Structure And Electrical Properties Of Pb0.925Ba0.075Nb2O6 High Temperature Piezoelectric Ceramics

The high temperature piezoelectric ceramics materials can be applied into high temperature piezoelectric devices only when it has no phase transition which affects the piezoelectric properties of the materials in higher temperature. In this paper, the PbNb2O6-based piezoelectric ceramics were studied by adopting B2O3 and two step sintering process. The Pb0.925Ba0.075Nb2O6-0.5wt%TiO2-xwt%B2O3(PBNT-xB) (0<x<0.08), Pb0.925Ba0.075Nb206-0.5wt%Ti02ceramics were prepared via a conventional solid state reaction method and studied in terms of their microstructure, dielectric and piezoelectric properties. The obtained results are as following:(1) A series of Pb0.925Ba0.075Nb206-0.5wt%TiO2-xwt%B203(PBNT-xB) (0≤x≤0.08) were prepared via a conventional solid state reaction method. Crystallite structure was investigated using X-ray diffraction (XRD), and microstructure of the ceramics was observed using scanning electron microscope (SEM). The studies have showed that all PBNT-xB ceramics exhibit a single orthorhombic phase in the range of 1250～1280℃, and the optimum amount of B2O3 additives can improve the density and the electrical properties of ceramics. With the optimum component x=0.04, the ceramics have the excellent electrical properties:d33=85 pC/N, Qm=22.37, tanδ=0.0101, Tc=524℃, and the value of piezoelectric coefficient d33 is stable when the temperature is 500℃.(2) The microstructure, dielectric and piezoelectric properties of the Pb0.925Ba0.075Nb2O6-0.5wt%Ti02 ceramics were studied via two step sintering process(TTS). The X-ray diffraction showed that PBNT ceramics exhibit a single orthorhombic phase after sintering at high temperature 1280 ℃, and low temperature 1140℃ for 4 h, which greatly reduces the sintering temperature. SEM showed that the relative density is improved, Dr=96.8%, and the grain size is decreased. The optimum temperature with high temperature 1280 ℃, and low temperature of 1140℃ C for 4 h possesses the excellent electrical properties:Dr=96.4%,d33=84 pC/N, Qm=23.28, tanδ=0.0069, Tc=531℃。(3) A series of Pb0.92sBa0.07sNb2O6-xwt%TiO2 ceramics (Φ=30 mm, thickness=3 mm)were prepared via a conventional solid state reaction method, in addition, the repetitiveness of Pb0.92sBa0.075Nb2O6-xwt%TiO2 ceramics are studied on sintering temperature, sintering time temperature and doping B2O3.The results show that the ceramics sintered at 1270℃ for 4 h possesses the excellent electrical properties:d33=83 pC/N, however, the repetitiveness is difficult to improve. Adding B2O3 can improve the repetitiveness of the ceramics, but decrease the piezoelectric constant. The optimum component with x= 0.06 sintered at 1260℃ for 4 h possesses the excellent electrical properties:d33=68 pC/N.