NaCu3Ti3Sb0.5Ta0.5O12陶瓷的高介电性质及相关机制的研究

在不同烧结温度下, 利用传统的固相反应工艺制备了一系列NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂陶瓷, 系统测试了它们的晶体结构、微观结构、介电性质和复阻抗谱。结果显示, 所有的NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂陶瓷的主相都呈现类钙钛矿结构, 介电性质随烧结温度变化很大。高于1020℃烧结的陶瓷的室温相对介电常数大于3000, 具有高介电性质。复阻抗谱显示, NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂陶瓷的电学分布不均匀, 由绝缘性的晶界和半导性的晶界组成。通过XRD和XPS测试发现, 在陶瓷中观察到了CuO第二相和Cu、Ti、Sb、Ta离子的变价。因此, 利用内阻挡层电容效应可以解释NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂陶瓷的高介电性质。

High Dielectric-permittivity Properties and Relevant Mechanism of NaCu3Ti3Sb0.5Nb0.5O12 Ceramics

A series of NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂ ceramics were prepared by conventional solid-state reaction technique at different sintering temperatures. Their crystalline structures, microstructures, dielectric properties and complex impedance were systematically investigated. All the ceramics show the main phase of perovskite-related crystallographic structure, and their dielectric properties change significantly with sintering temperature. Those ceramics sintered above 1020°C perform high dielectric-permittivity properties with ε' over 3000. Impedance spectroscopy analysis reveals that NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂ ceramics are electrically heterogeneous and composed of semiconducting grains and insulating grain boundaries. Moreover, a small amount of CuO secondary phase and Cu²⁺/Cu⁺, Ti⁴⁺/Ti³⁺, Sb⁵⁺/Sb³⁺ and Ta⁵⁺/Ta³⁺ aliovalences are found to exist in NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂ ceramics through XRD and XPS analysis. Internal barrier layer capacitance effect suggests the origin of the high dielectric-permittivity properties in NaCu₃Ti₃Sb_0.5Ta_0.5O₁₂ ceramics.