A Theoretical Study on the Pressure-Induced Phase Transitions in the Inverse Spinel Structure Zn2SnO4

The structural and electronic properties of Zn2SnO4 under high pressure have been investigated using the density functional formalism under the nonlocal B3LYP approximation. We have determined its stability against decomposition to ZnO and SnO2 mixture as well as toward recently observed orthorhombic phases, similar to CaTi2O4 (titanite-type) CaFe2O4 (ferrite-type) and Sr2PbO4 structures. Numerical and analytical fittings have been carried out to determine the equilibrium unit cell geometry and equation of state parameters for all the structures and compounds involved in the phase diagram. The pressure dependences of band structures, energy gap, and density of states are also investigated. For inverse and titanate-type structures, the vibrational frequencies and their pressure dependence have been calculated. A microscopic analysis in terms of polyhedral and bond compressibilities leads to identify the ionic displacements accompanying the phase transformations and to an appealing interpretation of the phase response to compression. The present results provide a deeper insight into the relative stability, structural, electronic, and vibrational properties of the different phases.