Research On Preparation And Properties Of BCTZ Lead-free Plezoelectric Ceramics

The research and application of Barium Titanate (BaTiO3) based piezoelectric ceramic material has been very mature at present, and the related materials are widely used in the fields of light, sound, electronics and so on. In recent decades, these materials have attracted considerable attention as a kind of excellent ferroelectric materials. Nevertheless, the low Curie temperature (Tc=120℃) and poor stability of temperature had limited their application at room temperature.The BCZT ceramic, as a new kind of binary-system ceramic materials, showed very high piezoelectric performances around morphotropic phase boundary (MPB), the numerical value of d33 can reach to 600 pC/N, which can be comparable with piezoelectric performances of lead-based ceramics materials.But, a series of disappointing disadvantage still exist in the material and limit its broader application.In this paper, a series of BZT-BCT lead-free piezoelectric ceramics were prepared using solid phase technique. The aim is to find out the most excellent composition of ferroelectric, dielectric and piezoelectric performances from different compositions of BZT-BCT ceramics through different analysis and comparison of the performance of BZT-BCT ceramics. Furthermore, in terms of the optimal composition ceramic, firstly, study is conducted on optimal composition ceramic microstructure, morphology and the relationship of the electrical performances and the sintering temperature at different sintering temperatures; secondly, in the preferred sintering temperature, influence to optimal composition ceramic electric hysteresis loops and polarization switching current caused by of the electric field, frequency and temperature is researched, analyzing ceramic polarization switching process of the optimal composition.XRD test results of BZT-BCT ceramics of different compositions show that all samples prepared at a sintering temperature of 1400～1500℃ have typical perovskite structure, suggesting that Ca and Zr diffuse into the BaTiO3 lattice to form a solid solution; at room temperature, BZT-BCT ceramics appeared the coexistence of the orthorhombic phase.Electric performances test on BZT-BCT ceramics of different compositions show that the piezoelectric performances of the eight ceramic are at the best level, which is because morphortropic phase boundary is most easily approached, so come its most excellent electric performances, thus further verify the morphotropic phase boundary theory. And the d33 value of the maximum piezoelectric coefficient can reach to 384.4pC/N.These studies have shown that different compositions BCZT ceramics,sintered at different temperatures (1400～1500℃),all the BCZT ceramics have a typical perovskite structure, and at different sintering temperature coexistence state of rhombohedral and tetragonal phase exists in BCZT ceramics; when the sintering temperature is 1450℃,The eight ceramics BCZT possess excellent electric performances.