Strong pressure dependence of the valence band maximum in tetragonal ZrO2

ZrO2 is a semiconductor compound widely used in several areas such as part of electronic devices, energy related materials, and catalysis due to its attractive electronic characteristics. In this work we explore its electronic properties in the surroundings of the energy gap. In particular, we show that the valence band maximum (VBM) could be strongly modulated with pressure. Using the Generalized Gradient Approximation within the Density Functional Theory we find that under compression the VBM moves, in reciprocal space, from a non-special point T-Sigma = ( tau , tau , 0), with tau approximate to 0.23 in equilibrium, to A = (1/2, 1/2, 1/2) then to N V which moves with increasing pressure in the A -> M line, and finally to M = (1/2, 1/2, 0). These transitions are studied by providing an approximation to the carrier effective mass components at the VBM and their variations with pressure, as well as the variations of the band gap. Since ZrO2 is very often used in situations under stress, this effect could strongly influence the evolution of the band gap, the electronic conductivity, and therefore could also be important for certain applications in electronics and catalysis.