Investigation of Grain-boundary Surface States for (Ba,Pb)TiO3 Positive Temperature Coefficient Ceramics Doped with Different Additives

• Main Authors: Liang-Fu Chen, 陳亮福
• Other Authors: Tseung-Yuen Tseng
• Format: Others
• Language: en_US
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/95867547943205124947

碩士 === 國立交通大學 === 電子研究所 === 83 === The electrical properties of positive temperature coeffici- ent of resistance ceramics of composition (Ba,Pb,La)TiO3 prepar- ed from commercial powders doped with different additives were studied. These additives (Mn,BN,Ca) were commonly either used as sintering aids or served as the acceptor's function. Among them, it was found that BN exhibited a pronounced effect in preventing the volatilization of lead and stabilized the electrical- property performance. It was also proposed here that different additives might have generated the corresponding number of possible surface states, such as, the segregation behavior of Mn ions (3d transition metal), oxygen adsorption reaction resulting from the existence of B at the grain boundary, the action of Ca replacing the Ti sites, even natural intrinsic defects. And, in general, some experimental derivations were also offered that majority of the surface states, which possessed their individual surface energy level, were possibly coexisted onto the grain surface. Utilizing the concept of the coexistence of different types of surface states in energy band, a satisfactory point-to -point agreement was obtained between the measured result and calculated values for the resistivty curve.......