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ZnO-based varistors have been widely applied in surge protection devices because of their excellent nonlinear current-voltage (I-V) characteristic and energy absorption ability. Manganese is always added into ZnO-based varistors in order to enhance the nonlinear characteristic of materials. In the present work, the dielectric properties of Mn-doped ZnO-Bi2O3 varistors at extremely low temperatures...
ZnO-based varistors have been extensively used for the protection of devices and equipment against voltage surges because of their exceptional nonlinearity in current-voltage characteristics and the ability to absorb large amounts of energy. Since the composition and fabrication process are complicated, impurities are inevitable in the varistors. Sodium impurities are frequently present in the raw...
Lead-free (Ba0.7Ca0.3)(Zr0.2Ti0.8)O3 ceramics (BZT-50BCT) with x wt% (x=0,0.05,0.1,0.2,0.4) dopant (SiO2 and CeO2) were prepared by the conventional solid-state reaction from the industry available raw materials. The doping effect of SiO2 and CeO2 with different concentrations on the microstructures and electric properties of BZT-50BCT ceramics was systematically investigated in the present study...
CaCu3Ti4O12 (CCTO) ceramics as a dielectric material are of potential applications in capacitors and memory devices, however, how to further improve the dielectric properties of CCTO ceramics is still a challenge. The dielectric behavior of this material can be manipulated via the modification in composition, and Si as a glass phase should have an impact on the properties of CCTO ceramics, this work...
The characteristics of raw material powders, such as the purity and average particle size, have a major impact on the microstructure and properties of the CaCu3Ti4O12 ceramics. The properties of CaCu3Ti4O12 ceramics fabricated with nano-size powders (∼30 nm) are compared with those of the samples with submicron powders (0.1∼0.3 μm). It is found that, the samples fabricated with nano-size powders have...
CaCu3Ti4O12 is believed to have a variety of potential applications due to its unusual high dielectric constant and very high thermal stability. Ceramic films of CaCu3Ti4O12 differ from bulk specimens in dielectric and other physical properties. In this paper, the dielectric properties of CCTO thick films are investigated by SEM and dielectric spectra analysis. The difference thicknesses (0.1 mm,...
CaCu3Ti4O12 ceramics were prepared by coprecipitation method. The pH value of reaction solutions plays an important role in the coprecipitation process. First, the pH value of Ti precursor solution must be controlled at around 3, in order to get clear Ti solution. In addition, the pH value of Ca and Cu precursor solution has a great influence on the properties of both precursor and CaCu3Ti4O12 ceramics...
The electrical and dielectric properties of a commercial ZnO-based varistor ceramics were measured in the process of 8/20mus impulse current degradation with a current density of 1725A/cm2. The characteristic of U-I in the pre-breakdown region was mainly investigated. It was found that the varistor voltage U1mA will first increase rapidly with the times of impulse, and then remain stable and finally...
Recently, universal power law becomes widely used. In this paper, it was used to study the ZnO/Bi2O3 ceramics. Bi2O3 is the only additive of ZnO here in order to directly study the effect of Bi2O3 in ZnO. ZnO samples with different content of Bi2O3 were made by the traditional ceramic technique. Then the microstructure of the acid erosion surface was observed by polarized optical microscope, the dielectric...
This paper investigated the dielectric relaxation phenomena on ultrafine BaTiO3. The ultrafine BaTiO3 particles were prepared by hydrothermal method with a size ranging from 100 nm to 260 nm. The precursors used in the preparation were Ba(OH)2middot8H2O powder and TiO2 powder. Temperature dependence of dielectric constant at various frequencies was experimentally investigated. The dielectric relaxation...
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