Tungsten Oxide Doped Yttrium Oxide

To use tungsten oxide as a low-voltage capacitor-varistor material in practice, it is necessary to solve the problem of its electrical stability. Previous research shows that the electrical properties of tungsten trioxide are not stable. In the case of high electric fields, there is a serious problem of electrical degradation. The current decays with time under constant voltage and there is a serious hysteresis. Obstructed its application as a varistor material in practice.

Tungsten oxide has significant electrical degradation characteristics at high electric fields. In stark contrast to this, the volt-ampere characteristics of yttria-doped samples are basically unaffected by DC polarization. Doped yttrium oxide can better solve the stability problem of electrical properties in tungsten oxide ceramics. In general tungsten oxide ceramics, the instability of the electrical properties results from the polarization caused by the coexistence of the two phases of the grain phase structure. Doping cerium oxide simulates its phase structure, thereby stabilizing the electrical properties. The stability of electrical performance is beneficial to its application as a varistor material. Doped with germanium will affect the grain growth of tungsten oxide ceramics. The larger the doping amount, the larger the grain size.

In the cerium-doped tungsten oxide ceramics, only monoclinic tungsten oxide exists. This shows that cerium doping can significantly suppress the formation of triclinic tungsten oxide, which makes tungsten oxide single phase. The sample with 1% doping has a varistor voltage of only 4.9 V/mm. The barrier voltage is very small, only about 0.06V, indicating that tungsten oxide is particularly suitable for low voltage varistors. Erbium doping does not improve the nonlinear coefficient of the system. Erbium doping can improve the stability of the electrical properties of tungsten oxide ceramics under high electric fields, which is related to the singulation of the phase structure. It is also stable at low electric fields, which indicates that the ion migration in the depletion layer is weak. Therefore, tungsten oxide has a good application prospect in the low voltage area. Germanium doping can significantly increase the dielectric constant of tungsten oxide ceramics.

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