The Microstructures and Grain Boundary Segregations of Ceramic Barium Titanate Processed in Microwave Field
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The Microstructures and Grain Boundary Segregations of Ceramic Barium Titanate Processed in Microwave Field Hanxing Liu, Zhongqin Tian, Jian Zhou, Hongtao Yu, Long Zou, Shixi Ouyang State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070, P.R. China ABSTRACT Ceramic sintering in microwave field is a new ceramic processing method. In present paper, we detected the microstructures and boundary segregation of BaTiO3 ceramics which were sintered in microwave field. Scanning electron microscopy(SEM), and transmission electron microscopy(TEM) , and chemical analysis methods were employed to detect the microstructure of BaTiO3, element distribution near the boundary of BaTiO3 ceramic. The results shown growth of grain of the ceramic was influenced by impurities such as acceptor, benefactor et al, and the element distribution near the grain boundary of BaTiO3 sintered in microwave field were different with that sintered in conventional method. The boundary segregations of BaTiO3 sintered in microwave field were not obvious as compared to the conventional method because the diffusion was enhanced due to the microwave field. INTRODUCTION Ceramic sintering and synthesis in a microwave field were started from the 1980’s. The research results shown it is a special materials processing techniques[1-7]. For example D. Blake[8] shown that Al2O3+SiC could be processed by employing 2.45GHz, 700W microwave furnace. The ceramics could be obtained in 60 minutes. I. Ahmad[9-10] used microwave sintering technology to obtain other ceramics. Interest remains regarding the difference in conventional sintered versus microwave sintered materials especially as it pertains to segregation at boundary or interface of ceramics. The purpose of those research works tried to make clear the mechanism of microwave sintering and synthesis, so that it could be used widely. The mechanism of the enhanced effects by microwave field is a debatable topic[12]. Due to the serious of the problem, peoples still work on this some basic topic about the microwave sintering and synthesis. The physics and chemistry of grain boundaries of perovskite ferroelectrics ceramic control their properties, such as impurity of BaTiO3, SrTiO3, PbZr1-xTixO3 influences greatly the properties of ceramics. BaTiO3 ceramics is a kind of important electronic ceramics, and its boundary segregations is really a basic research topic for its applications. As we know, the impurity in BaTiO3 greatly influenced on the properties of ceramics[13-16]. For example state of BaTiO3 could be changed from insulator to semiconductor when only 0.1 at% La impurity was added in ceramic due to the segregation of the impurity in the grain boundary. D.B. Desu[17] suggested a theoretical model to analyze the segregations of boundary in the BaTiO3 ceramics. The purpose of present works tries to get in detail the difference of segregation of BaTiO3 ceramics sintered in microwave field and sintered in conventional me
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