The preparation of fine-grained positive temperature coefficient resistance with superior electrical properties
The electrical characteristics of positive temperature coefficient resistance (PTCR effects) mainly come from the grain boundary. The useful way to enhance electrical characteristics of PTC ceramics is to decrease the grain size and add the number of grain boundary. In the paper, the grain size and PTCR effects of ceramics were investigated on the effects of the molar ratio of donor and acceptor, the sintering process and high-energy ball milling. The formulation of prepared ceramics were Ba0.8Sr0.2Ti1.01O3+0.03mol% Mn(NO3)2+x mol Y2O3+2wt% SiO2. The grain size of these PTC ceramics was decreased to only 12?m by adding Sr2+ and Y3+ to substitute the A-site barium ions, which were calcined at 1220C and sintered at 1300C after high-energy ball milling for powders. The prepared ceramics exhibited room temperature resistivity of 100?cm, resistance rising rate more than 104unit through the Curie temperature, and relative density between 75% and 90%.
fine-grained ptc donor and acceptor batio3