Tungsten Oxide Ceramic Voltammogram

The graph below shows the volt-ampere characteristics of tungsten oxide ceramics sintered at different holding temperatures. The electrical non-linear behavior of varistors typically occurs at current densities in the region of 1-10 mA. From the figure we can see that at 1050 ℃ 1100 ℃ and insulation for two hours of tungsten oxide ceramics, in the current density of 1-10mA region has a non-linear volt-ampere curve. That is, the pressure sensitive characteristics are exhibited.

The other temperature tungsten oxide ceramics are linear voltammetry curve, in line with Ohm's law. Tungsten oxide ceramics at other insulation temperatures have no non-linear electrical properties in the current density range of 1-10 mA. They all exhibit non-linear electrical properties in the current density range of 10-100 mA. Since the non-linear electrical characteristics of tungsten oxide varistor ceramics originate from the great difference of the grain boundary resistance, the sintered tungsten oxide ceramics at 900 ° C, 950 ° C, 1000 ° C and 1150 ° C also have grain boundary resistance difference. It also has non-linear electrical characteristics. But according to the definition of the relevant parameters in the varistor, the turning point of the volt-ampere curve is defined as the turning voltage. The voltage corresponding to the current is the leakage current. It can be seen that samples sintered at 900 ℃, 950 ℃, 1000 ℃ and 1150 ℃ have large leakage current, which is about 10 times higher than that of samples incubated at 1050 ℃ and 1100 ℃.

The tungsten oxide ceramics sintered at 900 ℃, 950 ℃, 1000 ℃ and 1150 ℃ as the varistor will consume a lot of energy. Although the electrical parameters of the tungsten oxide ceramics kept at 1050°C are like those of the tungsten oxide ceramics kept at 1100°C, the tungsten oxide ceramics kept at 1050°C have poor densification.

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