Sodium Bismuth Titanate Based Lead-free Piezoelectric Ceramics The Doping Modification,

In recent years, people have begun to attach importance to the protection of ecological environment, in particular the requirements of sustainable development is proposed, people pay more attention to how to reduce the various forms of pollution. However, on the market, the piezoelectric elements in electronic devices are often made from lead-based piezoelectric ceramic material which has a certain degree of pollution of the environment we live. In order to reduce the pollution, the development of a good performance, less polluting lead-free piezoelectric ceramics will be particularly important.There are a lot of lead-free piezoelectric ceramic systems, this paper focused on the Bi0.5Na0.5TiO3system, and studied the performance of (Bi0.5Na0.5)0.94Ba0.06TiO3(BNBT6) with different doping capacity of Sr and Mn. The article outlines the piezoelectric material has both positive and reverse piezoelectric effect, and the necessary conditions of this effect., then briefly introduced the practical significance to study the lead-free piezoelectric ceramics as well as domestic and foreign research situation. After that, the process of mading ceramic materials by solid phase method is discussed as well as all aspects of the parameter settings and the characterization of the structure of the ceramic material. At last, the BNT experimental process and its performance test was analyzed.Pure BNT system materials (such as:the coercive field is relatively large, Ec=73kV/cm,making it the polarization becomes difficult) have many defects, so it is difficult to be practical, this requires the research of pure BNT system materials with different elements of doping and by using the relevant instruments for testing and analysis of material structure and properties, their performance is improved. This thesis was based on consideration of all aspects of the performance and characteristics of BNT ceramic materials, selected the solid-phase sintering process to study the impact of different doping of Sr and Mn on BNBT6. The specific programs are as follows, let X=0,0.02,0.04,0.06. Sr2+replaced Ba2+research different content of Sr2+replaced Ba2+in BNBT6of structure and performance of effect; respectively to0,0.1wt%/,0.3wt%,0.5wT%of MnO2-doped (Bi0.5Na0.5)0.94Ba0.06Ti03(BNBT6), study on the impact of MnO2content on properties of BNBT6. respectively Let X=0,0.02,0.04,0.06. Sr2+replaced Ba2+research different content of Sr2+replaced Ba2+on BNBT6of structure and performance of effect; respectively to0,0.1wt%,0.3wt%,0.5wT%of MnO2-doped (Bi0.5Na0.5)0.94Ba0.06TiO3(BNBT6), to study the impact of MnO2content on properties of BNBT6.In this experiment, the solid-phase sintering process is used to make the ceramic samples, in which the process parameters set as follows, samples calcined at850℃, holding time is120min, heating rate is2.5℃/min,; sintered at1150℃, holding time is120min, heating rate2.5℃/min.; burn Silver temperature of650℃, holding time120min, heating rate of2℃/min,; polarization process, temperature, voltage and time were set to60℃,3kv/mm,20min.(Bi0.5Na0.5)0.94Ba(0.06-x) SrxTiO3lead-free piezoelectric ceramic was achieved by solid phase method and the impact of different amounts of Sr2+instead of Ba2+on the microstructure, dielectric loss and electrical properties of (Bio.sNao.s)0.94Ba(0.06-x) SrxTiO3,(x=0.02,0.04,0.06) summarized as follows, XRD analysis shows that Sr2+have been instead of Ba2+into the BNBT6lattice (diffraction on phase-noise-free). SEM analysis shows that in the sintering temperature of1150℃, pure BNBT6over burning, when a small amount of Sr2+replaced Ba2+and found that the grain size becomes smaller, dense surface, this indicate that a small amount of strontium ions replace the barium ion can increase the density of the ceramics.When x=0.04,(Bi0.5Na0.5)0.94Ba(0.06-x) SrxTi03correlation between ceramic samples of the best, and piezoelectric properties of d33=118pC/N, Kp=0.20mechanical coupling coefficient, lowest dielectric losses tg8=0.026. when x>0.04,(Bi0.5Na0.5)0.94Ba(0.06-x)SrxTi03correlation of ceramic samples into a downward trend, dielectric loss increment.Using solid-phase preparation BNBT6+X (wt%), MnO2(x=0,0.1,0.3,0.5) lead-free piezoelectric ceramics. The impact of different content of MnO2ceramics doped with different density, piezoelectric and dielectric loss coefficient, mechanical coupling coefficient of effect, summarized as follows,:When mixed with a small amount of manganese in BNBT6, ceramic will became tight, and pressure electric performance has rose, and between electric loss reduced;when doping volume for0.3wt%, all area performance best, pressure electric performance d33=120pC/N, machinery coupled coefficient Kp=0.27, between electric loss minimum tgδ=0.020; But when x>0.3wt%, ceramic of tight of and performance are has reduced, between electric loss is rising. These two experiments show that a small amount of dopant can improve the performance of BNBT6, but too much, it will affect the density of ceramic, thereby reduc the performance of ceramic, also increased its loss.