Nonlinear current－voltage characteristics of sintered tungsten－vanadium oxide
Liu Zu-Li (刘祖黎)a, Yang Lin-Feng (杨林峰)a, Wang Yu (王豫)a, Wang Chuan-Cong (王传聪)a, Yao Kai-Lun (姚凯伦)b
a Department of Physics and State Key Laboratory of Laser Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China; b Department of Physics and State Key Laboratory of Laser Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China; The International Center of Materials Physics, Chinese Academy of Sciences, Shenyang 110012, China
Abstract We have studied the densification behaviour, microstructure and electrical properties of WO_3 ceramics with V_2O_5 as the additive ranging from 0.5 to 15mol%. Scanning electron microscopic photos indicated that the grain size of WO_3－V_2O_5 specimens is smaller than that of pure WO_3. The addition of V_2O_5 to WO_3 showed a tendency to enhance the densification rate and to restrict the grain growth. Electrical properties of all specimens were measured for different electrodes at different temperatures. The formation of the grain boundary barrier layer was confirmed by the non-ohmic I－V behaviour. The nonlinear coefficient was obtained at the current density J=0.01, 0.1 and 1mA/cm^2 for a series of WO_3－V_2O_5 samples. The V0.5mol% specimen showed an abnormal phenomenon that the nonlinear characteristics appeared at 350℃ and disappeared at lower and higher temperatures. This implies that it could be applied as a high-temperature varistor. The double Schottky barrier model was adopted to explain the phenomena for the WO_3-V_2O_5 varistors.
Received: 30 May 2003
Revised: 15 October 2003
Accepted manuscript online:
PACS:
73.30.+y
(Surface double layers, Schottky barriers, and work functions)
Liu Zu-Li (刘祖黎), Yang Lin-Feng (杨林峰), Wang Yu (王豫), Yao Kai-Lun (姚凯伦), Wang Chuan-Cong (王传聪) Nonlinear current－voltage characteristics of sintered tungsten－vanadium oxide 2004 Chinese Physics 13 522
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