Abstract In polycrystalline ceramics, charge trapping property has important impact on the dielectric breakdown strength (DBS). In this work, alumina ceramics with Ca9Al(PO4)7(CAP) as the second crystalline phase were synthesized using coarse alumina as main raw materials, and the CAP crystal being dendritic or granular depends on the mass ratio of calcium phosphate to kaolin in the raw material composition. Microstructure and impedance spectrum indicated that dendritic CAP with typical fractal features greatly increases the charge trapping sites and charge spreading barrier. The AC DBS of ceramics with 70 wt% alumina and fractal dendritic CAP achieved a competitive value of 16.1 kV/mm. The results indicate that growing fractal dendritic CAP between the main crystalline grains is a very feasible way to enhance the DBS of alumina ceramic.

中文翻译：

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分形枝晶Ca9Al(PO4)7作为第二晶相增强氧化铝陶瓷的介电击穿强度

摘要 在多晶陶瓷中，电荷俘获性能对介电击穿强度（DBS）有重要影响。本工作以粗氧化铝为主要原料，合成了以Ca9Al(PO4)7(CAP)为第二晶相的氧化铝陶瓷，CAP晶体呈树枝状或颗粒状，取决于其中磷酸钙与高岭土的质量比。原料组成。微观结构和阻抗谱表明，具有典型分形特征的树枝状 CAP 大大增加了电荷俘获位点和电荷扩散势垒。具有 70 wt% 氧化铝和分形枝晶 CAP 的陶瓷的 AC DBS 达到了 16.1 kV/mm 的竞争值。结果表明，在主晶粒之间生长分形枝晶CAP是提高氧化铝陶瓷DBS的一种非常可行的方法。