温度对无铅换能器陶瓷BNT-7BT铁电性的影响

Effect of Temperature on the Ferroelectricity of Lead-free Transducer Ceramics BNT-7BT

传统换能器材料——PZT95/5铁电陶瓷中的铅元素对环境污染大,且其电致应变(S)和压电系数(d33)较小,因此限制了换能器的输出功率。该文从保护环境和优化换能器性能的角度出发,研制出位于准同型相界处的无铅铁电陶瓷0.93Bi_(0.5)Na_(0.5)TiO_3-0.07BaTiO_3(BNT-7BT),测试了其晶体结构和介电温谱曲线,并得到了温度对该陶瓷电滞回线及电致应变曲线的影响。实验结果表明,钙钛矿结构的无铅铁电陶瓷BNT-7BT在152℃处发生铁电→反铁电相变,且其具有较大的电致应变量(室温下S≈2.92‰)和较高的压电系数(d33=152pC/N)。

The lead elements in the conventional PZT95/5ferroelectric ceramic material for transducer have great pollution to the environment,and its electrostrictive strain Sand piezoelectric constant d33 are small,the output power of transducer is limited.From the perspective of protecting environment and improving the performance of transducers,we have prepared lead-free ferroelectric ceramics 0.93Bi_(0.5)Na_(0.5)TiO_3-0.07BaTiO_3(BNT-7BT)which located in the morphotropic phase boundary(MPB).The crystal structure and dielectric temperature curve have been tested.The effect of temperature on its hysteresis loops and electrostrictive-strain loops have already been investigated.The results indicate that the ferroelectric to antiferroelectric phase transition of the prepared lead-free ferroelectric ceramics BNT-7BT with perovskite structure occurs at 152℃.In addition,the BNT-7BT has large electrostrictive strain(S≈2.92‰ at room temperature)and high piezoelectric constants(d33=152pC/N).