The microscopic mechanism in the realization of ultra-wide temperature range stability in Bi3+,Na+,Zn2+,Nb5+ doped BaTiO3 dielectric system

Abstract

A novel lead-free, ultra-wide temperature range stable dielectric ceramic with a high dielectric constant was prepared by a traditional solid-state reaction method. The microscopic mechanism, and the electric and dielectric properties of the Bi³⁺,Na⁺,Zn²⁺,Nb⁵⁺ doped BaTiO₃ dielectric system were investigated for the first time. X-ray diffraction revealed that Bi³⁺,Na⁺,Zn²⁺,Nb⁵⁺ and BaTiO₃ form a solid-solution with a pseudo-cubic structure. The thermal vibration and interactions between the dipoles contributing to the realization of an ultra-wide temperature range stability, were discussed. The microscopic model based on the bond energy and coordination number, was used to research the changes of the dielectric stability. In this paper, the relationship between microscopic mechanism and the macroscopic dielectric properties in the ultra-wide temperature range stable dielectric ceramics was established, thereby paving the way for achieving ultra-wide temperature range capacitors. In addition, fine dielectric properties of (Na_0.015Bi_0.3Ba_0.685)(Zn_0.2Nb_0.115Ti_0.685)O₃ with an ε_r of 700, and tan δ of 0.00535 can be obtained over an ultra-wide temperature range (−53 to 350 °C). These features give the ceramic system high practical value in miniaturization and increasing applications in harsh environments.