Pressure-induced phase transition of KTa1/2Nb1/2O3 solid solutions: A first-principles study

Highlights: • Structures and electronic properties of KTa_1/2Nb_1/2O₃ under high pressures. • Prediction of stable high pressure phases with the pressure range of KTa_1/2Nb_1/2O₃. • Indirect band-gap semiconductors of KTN[1 0 0] and KTN[1 1 0]. The structures and electronic properties of KTa_1/2Nb_1/2O₃ under high pressures have been investigated using the first-principles calculations. Three candidates with B site cation ordered along the [1 0 0], [1 1 0] and [1 1 1] directions are found stable under different pressures by thermodynamics, mechanics and dynamics stability criteria. Further electronic analysis indicates that three structures are semiconductors with different band-gap characteristics. The peculiar chemical bonds of Nb-O and Ta-O are expected to be related to the different electronegativity of the corresponding cations.