BaxSr1-xTiO3 (0.2≤x≤0.5) ceramics with 10 vol% BaO-SiO2-B2O3 glass addition were prepared. The microstructure and dielectric properties were investigated by XRD, SEM, ferroelectric tester and impedance analyzer. The results show that with the decrease of x, the pulse breakdown strength of the samples is increased, and the dielectric constant and dielectric loss is decreased gradually. In the frequency from 10 kHz to 20 MHz, the dielectric constant of all the samples show good frequency stability. For x=0.2, the samples exhibit high breakdown strength of 37.7 kV/mm, moderate dielectric constant of 311 and low dielectric loss of 5×10-4,which is a promising dielectric for pulsed power applications.
The electrical properties and microstructure of Na2O−PbO−Nb2O5−SiO2 glass-ceramic capacitors with pre-sputtered gold film as the transition layer in electrode design were investigated. SEM observation and EDS analysis showed that the presence of gold transition layer would eliminate enormously the Ag diffusion into the dielectric layer, resulting in a smooth and dense interface contact with less porous defects near the electrode/dielectric layer region. The electrical property results indicated that the leakage current and dielectric loss had decreased by about an order of magnitude and 20%, respectively. These results were explained by the weakened diffusion of silver into dielectric layer due to the presence of gold transition layer in between the silver paste/dielectric interface.
According to the application of the high voltage SiC devices, studying the package of three kinds of SiC dies with different metals. Experiments show that all die wire bonding and shear strength measurement up to standard, and provide three kinds of packages for different applications, at the same time, filling the needs of producing. The purpose of the shear strength test is to determine the integrity of materials used to attach SiC die to package substrates.
The composites have a great use in practical application. In common, the phases in composite have different relative dielectric constant and in order to reveal how the phases with different permittivity affect the composite’s dielectric properties, the experiments were carried out using inorganic and organic composite with different dielectric constant phases to make that clear. The barium niobate-based SiO2system glass–ceramic and fillers-epoxy resin composites were chosen, and the dielectric properties were tested to compare the difference of those composites. The results show that the existence of high dielectric constant phases in composites can improve the permittivity of composites and make the composites present ferroelectric properties, while the dielectric loss can also increased, and the difference in dielectric constant of the phases can decrease the dielectric breakdown strength.
Crystallization of a glass containing high dielectric performance components can be controlled in the nucleation and growth processes in order to meet the requirements of enabling the glass-ceramic dielectric composites to obtain the desired high electric energy storage densitiy. In this paper, the controlled crystallization technique was employed to synthesize glass-ceramic composites with addition of Gd2O3 in BaO-Na2O- Nb2O5- SiO2 glass system. The results show that both the dielectric constant and the breakdown strength of the glass-ceramic composites demonstrate an increasing tendency with the addition of Gd2O3 from 0 mol% to 7 mol% (relative to SiO2), being responsible for remarkable improvement of the energy storage density of the glass-ceramic composites from 1.7 J/cm3 to 4.7 J/cm3.
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