钛酸锶钡的力致相变机理及力电耦合性能

Stress-induced Phase Transitions and Electromechanical Coupling Properties in Barium Strontium Titanate

钛酸锶钡作为一种典型的无铅铁电材料,受到了越来越多的关注,但提高室温钛酸锶钡的力电耦合性能是其应用的关键.基于热力学唯象理论,研究了Ba0.75Sr0.25TiO3铁电材料的力致相变行为,及相变过程中的力电性能.结果表明,Ba0.75Sr0.25TiO3在应力诱导下发生了铁电相变,相变过程中极化、应变、介电常数、压电系数均发生突变,较好地解释了实验中观测到的铁电材料应力-极化、应力-应变非线性现象.结果表明,力致相变能够增强铁电材料力电耦合性能,这为实验制备高性能无铅铁电材料提供了指引.

As a typical lead-free ferroelectric material,barium strontium titanate has received more and more attention,while the enhancement of its electromechanical coupling properties at room temperature is important.Based on thermodynamic phenomenological theory,we studied the stress-induced phase transitions and electromechanical coupling properties of barium strontium titanate crystals.The results show that Ba 0.75 Sr 0.25 TiO3 undergoes phase transformation under stress,and the corresponding polarization,strain,dielectric constants and piezoelectric coefficients show anomalous responses.The general trend agrees well with experimental observations.The results also suggest that stress-induced phase transition can enhance the electromechanical coupling properties of ferroelectric materials,which offers a guideline for experiments.