Low Sintering Temperature Behavior and Dielectric Properties of (Ba,Ca)(Ti,Zr,Mn)O3 in a Reducing Atmosphere

• Main Author: 吳平宏
• Other Authors: Tsang-Tse Fang
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/72818965619427188708

碩士 === 國立成功大學 === 材料科學及工程學系 === 87 === (Ba,Ca)(Ti,Zr,Mn)O3 would possess high dielectric constant. Because of the utilization of the base metals such as Ni and Cu, the multilayer capacitor must be sintered in a reducing environment and at lower temperature to reduce the stress of interface. The purposes of this study were to evaluate the effect of flux additive of MST on the sintering behavior and the dielectric properties in the different atmospheres. It was found that the reducing environment could enhance the sintering rate. It prevents the formation of the liquid phase and delays the diffusion of calcium ions into barium titanate. But it will be dedensified owing to the pore growth. The sintering temperature could be lowered to 1100℃ when more than 2% MST were added . The more MST was added, the more uniform the grains were but the more the pore growth was. Reducing atmosphere would enhance dielectric constant, in which Mn+3 would become Mn+2 and the Curie temperature would shift from 65℃ to 30℃. Higher sintering temperature would develop more oxygen vacancies which in turn would lower resistance and enhance dielectric loss. Mn would diffuse in BCTZM when MST was added, which would reduce dielectric loss and dielectric constant and make Curie temperature shift to lower temperatures. For preparing MnSiO3 and MnTiO3, the mixture of MnO2 and SiO2 was calcined in air to form MnMn6SiO12 first. At 1200℃, it melted and did not form MnSiO3 completely. However, when it was calcined at 1100℃ for 8 hours in the reducing atmosphere, more pure MnSiO3 could be obtained. MnTiO3 could be synthesized at 1250℃ for 4 hours in a reducing atmosphere. MST calcined in different atmospheres would possess different colors, which might be due to the different oxidation states of Mn.