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《Journal of the European Ceramic Society》2022,42(1):162-168
Excellent electrical properties and the improved long-term stability of ZnO varistor ceramics were simultaneously achieved by doping NiO. The microstructural features were investigated using X-ray diffractometer, scanning electron microscopy, and energy dispersive spectroscopy, while the intrinsic point defects were characterized using frequency domain dielectric spectroscopy and verified by photoluminescence and Raman spectra. The results indicated that in the ZnO varistor ceramics, a reverse manipulation of donor point defects, i.e., suppressing mobile zinc interstitial but increasing stable oxygen vacancy, was achieved. The long-term stability of NiO-doped ZnO ceramics was improved via a decrease in zinc interstitial density, with a degradation rate of 0.064 μA cm?2 h?0.5. Meanwhile, due to an increase in oxygen vacancy density, the excellent nonlinear current–voltage performance, i.e., a high nonlinear coefficient (72.9), low leakage current density (0.08 μA cm?2), and low grain resistivity (13.43 × 10?3 Ω m), was maintained. The findings of this study provide a possible method for developing high-performance ZnO varistor ceramics by manipulating point defects. 相似文献
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为解决常规配电网网格化规划方法中网格(单元)划分比较粗放、在一定投资约束下难以合理选取建设项目等问题,本文提出一种配电网网格化优化规划方法。首先构建诊断分析指标体系,对现状配电网进行评分,通过与一流配电网指标对比来诊断出配电网的薄弱环节;然后研究细化、可操作、闭环化管理的配电网供电网格(单元)划分方法,对供电网格(单元)进行差异化划分;然后研究配电网目标网架构建流程,根据典型接线模式、现状问题需求和未来发展需求,确定目标网架和过渡网架,并对目标网架、供电网格(单元)合理性进行校验;最后,研究项目优选计算方法,实现配电网投资效益的最大化。 相似文献
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《Ceramics International》2023,49(19):31152-31162
There is still a problem of low energy storage density in dielectric capacitors which is a core component of power systems. For the improvement of the energy storage density, the linear dielectric material CaTiO3 (CT) was introduced in Na0.5Bi0.5TiO3 (NBT) ceramics in this paper. By modifying the A site, a new relaxor ferroelectric ceramic was successfully synthesized and attained a recoverable density (Wrec) of 2.34 J/cm3 at x = 0.18. Moreover, the preparation process was optimized in this paper. Through the viscous polymer process (VPP) route, the energy density (WA) of 82NBT-18CTVPP ceramic further reaches 6.45 J/cm3 at 340 kV/cm, with efficiency (η) up to 75% and a Wrec of 4.82 J/cm3. At the same time, the change of Wrec is small at temperature (30–150 °C) and frequency (1 Hz–300 Hz), which demonstrates its excellent stability. The discharge power density reaches about 180 MW/cm3 and the discharge time is 0.117 μs, which indicates its excellent pulse discharge performance. The results show that 82NBT-18CT lead-free relaxation ferroelectric material is expected to become ideal for high-energy storage applications. 相似文献
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接地测量引线存在互感,严重影响大型接地系统接地阻抗测量结果的准确性。首先推导了任意布线形式接地测量的互感理论模型,并基于引线互感修正项的复镜像拟合实现了模型求解。与更正的穿透深度公式的对比结果表明,复镜像法求解互感的精度较高。研究了5D-0.618法、2D-30度夹角法、90度夹角法和反向法在不同引线长度和土壤电阻率情况下的互感数值规律。结果表明:5D-0.618法和2D-30度夹角法在大型接地系统的阻抗测量时互感导致结果偏大,需要进行互感校正;反向布线法互感为负值,其互感影响程度需要结合工程实际作评估。 相似文献