BaTiO_3基PTCR气敏陶瓷的晶界化学研究

Grain-Boundary Chemistry of BaTiO_3 based PTCR Ceramics as CO Gas Sensors

陶瓷化学传感器的敏感机制与品界的化学缺陷结构在周围微环境下的变异密切相关.晶粒表面和晶界是空位源,研究陶瓷材料在环境气氛中晶界化学缺陷的变化,对于探索陶瓷材料的敏感机制和开拓新应用具有重要意义.本文就BaTiO_3基PTCR陶瓷中本征缺陷的生成和分布,缺陷在高温冻结、吸附和脱附过程中的变化,缺陷的重分布及其对晶界势垒的贡献进行深入的讨论.

The sensing phenomena and mechanism of doped BaTiO3 based PTCR ceramics for chemical sensors are close related to the variation of chemical defect structure in the grain boundaries with environmental atmospheres. The surfaces and grain boundaries are act as a uniform source and sink for vacancies, and the lattice defects play a positive role for the sensing effect in the ceramics. The grain boundary chemistry, specially, formation and distribution of defects, defect changes in adsorption and desorption process with surrounding CO gas, redistribution of electrons on quenching to room temperature for high dopant concentrations as well as potential barrier in grain boundary were discussed.