Structures and elastic properties of paraelectric and ferroelectric KTa0.5Nb0.5O3 from first-principles calculation

The structures, elastic properties and intrinsic hardness of B–O bonds of KTa0.5Nb0.5O3 crystal in paraelectric and ferroelectric phase structures have been investigated by means of the density functional theory. Both structures are found to be elastically stable and in good agreement with available results. The elastic properties including the bulk modulus, shear modulus and Young’s modulus change largely during phase transition. The paraelectric KTa0.5Nb0.5O3 crystal is more incompressible and harder than ferroelectric phase. The hardness of KTa0.5Nb0.5O3 crystal is mostly determined by Nb–O bonds and the modifications of the bond strength affect the hardness of the crystal. Charge density contours indicate that the electronic distributions between B–O bonds play an important role in the formation of elastic properties.

Research highlights
► We investigated the paraelectric/ferroelectric KTa0.5Nb0.5O3 crystal by the density functional theory.
► We calculated the structure, elastic properties and intrinsic hardness of the B–O bond.
► We compare bulk modulus, shear modulus, Young’s modulus and the intrinsic hardness for two phases.
► The electronic distributions of B–O bonds affect elastic change during phase transition.