超细晶钛酸钡基储能陶瓷的性能与微观结构

利用水基化学包覆法在纳米钛酸钡粉体包覆氧化铝、二氧化硅和氧化锌等物质,并通过两段式烧结法制备了平均晶粒尺寸120 nm的超细晶钛酸钡基储能陶瓷.包覆层的存在抑制了晶粒生长和异常晶粒长大,同时将陶瓷的交流击穿场强大幅提高至150 kV·cm-1以上,储能密度达到0.829 J·cm-3.电子能量损失谱显示,包覆掺杂的元素明显偏聚于陶瓷晶界,形成具有芯-壳结构的晶粒.而高温阻抗谱的测试和拟合结果则进一步解释了陶瓷性能改善的原因.虽然此超细晶陶瓷的储能密度并不十分突出,但其晶粒细小均匀、烧结温度低,因而可用于制备多层陶瓷电容器,从而大幅提高储能密度,这是常见的储能陶瓷无法实现的.

Properties and microstructure of ultrafine-crystalline BaTiO3-based energy storage ceramics

Al2 O3 , SiO2 and ZnO were coated around nano-sized BaTiO3 particles by means of aqueous chemical coating. Then, BaTiO3-based energy storage ceramic material with average grain size of 120 nm was fabricated by the two-step sintering method. The coating layer can restrain grain growth and abnormal grain growth, and can enhance significantly the AC breakdown strength of the ma-terial to over 150 kV·cm-1 , while providing energy density of 0. 829 J·cm-3 . Energy-dispersive spectroscopy proves the gathering of doping elements near grain boundaries, thus indicating the existence of a core-shell structure. High-temperature impedance spectrosco-py and fitting results further explain that the energy storage properties were improved. Although the energy density of this ultrafine-crystalline ceramic material is moderate, the advantages of fine grains and low sintering temperature make it possible for the material to be used in multilayer ceramic capacitors, which can increase energy storage by orders of magnitude. This improvement is impossible to achieve with conventional energy storage ceramics.