performed full potential linear muffin-tin orbital (FP-LMTO) calculations of all hexagonal diborides of 3d (Sc, Ti, ..., Fe), 4d (Y, Zr, ..., Ru), and 5d (La, Hf, ..., Os) metals and analyzed the variations in their chemical stability and some other properties (e.g., melting temperatures, enthalpies of formation).…”

Interaction between Electron and Phonon Subsystems in Hafnium Diboride

“…So, author compares his results with theoretically calculated phonon DOS by Deligoz et al [12] and Lawson et al [10] (see Fig. 1 and Table).…”

“…VASP, the supercell method, based on the projected augmented wave potentials. Second method, ABINIT, uses Fritz Haber Insti- [10] is slightly closer to our calculation with respect to ABINIT data. There is a good agreement between author's calculations and the results of Deligoz et al [12] in a shape and energy position of the second peak in the phonon DOS.…”

“…This method is inconvenient for calculating phonon spectra for small qpoints as well as for compounds with large number of atoms per unit cell. Lawson et al [10] used two different codes to calculate the phonon spectra. VASP, the supercell method, based on the projected augmented wave potentials.…”

“…Lawson et al [10] studies the electronic structure and lattice properties of HfB 2 in a frame of the density functional theory (DFT). Lattice constants and elastic constants are determined.…”