The subsolidus phase relations of a ZnO-V2O5-K2O system are investigated by X-ray powder diffraction. There is 1 ternary compound, 11 binary compounds and 14 three-phase regions in this system. The phase diagrams of V...The subsolidus phase relations of a ZnO-V2O5-K2O system are investigated by X-ray powder diffraction. There is 1 ternary compound, 11 binary compounds and 14 three-phase regions in this system. The phase diagrams of V2O5- K2O with the K2O content ranging from 0 to 71 mol% and pseudo-binary system of ZnO-K2ZnV2O7 are also studied by X-ray powder diffraction and differential thermal analysis methods.展开更多
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 effect of Mn_(3)O_(4)addition on microhardness,microstructure and electrical properties of vanadium oxide doped zinc oxide varistor ceramics is systematically investigated.The Vicker’s microhardness HV has decrea...The effect of Mn_(3)O_(4)addition on microhardness,microstructure and electrical properties of vanadium oxide doped zinc oxide varistor ceramics is systematically investigated.The Vicker’s microhardness HV has decreased with increasing the amount of Mn3O4.Also,the average grain size has decreased from 27.51μm to 19.55μm with increasing the amount of Mn_(3)O_(4) up to 0.50 mol%,whereas an increase in Mn_(3)O_(4) up to 0.75 mol%has caused the average grain size to increase and then it decreases with increasing Mn_(3)O_(4)from 0.75 mol%to 1.00 mol%.The sintered density has decreased from 5.38 g/cm3 to 5.31 g/cm3 with increasing the amount of Mn_(3)O_(4).The varistor ceramic modified with 0.50 mol%Mn_(3)O_(4) has exhibited excellent nonlinear properties,with 16.29 for the nonlinear coefficient and 441.9μA/cm2 for the leakage current density.Furthermore,the sample doped with 0.50 mol%Mn_(3)O_(4) has been found to possess donor density as 0.77×10^(18) cm^(-3) and 0.916 eV barrier height.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.50672123)
文摘The subsolidus phase relations of a ZnO-V2O5-K2O system are investigated by X-ray powder diffraction. There is 1 ternary compound, 11 binary compounds and 14 three-phase regions in this system. The phase diagrams of V2O5- K2O with the K2O content ranging from 0 to 71 mol% and pseudo-binary system of ZnO-K2ZnV2O7 are also studied by X-ray powder diffraction and differential thermal analysis methods.
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.
文摘The effect of Mn_(3)O_(4)addition on microhardness,microstructure and electrical properties of vanadium oxide doped zinc oxide varistor ceramics is systematically investigated.The Vicker’s microhardness HV has decreased with increasing the amount of Mn3O4.Also,the average grain size has decreased from 27.51μm to 19.55μm with increasing the amount of Mn_(3)O_(4) up to 0.50 mol%,whereas an increase in Mn_(3)O_(4) up to 0.75 mol%has caused the average grain size to increase and then it decreases with increasing Mn_(3)O_(4)from 0.75 mol%to 1.00 mol%.The sintered density has decreased from 5.38 g/cm3 to 5.31 g/cm3 with increasing the amount of Mn_(3)O_(4).The varistor ceramic modified with 0.50 mol%Mn_(3)O_(4) has exhibited excellent nonlinear properties,with 16.29 for the nonlinear coefficient and 441.9μA/cm2 for the leakage current density.Furthermore,the sample doped with 0.50 mol%Mn_(3)O_(4) has been found to possess donor density as 0.77×10^(18) cm^(-3) and 0.916 eV barrier height.
