Structure Design And Property Modulation On Barium Titanate Based Lead-free Piezoelectric Materials

The zirconium barium titanate calcium (Ba,Ca)(Ti,Zr)O3lead-free piezoelectric ceramics have excellent properties comparable with that of PbTiO3based ceramics and attract lots of attention. In this thesis, researchers were focused on (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3(BCTZ) ceramics, which showed excellent electric properties and is not under research for long. Our researches were consisted of the ceramics preparation process and zirconium/titanium ratio on the material properties. Main contents of the thesis are the influences of raw materials, sintering temperature and dwelling times to the properties of BCTZ, the influence of Zr/Ti ratio adjustment on the performance of (Ba0.85Ca0.15)(Ti1-xZrx)O3ceramics.The results from the influences of raw materials, sintering temperature and dwelling times to the properties of BCTZ are as follows. The piezoelectric property using P25as raw material is better than using SCRC as raw material, visibly particle size and purity of the raw materials influence ceramic density and then affect the properties of ceramics. The grain size is dominated by sintering temperature, which influence the performance optimization. The piezoelectric property reaches largest at the sintering temperature1540℃, also we found the dielectric loss relaxation phenomenon and the dispersion phenomenon near the Curie temperature. Through the experiment, the dielectric relaxation related to the oxygen vacancy. The dielectric relaxation parameters, dispersion phenomenon and dynamics are discussed in this paper.The results from the influence of Zr/Ti ratio adjustment on the performance of (Ba0.85Ca0.15)(Ti1-xZrx)O3ceramics are as follows. The Curie temperature Tc shifts to the lower temperature, and the dielectric constant of the textured (Ba0.85Ca0.15)(Ti1-xZrx)O3ceramics becomes higher, with the Zr content increases. The piezoelectric property reaches the largest at x=0.10. At the same time, the relaxation phenomenon was found on the textured samples. The study of the dielectric properties with the changes of bias voltage found the new C-V curve, and the dielectric permittivity can be modulated by the zirconium element doping. Stress-strain performance gets maximum0.56%at x=0.10, even comparable with the lead base ceramics.