Magnetic properties of iron-based soft magnetic composites with SiO2 coating obtained by reverse microemulsion method

Influence of zinc on electrical and microstructural properties of CaCu3Ti4O12 ceramics prepared by sol–gel process

Microstructure and electrical properties of Sc2O3-doped ZnO–Bi2O3-based varistor ceramics

The ZnO-Bi2O3-MnO2-xSiO2 (ZBMS) varistor was prepared at a low sintering temperature of 880 °C via the conventional solid state method The phase transformation, microstructure, and electrical properties of the ZBMS varistor were studied as a function of doping amount of SiO2 It is showed that the growth of ZnO grain is restrained by the introducing of SiO2; and the grain size decreases from 468 μm to 298 μm The breakdown voltage E1mA exhibits a simultaneous variation from 60811 V/mm to 123288 V/mm It is also revealed that SiO2 has a significant effect on the Schottky barrier structure As a result, the highest barrier height φb of 534 eV is attained at a composition of x = 20 wt%, which contributes to the highest nonlinear coefficient α of 7368 Moreover, all the samples show low leakage current of IL

Influence of SiO2 on electrical properties of the highly nonlinear ZnO-Bi2O3-MnO2 varistors

Microstructure and electrical properties of Y(NO3)3·6H2O-doped ZnO-Bi2O3-based varistor ceramics

The microstructure and electrical properties of ZnO-based varistors with the SiO2 content in the range of 0–1.00mol% were prepared by a solid reaction route. The varistors were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometry, inductively coupled plasma-atomic emission spectrometry, and X-ray photoelectron spectroscopy. The results indicate that the average grain size of ZnO decreases with the SiO2 content increasing. A new second phase (Zn2SiO4) and a glass phase (Bi2SiO5) are found. Element Si mainly exists in the grain boundary and plays an important role in controlling the Bi2O3 vaporization. The electric measurement shows that the incorporation of SiO2 can significantly improve the nonlinear properties of ZnO-based varistors, and the nonlinear coefficients of the varistors with SiO2 are in the range of 36.8–69.5. The varistor voltage reaches the maximum value of 463 V/mm and the leakage current reaches the minimum value of 0.11 μA at the SiO2 content of 0.75mol%.

Jian-hui Fang

Papers

Effect of SiO 2 addition on the microstructure and electrical properties of ZnO-based varistors