PTCR Characteristic of BaTiO_3 Ceramics Doped with Donor La and Acceptor Mn

摘要

BaTiO_3 semi-conductor ceramics doped with donor La and acceptor Mn are synthesized by sol-gel method. In the doping process, nitrate can be used to substitute for conventional alkoxides in order to realize homogenous doping and improve the components homogeneity of BaTiO_3 ceramics. The relationship between the concentration of acceptor Mn and PTCR characteristic, and microcosmic mechanism of PTCR characteristic are discussed, together with XPS measurement. The results indicate that Mn~(2+) and Mn~(3+) are the main valence state of La-Mn codoped BaTiO_3 ceramics. PTCR characteristic which is enhanced by adding minor amounts of acceptor Mn is showed. According to Heywang model, additional surface potential barrier contributes to the enhancement of PTCR.