Structure Design And Property Optimization Of BCZT Lead-Free Piezoelectric Ceramics

In2009, professor Ren Xiaobing found that the zirconium barium titanate calcium (BCZT) lead-free piezoelectric ceramics have excellent properties which could even comparable with PbTiO3based ceramics and attract lots of attention. In this thesis, researchers were focused on (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3(BCZT) lead-free piezoelectric ceramics, which showed excellent electric properties and have not been under research for every long time. Our researches were consisted of the ceramics preparation process, zirconium/titanium ratio and barium/calcium ratio on the material properties. The main of this paper contents are as follows:Chapter one is the introduction. Firstly, the fundamental of ferroelectrics, their important parameters and their classification were briefly introduced. Then, the present status of lead-free piezoelectric ceramics was reviewed. Lastly, the contents of the dissertation were presented.Chapter two is the details of experimental procedure. Firstly, detailed the procedure of sample preparation. Then, design the appropriate characterization techniques to assessment the properties of the samples. The instruments which have been used in the experiment were briefly introduced.Chapter three presents mainly that the effect of sample preparation technology to the properties. Based on early experience, the sintering temperature was set at1540℃. The samples were sintering for different dwelling time, set for different property tests. Then compared with each other for their properties. The grain size of the samples which sintering for different dwelling time are different from each other, which influence the performance optimization. The tests of density, dielectric properties and ferroelectric properties etc were taken too.Chapter four studies the influence of Zr/Ti ratio adjustment on the performance of (Bao.85Ca0.15)(ZrxTi1-x)03lead-free piezoelectric ceramics. The x value is between0.00and0.20, selected five points. The Curie temperature Tc became lower, and the dielectric constant of the textured (Ba0.85Ca0.15)(ZrxTi1-x)03ceramics becomes higher, with the Zr content increases. When x=0.10, the piezoelectric property reaches the maximum value, the sample got best piezoelectric property.Chapter five studies the influence of Ba/Ca ratio adjustment on the performance of (Ba1-xCax)(Zr0.1Ti0.9)03lead-free piezoelectric ceramics. The experiment method is just like the chapter before. The x value is between0.05and0.25, selected five points. The grain size gets smaller and the Curie temperature Tc shifts to the lower temperature with the Ca content increases. When x=0.15, the piezoelectric property reaches the maximum value, the sample got best piezoelectric property.Chapter six summarizes the main results and innovations in the dissertation, and the perspective of the piezoelectric material is also addressed.