SrTiO_3 Based Dual-Functional Ceramics with Nano-Additives

摘要

The electrical properties and microstructures of SrTiO_3 based voltage-sensing and dielectric dual-functional ceramics with nanometer donor and acceptor additives were studied. The La_2O_3 nano-powders and MnO-SiO_2-Al_2O_3 (or CuO-SiO_2-Al_2O_3) nano-composite powders were incorporated into SrTiO_3 as donor, acceptor and liquid-phase sintering aids. Then semiconducting SrTiO_3-based ceramics were sintered at 1360-1440°C for 2 h in a reducing atmosphere. The effects of the nanometer donor and acceptor additives and the sintering temperature on the electrical properties and microstructures of materials were discussed. The results showed that SrTiO_3-based varistor ceramics with 1.1 mol% La_2O_3 and 0.1 mol% MnO nano-additives sintered at 1360-1420°C in graphite and N_2 reducing atmosphere have excellent voltage-sensing and dielectric characteristics. The varistor voltage ranges from 2.3 to 5.3 V/mm, the nonlinear coefficient from 3.0 to 3.8, and the dielectric constant from 215,600 to 413,000.