First-principles investigations of the crystal and electronic structures, dynamical and mechanical stabilities, Born effective charges and dielectric permittivities of a novel tetragonal zirconia

Abstract

In this paper, a novel tetragonal ZrO2 phase has been predicted from first-principles calculations. The detailed crystal structural analysis shows that the tetragonal ZrO2 has a space group I41/amd (D4h19, No. 141) with 4 formula units per unit cell and 16 symmetry operations as well as six-fold cation coordination. The Zr atoms occupy 4a Wyckoff positions (0, 1/2, 1/4) and (1/2, 1/2, 1/2) and the O atoms occupy 8e Wyckoff positions (0, 0, z+1/8), (0, 1/2, z+3/8), (1/2, 0, -z+5/8) and (1/2, 1/2, -z+3/8) with z = 0.0761. The electronic structures, dynamical and mechanical stabilities investigations show the tetragonal ZrO2 is dynamical and mechanical stable as well as with a large direct band gap of 3.9015eV at Γ point. The phonon dispersion is divided into two regions: the low frequency part (0–8.6240 THz) and the high frequency part (10.3453–18.4034 THz) with a separation gap of 1.7213 THz. The magnitudes of Born effective charges are greater than the nominal chemical valences of +4 and −2 for Zr and O ions, respectively, reflecting a strong dynamic charge transfer from Zr to O atoms and thus a p-d hybridized Zr–O ionic bond. A diagonal and anisotropic static dielectric permittivity εij0 is obtained between ab-plane ε110=ε220=17.80 and along c axis ε330=14.77.