Effects of MnO Doping on The Dielectric Properties and Microstructure of BaTiO3 with specification of X8R

• Main Authors: Yu-Sheng Zheng, 鄭煜昇
• Other Authors: Tsang-Tse Fang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/97684098579610737816

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 96 === In recent years, capacitor is required to have excellent temperature characteristics. In particular, in some applications, it is desired that the temperature characteristics be smooth under harsh conditions. Multi-layer ceramic capacitors, like X8R, have some into use for various types of electronic equipment such as the engine electronic control units (ECU) mounted in engine compartments of automobiles, crank angle sensors, antilock brake system (ABS) modules, etc. These types of electronic equipments are used for stabilizing engine control, drive control, and brake control. The environment in which these types of electronic equipment are used is envisioned to be one in which the temperature fall s to as low as -20˚C or so in the winter in cold areas or the temperature rises to as high as +130˚C or in the summer right after engine startup. Therefore, these types of electronic equipment are required to have excellent circuit temperature stability. In this study, the increasing of MnO-doping decreases the dielectric permittivity. However, tangent loss and ΔC/C25˚C in high temperature range increased with additional MnO. In the aspect of microstructure, Mn prohibits the grain growth by decreasing the grain boundary mobility due to a high concentration of Mn near the grain boundary. Furthermore, Mn concentration also has important influence on the relaxor behavior. With increasing dopant of Mn, the BaTiO3 solid solution shows a decreased degree of deviation from the modify Curie–Weiss law. It indicates a crossover from relaxor behavior to a normal ferroelectric state, and results the reduction of relaxor behavior.