Strontium Titanate Varistor

In this paper, The basic theories, basic electrical properties, basic applications and the developing status were discussed, then the ceramic materials used for SrTiO₃ varistor and the preparing process were presented and systematic researched through abundant experiments. Theory analyses were also explored to explain the phenomenon and law of the relative experiments.For the ceramic materials,The effects of the Sr/Ti ratio, donor additives Nb₂O₅,La₂O₃, acceptor additives MnO₂, sintering aid additive SiO₂, BaTiO₃ and CaTiO₃ additives which with perovskite crystal structure, alkali metal ion compound Na₂CO₃,Li₂CO₃ were discussed. The suitable Sr/Ti ratio can promote grain growth. The suitable adding donor additives Nb₂O₅,La₂O₃ make the grain semiconducted and better electrical properties can be gotten . CaTiO₃ dopant makes the electrical properties better. The suitable adding acceptor promotes the the non-linear coefficientα, specially when adding Li+ and Na+.For preparation process, the synthesization processing, sintering processing, electrode plasm were systematic studied. One-step synthesization made the electrical properties more stable, controling the reducing sintering temperature and retention time can adjust the electrical properties in a certain scope, changing the oxidation temperature made the varistor's voltage V10mA changed, using the special double-layer silver plasm can eliminate the voltage-direction problem.The varistor ceramic materials power was made by one-step synthesization, using the optimized ingredient makeup and preparation processing , the homogeneous and compact grain and the electrical properties of V10mA≤6.5V,α≥4.7 , C≥3.4×10-3F·m-2, tgδ≤22% can be obtained .