Preparation And Properties Of BMT - PT High Temperature Piezoelectric Ceramics

At present, piezoelectric ceramics have been widely used in communication, aerospace, detection and computer, etc. However, with the rapid development of science and technology, there are number of piezoelectric sensors and devices, such as aerospace, geological survey, automotive industry, which have expressed the need above200℃for piezoelectric materials. Generall, inorder to ensure the stability of the piezoelectric properties, the operating temperature of most commercial piezoelectric ceramic is limited to half of the Curie temperature, about150℃, restricting the application in high temperature field. In2004, new high temperature ferroelectric materials based on (1-x)Bi(Mg1/2Ti1/2)O3-xPbTiO3(BMT-xPT) solid solutions have been found, which was a new page for study on high Curie temperature and high-performance bismuth based perovskite piezoelectric ceramics.In this paper, BMT-PT ceramics were prepared by conventional solid state reaction method. The structure, sintering behavior, microstructure, dielectric and ferroelectric properties of ceramics with adding PbTiO3were studied respectively. Finally, the BMT-PT ceramic system for the modification of doping.(1) BMT-xPT ceramic were prepared by conventional solid state reaction method. XRD diffraction results show that the sample components are pure perovskite structure, and no secondary phase. The fitting results show that, with the PT content increasing from x=0.36to x=0.40, a phase transition from the coexistence of rhombohedarl and tetragonal phases to tetragonal phases was observed. In the dielectric spectrum curve, all components are two distinct dielectric peaks, one at400℃, another600℃. With the increase of the test frequency, the first dielectric peaks shift to high temperature, as PT content increasing; second dielectric peak decreases with the PT content increasing. Seen from the P-E curve of the ceramic samples, the PT content affects the ferroelectric properties of the material. The x=0.42, has the largest saturation polarization Pm=19.1μC/cm2and the piezoelectric constant d33=218pC/N.(2)0.63BMT-0.37PT-xBFO(x=0.0mol%,1.5mol%,4.5mol%,7.5mol%) were prepared by solid state reaction method. The ceramics were sintered at1075℃. The phase structure and electronic properties of components were discussed. X-ray diffraction results show that the rhombohedral and tetragonal co-existed in all the samples. SEM shows that the addition of BFO promotes the ceramic grain growth. The dielectric property indicates that all the samples are relaxation ferroelectric (y close to2), which can ameliorate the dielectric temperature stability of materials. For x=0.015sample, it exhibited high saturation polarization and remnant polarization,38μC/cm2and29μC/cm2.