Study On The Doped Strontium Titanate Varistor Multi-Function Materails

In this paper, the domestic and overseas developing status, multifunction characteristics, specific applications and the basic theories of SrTiO3capacitor-varistor multifunction ceramics were discussed, then the ceramic materials and the preparing processes were researched through abundant experiments. The phenomenon and law of the relative experiments were also been explained through the theory analyses. The results of experiment are showed below:(a) The effect of the Ti/Sr ratio was discussed. The suitable Ti/Sr ratio could promote grain growth. When the Ti/Sr ratio was equal to1.02, the electrical properties and the level of semiconducting in the SrTiO3ceramics were better in contrast with other ratios.(b) The electrical properties of the double donor dopants were better in contrast with the single donor dopants. The better electrical properties were get when the doping amount of La2O3andNb2O5were equal to0.5mol%.(c) The resistivities of vaccum sintered SrTiO3ceramics were increased after the heating treatment in air, so the acceptor dopants Mn2+and Cu2+ions did not affect the semiconducting of grains, they only affected the electrical properties of grain boundaries; The grain sizes of CuO doped ceramic were larger than those of MnCO3doped ceramic with the same contents under the same sintering conditions, and CuO doped ceramic could increased the acceptor state density at the grain-boundary regions, so CuO doped ceramic possessed relative higher dielectric constant and lower varistor voltage in contrast with MnCO3doped ceramic.(d) SiO2、Li2CO3were also declined the sintered temperature, SiO2doped ceramic possessed better microstructure and total level of electrical properties in contrast with Li2CO3doped ceramic, the varistor voltage of Li2CO3doped ceramic was too high; The total levels of electrical properties were improved with the increase of doping amount of SiO2. When the doping amount of SiO2was equal to0.6mol%, the grain sizes were average, and the structures of SrTiO3multifunction ceramics were compact. It’s got good SrTiO3multifunction ceramics which electrical properties are ε=1.26×105～4.32±105, V1mA=4.8～13.6V, α=5.15～9.50by oxidizing heat treatment after being sintered for2hrs.