Grain-Boundary Chemistry of BaTiO3 based PTCR Ceramics as CO Gas Sensors
BaTiO3基PTCR气敏陶瓷的晶界化学研究

The sensing phenomena and mechanism of doped BaTiO_3 based PTCR ceramics for chemical sensors are close related to the variation of chemical defect structure in the grain bound- aries 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.