Study On BaTiO₃-BiFeO₃ Piezoelectric Material

With the researches into piezoelectric materials in recent years, the lead-free piezoelectric material, due to its environmental friendliness and increasingly prominent performance, has been gradually replaced the position of lead piezoelectric materials in practical application. BaTiO3-BiFeO3 ceramic material is a system material that has a high piezoelectric coefficient and high Curie temperature. This article describes the development history of the piezoelectric materials, and researches into the formulation and processes of BaTiO3-BiFeO3 ceramics materials.First, the article researches on the sintering temperature and composition of xBaTiO3-(1-x)BiFeO3 ceramics. Researches show that too low sintering temperature is not conducive to the growth of grains, while too high temperature will destroy the crystal structure. In the xBa TiO3-(1-x)BiFeO3 system, along with the increasing of BaTiO3 component, losses of the xBaTiO3-(1-x)BiFeO3 materials decrease and the density increases. 0.3BT-0.7BF has the optimum properties when sintered at 1050℃.Secondly, this article researches on the optimum polarizing temperature and polarizing voltage of BaTiO3-BiFeO3 materials. The result shows that BaTiO3-BiFeO3 materials have the optimum piezoelectric property(e.g. d33 constant of 209pC/N) under the polarizing temperature of 125℃ and the polarizing voltage of 2.5kv.Thirdly, this article researches into the affects of Mg-doping and Mn-doping on the microstructure and piezoelectric property of BaTiO3-BiFeO3 materials respectively. The results show that with the increasing of Mg content, the sintering temperature of BaTiO3-BiFeO3 materials declines and losses decrease as well. Mg-doping has changed the original unstable state of the crystal. The piezoelectric coefficient of 0.20BT-0.70BF-0.10 MgO could reach 249pC/N after polarization. Mn, as a sintering aid, has promoted the density and grain growth of ceramics. With the increasing of Mn-doping, the density of the crystal increases, the crystal cell becomes smaller, and the porosity becomes smaller. The piezoelectric coefficient(i.e. d33) of 0.20BT-0.70BF-MnO reaches 253pC/N.Finally, this article researches into the affects of Mg&Mn co-doping on the microstructure and piezoelectric properties of BaTiO3-BiFeO3 materials. The results show that co-doping has greatly improved the stability and density of the crystal, making the piezoelectric property of the crystal in a relatively stable state. Mn-doping has made the original referral situation changed due to the different valences of Mn. As the radius of Mg ion is smaller than that of Ba ion, the A-substitution occurs, improving the original electrical property. After co-doping, the crystal loss decreases and crystal state becomes stable. The piezoelectric coefficient(i.e. d33) of 0.20BT-0.10MgO-0.70BF-MnO reaches 343pC/N.