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NbO doped 0.8BaTiO-0.2(NaBi)(MgTi)O (0.8BT-0.2NBMT) polycrystalline ceramics were prepared by solid state reaction method. 0.8BT-0.2NBMT samples were observed to possess two dielectric peaks, which were attributed to the formation of core-shell structure (Huang et al. in J Eur Ceram Soc 36:533-540, 2015). Longer sintering induced uniform distributions of the additives. The introduction of NbO into 0.8BT-0.2NBMT could obviously bring about the improvement of the dielectric temperature stability, the degradation of the dielectric loss at room temperature and the decrease of the sintering temperature. The 0.8BT-0.2NBMT ceramics doped with 2.0 at% NbO could satisfy the temperature range of the X9R (−55 to 200 °C, △C/C = ±15% or less) characteristics, with a moderate dielectric constant of 1130, low dielectric loss of 0.7%, low sintering temperature of 1050 °C and insulation resistivity of 5 × 10 Ω cm at room temperature, which might be promising for practical use in multilayer ceramic capacitors. The inhomogeneous distribution and the existence of the secondary phases were responsible for this excellent dielectric temperature characteristic. The complex impedance analysis was introduced to elaborate the conduction mechanism. [ABSTRACT FROM AUTHOR]

BaxSr1-xTiO3-(Ba-B-Al-Si-O) glass ceramics (BST-BBAS) with various amounts of CeO2added, were prepared via melt-quenching technique followed by controlled crystallization. X-ray diffraction reveals that the doping of CeO2restrains the impurity phase in the glassceramics. Besides, the dielectric breakdown strength increases to 1488kV/cm with 0.5 mol% CeO2content. Due to the combined effect of quite high breakdown strength and comparatively high dielectric constant, the energy storage density of 3.2 J/cm3was achieved in the glassceramics with 0.5 mol% CeO2, indicating that the CeO2added is an effective method to improve the energy storage density of BST-BBAS glass ceramics. [ABSTRACT FROM AUTHOR]

Ba x Sr 1− x TiO 3 –(Ba–B–Al–Si–O) glass ceramics (BST–BBAS) was prepared via controlled crystallization. The effect of the crystallization temperature on the electric properties of BST–BBAS glass ceramics were investigated. The results show that the BDS first increases with the crystallization temperature rising until the maximum and then changes to decrease. In order to get higher energy storage materials, the microwave treatment was introduced to this study. It was found that microwave treatment restrain the formation of the dendritic microstructure, so that improve the dielectric breakdown strength (BDS) (increased from 1166 kV/cm to 1486 kV/cm). In addition, the relationship between the breakdown properties and activation energy of glass ceramics was investigated. In this study, due to the quite high dielectric BDS and comparatively high dielectric constant, the energy densities reach to 2.8 J/cm 3 (treated at 950 °C by microwave heat method), which is relatively high for bulk materials. [ABSTRACT FROM AUTHOR]

The barium strontium titanate (BaSrTiO) glass-ceramics doped with different content of La were prepared via controlled crystallization. Phase compositions, microstructure and dielectric behaviors were investigated systematically. The results revealed that LaO additives had little influence on the dielectric constant but significantly changed the microstructure of the glass-ceramics, which led to improved breakdown strength (BDS). The optimized energy-storage density of 3.18 J/cm was achieved in the glass-ceramics with 1.0 wt% LaO content which is 2.56 times higher than pure BST glass-ceramics, suggesting glass-ceramics of this composition could be an attractive candidate for energy-storage applications. [ABSTRACT FROM AUTHOR]

(1− x) BaTiO3- x BiYO3 [(1− x) BT- x BY] polycrystalline ceramics were prepared by solid-state reaction method. The ceramics are in tetragonal phase when x ≤ 0.04, transform to pseudocubic at x ≥ 0.06, showing a classic ferroelectric to relaxor transition at x = 0.06, where the phase transition temperature was found to shift to higher temperature with increasing frequency. The dielectric permittivity peaks were analyzed by the modified Curie-Weiss law. Both parameters ΔTdiffuse and ΔTrelaxor were found to increase with increasing BY content, demonstrating a stronger relaxor characteristic. [ABSTRACT FROM AUTHOR]

A series of niobate glass ceramics with varying glass content have been prepared via controlled-crystallization route, and the dielectric properties, the breakdown characteristics and charge–discharge behaviors have been investigated. The correlation between the dielectric breakdown performance and the activation energy was studied by the measurements of the dielectric breakdown strength and impedance spectroscopy. The charge–discharge efficiency was investigated using a charge–discharge system with high-speed capacitor discharge circuit device. It was found that the dielectric breakdown strength and the discharge efficiency strongly depend on the interface polarization based on the results of complex impedance analysis. With the increase of the glass content, the breakdown strength (BDS) and the charge–discharge efficiency show a clear increasing trend, when the content of glass was 60%, the typical G60 sample shows a high BDS of 1300 kV/cm and a high charge–discharge efficiency of 92.5%. [ABSTRACT FROM AUTHOR]

Dense (1 − x )BaTiO 3− x (Na 1/4 Bi 3/4 )(Mg 1/4 Ti 3/4 )O 3 [(1 − x )BT– x NBMT] polycrystalline ceramics were prepared by solid-state reaction method. The detailed structure analysis was performed by X-ray diffraction (XRD) and Raman spectroscopy, confirming that the Ba and Ti sites were partially replaced by Na + /Bi 3+ and Mg 2+ ions, respectively. An obvious structural variation from tetragonal to pseudocubic was observed for sample with x = 0.08–0.12. The lattice parameter for sample with x ≥ 0.12 decreased linearly with x value. Three changing modes in frequency, width and intensity were observed with x value in the Raman spectra, indicating intense changes of local structure, accounting for evolved dielectric and ferroelectric macroscopic properties. The subgrain microstructures were observed by conventional transmission electron microscopy (TEM) imaging with an energy-dispersive X-ray spectroscopy (EDS) attachment. A large number of core–shell grains were detected by TEM dark field, for x = 0.20, which were attributed to the dissolution–precipitation mechanism. In this present study, (1 − x )BT– x NBMT ceramics are considered promising for high temperature capacitor applications. [ABSTRACT FROM AUTHOR]

MgO-doped 0.97BaTiO 3 –0.03BiYO 3 (0.97BT–0.03BY) polycrystalline ceramics were prepared by the solid-state sintering method. Then the structural, dielectric and resistant properties were investigated as functions of MgO addition. Microstructure was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). The results show that Bi 3+ , Y 3+ and Mg 2+ ions exhibit nonuniform distribution behavior in BT–BY ceramics, demonstrating the existence of a “core–shell” structure, which plays important roles in the capacitance-temperature characteristics, where 0.97BT–0.03BY with the addition 2.2–2.8 at% MgO meets the Electronic Industries Association (EIA) X8R (−55 to 150 °C, ΔC / C 25 °C =±15% or less) specification. Moreover, the fine-grained samples with core–shell structure show much higher bulk resistance than the coarse-grained samples over the studied temperature range, which is attributed to the higher proportion of grain boundaries and the lower concentration of the effective acceptor. [ABSTRACT FROM AUTHOR]