Effects of Test Piece Length, Composition and Measuring Atmosphere on PTCR Characteristic of Porous BaTiO₃-Based Vacuum-Sintered Compacts Added with Partially Oxidized Ti Powder

抄録

The effects of test piece length, composition (additives of Sb and Sr) and kinds of measuring atmosphere (air, O₂, N₂ and H₂) on positive temperature coefficient of resistivity (PTCR) characteristic were investigated for our newly developed (Ba, SrXTi, Sb)O₃ vacuum-sintered compacts added with partially oxidized Ti powder. It was concluded that the development of PTCR characteristic in the compact is surely caused by the bulk property of the compact itself and that both Sb and Sr play no roles in the development of PTCR characteristic. It was suggested that the development of PTCR characteristic in the compact is caused by the adsorption of oxygen at (Ba, Sr)(Ti, Sb)O₃ ceramic grain boundaries and the transformation from ferroelectric-tetragonal phase to paraelectric-cubic phase, in a similar way to that in usual BaTiO₃-based air-sintered compact without partially oxidized Ti powder.