Quantitative Description of the Diffuse Phase Transition of BNT-NKN Ceramics

Abstract

A perovskite solid solution of (1-x)(Bi_0.5Na_0.5)TiO₃-x(Na_0.5K_0.5)NbO₃ (BNT-xNKN) (x = 0–0.08) synthesized by solid state reaction technique exhibits diffuse phase transition (DPT) behavior. Power law, Gauss-type quadratic law and Lorenz-type quadratic law was employed to characterize the dielectric permittivity peaks near T_m . The diffuseness parameters γ, δ_G and δ_A increase with the increase in the value of x, which implies a composition-induced diffuse transition. Among these laws simulating dielectric response in diffusion ferroelectric phase transition, the Lorenz-type quadratic law is the best to describe the characterization of DPT behavior in such a wide temperature range as observed in our experiment.

Keywords:

• Perovskite
• ceramics
• phase transition
• diffuseness parameters

Acknowledgments

This work was financially supported by Natural Science Foundation of China (Grant Nos. 51002036, 21061004, and 50962004), by the Natural Science Foundation of Guangxi (Grant Nos. BA053007 and C013002) and the Projects of the Department of Science and Technology of Guangxi (Grant Nos. 12118017-13, 0842003, and 09-007-02).