摘要
铌酸钠基介电储能材料具有相对密度低、无铅及低成本等优点,能够满足电子元器件向小型化、无害化、集成化和轻量化方向发展的重大需求.本文通过在NaNbO3陶瓷中同时引入Bi(Mg0.5Sn0.5)O3和(Bi0.5Na0.5)0.7Sr0.3TiO3组分,采用传统固相烧结法制备(1-x)[0.93NaNbO3-0.07Bi(Mg0.5Sn0.5)O3]-x(Bi0.5Na0.5)0.7Sr0.3TiO3(简称(1-x)(NN-BMS)-xBNST,0≤x≤0.30)弛豫铁电陶瓷,并利用X-射线衍射、扫描电子显微镜、紫外光谱和拉曼光谱等技术对陶瓷进行表征,研究(Bi0.5Na0.5)0.7Sr0.3TiO3掺杂对NaNbO3陶瓷的物相组成、微观形貌以及介电和储能等电学性能的影响.0.75(NN-BMS)-0.25BNST陶瓷具有优良的介电温度稳定性(25-160 ℃,△ε/ε25 ℃±15％)和介电频率稳定性,满足EIAZ8U标准,具备在特殊环境下(高温/高频)工作的潜力.另外,0.75(NN-BMS)-0.25BNST陶瓷在较高的场强下(390 kV/cm)获得了良好的储能性能:有效储能密度Wrec=2.73 J/cm3,储能效率η=82.6％,且性能在20-100 ℃的温度范围内具有高的温度稳定性.研究表明0.75(NN-BMS)-0.25BNST陶瓷在无铅介电储能电容器中有着广阔的应用前景.
Abstract
Sodium niobate-based dielectric energy storage materials,as key components in capacitors,have the advantages such as low relative density,lead-free,low cost,and excellent energy storage density,and can meet the important requirements of electronic components for miniaturization,harmlessness,integration and light weight.Therefore,they have received extensive attention from the scientific community in recent years.In this work,by introducing both Bi(Mg0.5Sn0.5)O3 and(Bi0.5Na0.5)0.7Sr0.3TiO3 components into NaNbO3 ceramics,a conventional solid-phase sintering method is used to prepare(1-x)[0.93NaNbO3-0.07Bi(Mg0.5Sn0.5)O3]-x(Bi0.5Na0.5)0.7Sr0.3TiO3(Abbreviated as(1-x)(NN-BMS)-xBNST,0 ≤ x ≤ 0.3)relaxation ferroelectric ceramics,and the ceramics are characterized by using X-ray diffraction,scanning electron microscopy,UV spectroscopy and Raman spectroscopy so as to study the effects of(Bi0.5Na0.5)0.7Sr0.3TiO3 doping on the physical phase composition,microstructure,and electrical properties of NaNbO3 ceramics,such as dielectric and energy storage.The(1-x)(NN-BMS)-xBNST ceramics exhibit a single perovskite structure,with cell volume a first increasing and then decreasing.The coexistence of Pbma and Pnma phases(1-x)(NN-BMS)-xBNST ceramics exhibits a dense microstructure and clear grain boundaries at an optimal sintering temperature.The average grain size first increases to 4.73 μm,then decreases to 2.17 μm,and finally increases to 3.06 μm.A smaller grain size and a larger bandgap width are beneficial for improving the breakdown strength.The 0.75(NN-BMS)-0.25BNST ceramic shows the excellent dielectric temperature stability(25-160 ℃,△ε/e25℃≤±15％)and dielectric frequency stability,which can meet the EIAZ8U standard and hence work in a special environment(high temperature and high frequency).Meanwhile,0.75(NN-BMS)-0.25BNST ceramic exhibits excellent energy storage performance at high field strength(390 kV/cm):recoverable energy density Wrec=2.73 J/cm3,energy storage efficiency η=82.6％,and high temperature stability in a temperature range of 20-100 ℃.The research results indicate that 0.75(NN-BMS)-0.25BNST ceramics have broad prospects of applications in lead-free dielectric energy storage capacitors.
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