Hybrid Microwave Sintering for PZN-based Ceramics System and Manganese Addition to Improve Quality Factor

• Main Authors: Chia-Hung Li, 李佳鴻
• Other Authors: ccchou
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/guc37n

碩士 === 國立臺灣科技大學 === 機械工程系 === 95 === In the present study, microstructure and electric properties of 0.4(Pb(Zn1/3Nb2/3)O3)+0.6PbZr0.52Ti0.48O3 (0.4PZNZT) specimen sintered by conventional and microwave sintering processes were successfully investigated and correlated. Microwave sintering is adopted to process the specimens at lower temperatures and for shorter times by rapid heating to avoid the high temperature and long sintering time in the conventional process. Moreover, the mechanism of microwave sintering process for the enhancement in properties is discussed. Better densification is achieved in the specimens of microwave sintered at temperatures lower than conventional sintering temperatures and the pyrochloric phase is also found to eliminate by rapid heating and cooling rates of microwave sintering. The average grain size of microwave sintered specimens is smaller than the conventional sintered specimens. From the kinetics of grain growth, the calculated activation energies for grain growth of microwave and conventional sintering specimens are 134 and 290 kJ/mol, respectively. Microwave sintering decreased the activation energy for grain growth in the specimens and caused faster condensing phenomenon. Because of faster heating rate in microwave sintering, the overall grain growth was restricted and improved the electric properties. Higher remnant polarization (45.67 μC/cm2) and electromechanical coupling coefficient (0.726) in the specimen of microwave sintered at 1100 ℃ for 1 hr is found to be higher than the remnant polarization (43.62 μC/cm2) and electromechanical coupling coefficient (0.681) of the conventional sintered specimen at 1150 ℃ for 2 hr. Addition of 0.3 wt% MnO2 to 0.4PZNZT reduced the electromechanical coupling factor from 0.681 to 0.606, but the mechanical quality factor increased from 61 to 178 and dielectric loss decreased from 3.8% to 0.58%. Higher quality factor and low loss with the addition of MnO2 to 0.4PZNZT are the requirements to use this material for device applications. Furthermore, better densification is achieved in the specimens of microwave sintered addition of 0.3 wt% MnO2 at lower temperature and soaking times. Because of oxygen vacancies distributed not uniform to cause incapable improvement electromechanical coupling factor.