Sm掺杂PMN–PT弛豫铁电陶瓷的大信号径向谐振响应

Large Signal Radial Resonant Responses of Sm-Doped PMN-PT Relaxor Ferroelectric Ceramics

弛豫铁电材料因具有高的介电常数和压电系数而广泛应用于致动器、换能器等领域。实际使用中往往需要施加大信号激励驱动谐振,因此了解掌握大信号激励下的谐振特性变化极为重要。然而,目前这方面的研究却少有文献报道。针对这一问题,以二步氧化物固相反应法制备了高压电性Pb_(0.9625)Sm_(0.025)[(Mg_(1/3)Nb_(2/3))0.71Ti_(0.29)]O_(3)陶瓷材料,用本人搭建的大信号谐振响应测试系统研究了驱动场幅值和温度对径向谐振特性的影响。结果表明:低驱动场下谐振响应能保持单一谐振峰直至完全退极化,但随着驱动场的增大谐振响应变得复杂,即使在低温也呈现多个谐振峰。谐振特性的变化与机械品质因子Qm、铁电宏畴尺寸及相组成密切相关,低Qm材料在大驱动场下产生的内热加速了宏畴裂解并引发了二级铁电相变。谐振特性的不稳定及较大谐振频率温度系数限制了Sm改性PMN–PT弛豫铁电陶瓷的应用,尤其是在大信号下。

Pb_(0.9625)Sm_(0.025)[(Mg_(1/3)Nb_(2/3))0.71Ti_(0.29)]O_(3) ceramic material with a high piezoelectricity wasprepared by a two-step oxide solid reaction method.The effects of driving field amplitude and temperature on the radial resonance characteristics were investigatedby a large signal resonant response test system.The results show that the resonant response at a low driving field can maintain a single resonant peak until complete depolarization.However,the resonant response becomes complicated,and some multiple resonant peaks appear even at a low temperatureas a driving field increases.The resonant properties areclosely related to the mechanical quality factor Om,ferroelectric domain size and phase composition.The thermal effect produced by applying a high driving field on the low Om material accelerates the splitting of macro-domains and induces a first-order ferroelectric phase transition.The instability of resonant characteristics and the large resonant frequency temperature coefficient restrictthe application of Sm-doped PMN-PTrelaxor ferroelectric ceramics,especially at a high driving field.