Effects of W/Cr Co-doping on the Crystal Structure and Electric Properties of CaBi2Nb2O9 Piezoceramics
Calcium bismuth niobate(CaBi2Nb2O9)is a typical bismuth layered structure piezoelectric material with high Curie temperature(about 943℃)and high stability,which is an important candidate functional element for high temperature vibration sensors above 600℃.However,its low piezoelectric coefficient and high temperature resistivity seriously limit the signal acquisition of high-temperature piezoelectric vibration sensor.To improve the comprehensive performance,in this work,W/Cr co-doped CaBi2Nb1.975W0.025O9-x%Cr2O3(CBNW-x Cr,0<x≤0.2)Aurivillius phase ceramics were prepared via conventional solid-state sintering route.The effects of W/Cr co-doping on the crystal structure and electrical properties of CBN piezoelectric ceramics were investigated.The results show that co-doping of W/Cr elements transforms crystal structure of the ceramics from orthorhombic to tetragonal crystal system,enhances distortion of the crystal structure,and significantly improves piezoelectric and insulating properties of the piezoelectric ceramics.When x=0.1,the Curie temperature is 931℃,the piezoelectric coefficient is 15.6 pC/N,the resistivity reaches the order of 106 Ω·cm at 600℃,and the dielectric loss is only 0.029,which endows the system an important potential application in the field of high-temperature piezoelectricity.
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