Dissertation > Industrial Technology > Electrotechnical > Electrical materials > Electric and ceramic materials > Piezoelectric ceramics

Preparation and Performance Adjustment of Bisco3-pbtio3Based High Temperature Piezoelectric Ceramics

Author QianWangJie
Tutor YangYing; WangYiPing
School Nanjing University of Aeronautics and Astronautics
Course Materials Processing Engineering
Keywords Piezoelectric ceramics BS-PT Mechanical quality factor The Curie temperature Thermal stability PYN
Type Master's thesis
Year 2012
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Nowadays, high-temperature piezoelectric materials have received a great deal of attentionbecause the automotive industry, the energy industry and the aerospace industry have urgent demandsof sensors and actuators that can work at high temperature. Bi-based perovskite solid solution systemBiScO3-PbTiO3(BS-PT) exhibits promising high-temperature applications because of its largepiezoelectric coefficient (d33=450pC/N) and high Curie temperature (Tc=450°C) in the vicinity ofmorphotropic phase boundary (MPB). However, there are also several shortcomings of BS-PTincluding low value of the mechanical quality factor (Qm), high cost of Sc2O3and so on. Based onBS-PT binary system, PMS and PYN were selected as the third end members to form novel ternarysystems with BS-PT. The phases, microstructure and electric properties at room temperature and hightemperature of the ternary systems0.07Pb(Mn1/3Sb2/3)O3-(0.93-x)BiScO3-xPbTiO3(PMS-BS-xPT)and (0.92-x)BiScO3-xPbTiO3-0.08Pb(Yb1/2Nb1/2)O3(BS-xPT-PYN) were systematically studied inthis thesis work.PMS-BS-xPT (x=0.520.72) ceramics were synthesized by conventional solid-state method. Theeffect of PMS and different BS/PT ratio on the properties of ceramics was studied. The results vertifythat the MPB region lies in x=0.6, the ceramics of this composition possess good properties: εr=993,d33=225pC/N, kp=0.38. The Tcof the ceramics changed significantly with varying of PT content, at thesame time a remarkable frequency dispersion behavior was observed. The doping of PMS improvesthe “hard” piezoelectric characteristics of the ceramics. The Qmreaches1291when x=0.72while thedielectric loss down to lower than1%when x≥0.6. The P-E loops of the ceramics presented a pinchedshape at low electric field because of the pinning effect induced by the PMS-doping.BS-xPT-PYN (x=0.540.62) ceramics was prepared by columbite precursor method. The MPBshifts slightly to x=0.560.58, when x=0.58the optimum properties were obtained: εr=1260, d33=370pC/N, kp=0.46, respectively. With the increase of PT, the tetragonality and Tmof ceramics increasecorrespondingly. The maximum dielectric permittivity of MPB composition reached27,000at thetemperature of Tm370°C. High-temperature performance tests show that PYN-doping makesmaterials better high temperature stability. Near MPB composition piezoelectric parameters includingkp, Qmand Prof the ceramics increase with temperature increasing and reaches their maxima at200°C and it can be ascribed to the enhanced extrinsic piezoelectric response. This temperature-propertybehavior of the material is completely different from the temperature dependence of electrical properties of traditional PZT ceramics. On the other hand the specimens retained their high resistivebehavior up to200°C. It is expected that PYN-doping BS-PT ceramics can be a promising candidatefor high-temperature piezoelectric applications.

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