Study Of The Preparation And Properties Of Pb_1-xCa_xZrO₃ Ceramics

In this thesis,Pb1-x CaxZrO3【abbreviated as PCZ(x)】ceramics were prepared by processing of solid oxide,Pechini and co-precipitation methods. By means of differential thermal analysis(DTA),the reaction temperature of PCZ(x) powers was decided,and on the basis of this, the process of preparing PCZ(x) ceramics was optimized. By means of modern analysis techniques, such as laser particle size analyzer, X-ray diffraction(XRD), scanning electron microscopy(SEM) etc,the particle size and distribution of power's diameter, crystallized properties, the microstructure of PCZ(x) ceramics were investigated and the structure of PCZ(x) poly-crystals were studied systemically. The dielectric properties of PCZ(x) ceramics were tested in different frequency. The main conclusions obtained from aboved-mentioned research works are as follows:The PCZ(x) ceramics prepared by the wet chemical synthesis methods were studied by DTA,which indicated that the sintered temperature of PCZ(x) ceramics only was about 1100℃.The PCZ(x) powers prepared by solid oxide, Pechini and co-precipitation methods were studied by laser particle size analyzer, which indicated that the average size of powers prepared by solid synthesis was 143nm , the average size of powers prepared by Pechini methods was 93nm and the average size of powers prepared by co-deposition methods was 62nm. So the average size of PCZ(x) powers prepared by co-deposition methods was least.The experiment results indicated that the complete perovskite structure is obtained when the sintering temperature is about 1200℃ of the PCZ(0.33)ceramic prepared by solid oxide. And the sintering temperature must be proper and not too high, because the over high temperature will cause the great loss of PbO, which will result in the impure phase in the PCZ(x) ceramics. The PCZ(0.35)ceramics prepared by Pechini method were studied by XRD, which indicated that the peaks of PCZ(x) ceramic moves rightward with the increasing of temperature, which means the distance between two crystal plane decreases with the increasing of temperature. The results indicated that the increasing of temperature is favor to complete reaction, and the decreasing of the distance between two crystal plane is caused by Pb2+ replaced by Ca.2+The complete perovskite phase can be obtained in the PCZ(x) ceramics prepared by co-precipitation, but there are still some impure phases in the PCZ(x) ceramics sintered at the 1280℃, because the increasing temperature will cause the great loss of PbO. Therefore, the sintered temperature of PCZ(x) ceramics prepared by co-precipitation was not suitable too high.The experiment results indicated that the PCZ(x) ceramics was rhombohedral structure when x was 0.25 and 0.30, which can be characeterized used hexagonal system. The PCZ(x) ceramics was orthorhombic structure when x was 0.33 and 0.35. However, the PCZ(x) ceramics was rhombohedral structure again when x was 0.37 or 0.50. The causes were needed to study in the future.The morphology of PCZ ceramics were observed by SEM, and the particles developed very well, the crystal boundary was clear, and the grain size was small. The dielectric constant of PCZ(0.35) prepared by Pechini method is highest when the frequency is between 0~150KHz and the highest dielectric constant(εr) is 138 at 150 KHz. In the PCZ(x)ceramics sintered at the 1200℃, the quality values(Q) of PCZ(0.37)is highest at 0~150KHz,which is 109, but the change of the curvature of Q-f is greatest. Among the PCZ(x) ceramics sintered at 1250℃, whose quality values(Q) increasing with the increasing of frequency, the PCZ(0.35) have the highest Q, which is 45, and Q increases most rapidly with the increasing of frequency.The dielectric constant and dielectric loss of PCZ(x) prepared by solid synthesis were tested in high frequency. It was found that with the increasing of frequency, the dielectric constant of PCZ(x) decreased slowly. When the temperature increased, the dielectric constant of PCZ(x)ceramics also increased when x was constant. The...