Effect of PO2 on Bulk and Grain Boundary Resistance of n‐Type BaTiO3 at Cryogenic Temperatures

摘要: Complex impedance analysis at cryogenic temperatures has revealed that the bulk and grain boundary properties of BaTiO3 polycrystals are very sensitive to oxygen partial pressure during sintering. Polycrystals sintered PO2 as low 10−15 atm were already electrically heterogeneous. The activation energy conductivity in rhombohedral phase was found be close reduced undoped single crystal (i.e., 0.093 eV). increases with temperature postsinter oxidation treatment from 0.064 0.113 eV. Analysis polycrystalline reducing atmosphere then annealed PO2= 0.2 shown onset PTCR effect occurs much higher than expected framework chemisorption model. EPR intensity barium titanium vacancies after T > 1000°C. A substantial is achieved only prolonged annealing ceramic air high 1200–1250°C. This result suggests associated interfacial segregation cation boundaries.