The influences of lattice distortion on the antiferroelectric transition and relaxation of oxygen vacancies in high-entropy perovskites (Bi0.2Na0.2Ba0.2K0.2X0.2)TiO3 with X=Ca, Sr or La

Abstract

High entropy ceramics (HECs) (Bi0.2Na0.2Ba0.2K0.2X0.2)TiO3, X=Ca, Sr or La, with a perovskite structure have been successfully synthesized using a modified citrate acid method. Lattice distortion is a main feature of the HECs which significantly influences their antiferroelectric phase transition behaviors. It is shown that the activation energy of oxygen-vacancy relaxation could quantitatively reflect the lattice distortion of perovskite HECs, as characterized by X-ray diffraction, dynamical mechanical analysis and Raman spectroscopy. Based on the activation energy, the lattice-distortion driven antiferroelectric transition in HECs can be also characterized, providing a viable strategy to design the structural, dielectric and ferroelectric properties as finely tuned by chemical disorder at A or B site in perovskite HECs.