采用固相法制备了Mn改性的CaBi4Ti4O15(CBT+xmol%MnCO3)层状压电陶瓷.介电温谱显示所有样品居里点在780℃附近,并且发现该材料在110K处有一介电弛豫峰.Mn的加入显著降低了高温下的介电损耗,剩余极化轻微降低,室温介电常数从173减小到162,同时机械品质因子由2700增加到4400,显示了硬性掺杂的效果.在100~600℃范围内,x=1.0的样品比纯组分的电阻率提高了一个数量级以上,500℃的电阻率提高了约2个数量级(10^8Ω·cm),电阻率对温度的Arrhenius拟合由两段过渡到三段,压电系数d33由7提高到14.5.实验结果表明,Mn改性的CBT在高温传感器等领域具有应用前景.
Mn-modified CaBi4Ti4O15 (CBT+x mol% MnCO3) layer-structured piezoelectric ceramics were prepared by the solid state reaction technology. All samples have the same Curie temperature of 780℃, but the dielectric loss at high temperature is remarkably lowered by Mn addition. With increasing content of Mn, the remnant polarization is slightly decreased; the dielectric constant at room temperature decreases from 173 to 162; and the mechanical quality factor increases from 2700 to 4400. The piezoelectric constant d33 is enhanced from 7 to 14.5. The resistivity of 1.0mol% Mn modified sample is found to be 10^8Ω·cm at 500℃, 50 times higher than that of pure CBT. The Arrehenius plot of Mn-modified CBT is fitted by 3 straight lines, while that of pure CBT is fitted by 2 straight lines. The results suggest that the Mn modified CBT is a potential material for high temperature sensing application.