The effect of small changes in sintering temperature on microstructure, electrical properties, dielectric characteristics, and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics was investigated. With the...The effect of small changes in sintering temperature on microstructure, electrical properties, dielectric characteristics, and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics was investigated. With the increase of sintering temperature, the densities of the sintered pellets decreased from 5.54 to 5.42 g/cm3 and the average grain size increased from 4.1 to 11.7 μm. The breakdown field(E1 m A) decreased noticeably from 7138 to 920 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900 ℃ exhibited excellent nonohmic properties, which were 66 for the nonohmic coefficient and 77 μA/cm2 for the leakage current density. Concerning stability, the varistors sintered at 900 ℃ exhibited the strongest accelerated degradation characteristics, with ΔE1 mA =-9.2% for DC accelerated degradation stress of 0.85 E1 m A at 85 °C for 24 h.展开更多
The influence of soaking time on the nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics was investigated. Based on single sintering process, six disk samples of （Sr, Bi, Si, Ta）-...The influence of soaking time on the nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics was investigated. Based on single sintering process, six disk samples of （Sr, Bi, Si, Ta）-doped TiO2-based varistor ceramics were fabricated by sintering at 1 250 ℃ for 0.5-5.0 h. The samples were characterized by X-ray diffraction, voltage-current characteristics, energy spectra, metallographs, breakdown voltages, and apparent dielectric constant. It is found that the breakdown electrical field intensity at a current density of 10 mA/cma decreases from 5.5 to 4.1 V/mm first and then increases to 7.0 V/mm, the nonlinear coefficient increases from 2.39 to 2.62 first and then decreases to 2.42, and the apparent dielectric constant increases from 98 200 to 1l5 049 first and then decreases to 73 865 with the soaking time increasing from 0.5 to 5.0 h. These indicate that the optimal soaking time is 2.0-3.0 h considering both nonlinear electrical behavior and dielectric properties.展开更多
文摘The effect of small changes in sintering temperature on microstructure, electrical properties, dielectric characteristics, and degradation behavior of V-Mn-Nb-Gd co-doped zinc oxide ceramics was investigated. With the increase of sintering temperature, the densities of the sintered pellets decreased from 5.54 to 5.42 g/cm3 and the average grain size increased from 4.1 to 11.7 μm. The breakdown field(E1 m A) decreased noticeably from 7138 to 920 V/cm with the increase of sintering temperature. The varistor ceramics sintered at 900 ℃ exhibited excellent nonohmic properties, which were 66 for the nonohmic coefficient and 77 μA/cm2 for the leakage current density. Concerning stability, the varistors sintered at 900 ℃ exhibited the strongest accelerated degradation characteristics, with ΔE1 mA =-9.2% for DC accelerated degradation stress of 0.85 E1 m A at 85 °C for 24 h.
基金Project(50872001) supported by the National Natural Science Foundation of ChinaProjects(KJ2007B132, KJ2009A006Z) supported by the Scientific Research Foundation of Education Department of Anhui Province, ChinaProject(XJ200907) supported by the Foundation of Construction of Quality Project of Anhui University, China
文摘The influence of soaking time on the nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics was investigated. Based on single sintering process, six disk samples of （Sr, Bi, Si, Ta）-doped TiO2-based varistor ceramics were fabricated by sintering at 1 250 ℃ for 0.5-5.0 h. The samples were characterized by X-ray diffraction, voltage-current characteristics, energy spectra, metallographs, breakdown voltages, and apparent dielectric constant. It is found that the breakdown electrical field intensity at a current density of 10 mA/cma decreases from 5.5 to 4.1 V/mm first and then increases to 7.0 V/mm, the nonlinear coefficient increases from 2.39 to 2.62 first and then decreases to 2.42, and the apparent dielectric constant increases from 98 200 to 1l5 049 first and then decreases to 73 865 with the soaking time increasing from 0.5 to 5.0 h. These indicate that the optimal soaking time is 2.0-3.0 h considering both nonlinear electrical behavior and dielectric properties.
