Abstract
The effect of CuO addition on the properties of (Co, Nb, Cr)-doped SnO2 varistors were investigated. The samples with different CuO concentrations were fabricated by the conventional ceramic method and sintered at 1,200, 1,250, 1,300 and 1,350 °C for 2 h. It is found that the nonlinear coefficient presents a peak value at 0.2 mol % CuO addition. The leakage current density decreases with increasing CuO from 0 to 0.2 mol %, and then increases when the concentration of CuO is above 0.2 mol %. The breakdown electrical field decreases from 356 to 248 V/mm with increasing CuO from 0 to 0.6 mol %. The optimal samples obtained by doping CuO with 0.2 mol % and sintered at 1,300 °C have the highest nonlinear coefficient value of 31 and the lowest leakage current density of 2 μA/cm2.
Highlights
The rutile crystalline structural SnO2 is an n-type semiconductor with many interesting electronic properties
The leakage current density decreases with increasing CuO from 0 to 0.2 mol %, and increases when the concentration of CuO is above 0.2 mol %
The optimal samples obtained by doping CuO with 0.2 mol % and sintered at 1,300 °C have the highest nonlinear coefficient value of 31 and the lowest leakage current density of 2 lA/cm2
Summary
The rutile crystalline structural SnO2 is an n-type semiconductor with many interesting electronic properties In the past, it is widely used in gas sensors and wet sensors. Many dopants have been studied, such as ZnO, CoO, MnO, Nb2O5, CuO, Ta2O5, Cr2O3, Al2O3 [5,6,7,8,9,10,11,12,13]. ZnO, CoO, MnO have significant role to improve the density, Nb2O5 and Ta2O5 mainly improve the conductivity, and Cr2O3 and Al2O3 mainly improve current–voltage characteristic of SnO2-based ceramics. The effects of CuO addition and sintering temperature on the microstructure and electrical properties of the Co2O3–Nb2O3–Cr2O3 doped SnO2 varistors were investigated in detail. It is found that CuO addition and sintering temperature could adjust the microstructure, and as a result, the breakdown electrical field decreases, the nonlinearity improves and the leakage current decreases
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