NaCu_3Ti_3NbO_(12)和NaCu_3Ti_3SbO_(12)陶瓷的巨介电性质及NaCu_3Ti_3SbO_(12)陶瓷的低介电损耗特性

Giant Dielectric-permittivity Property of NaCu_3Ti_3NbO_(12) and NaCu_3Ti_3SbO_(12) Ceramics and Low Dielectric Loss in NaCu_3Ti_3SbO_(12) Ceramics

利用传统的固相反应工艺制备了NaCu3Ti3NbO12和NaCu3Ti3SbO12陶瓷,对它们的介电性质和晶格结构进行了研究。结果显示,两种陶瓷都存在低频介电常数高于7×103的巨介电行为;在室温或者更低温度下,两种陶瓷的介电频谱(40 Hz^110 MHz)的实部只出现一个介电弛豫,而更高温度下的介电频谱的实部则会有两个介电弛豫;XRD结果显示两种陶瓷中都含有少量的CuO第二相。这些实验结果能用CCTO陶瓷中的内阻挡层电容效应解释。NaCu3Ti3SbO12陶瓷的室温介电损耗在40 Hz到7 kHz的宽频率范围内低于0.05,并且其1 kHz的介电损耗在-50~80℃的宽温度范围内低于0.05,这对于实际应用有重要意义。

NaCu3Ti3NbO12 and NaCu3Ti3SbO12 ceramics were prepared by the conventional solid state reaction method, and their dielectric properties and crystalline structure were investigated. It was found that they were quite similar with the CaCu3Ti4O12 ceramics, showing giant dielectric-permittivity properties with ε＇ larger than 7×103. Within the measuring frequency range of 40 Hz-100 MHz, a single dielectric relaxation with the characteristic frequency around 1 MHz was detected at room temperature or below whereas an additional one in low frequency region is also observed at high temperatures. Furthermore, the existence of CuO secondary phase was confirmed by X-ray diffraction. In general, the results can be explained by the similar mechanism of internal barrier layer capacitance effect which was formerly proposed for CaCu3Ti4O12 ceramics. Here, it is worthy pointing out that the tanδ of NaCu3Ti3SbO12 ceramics is lower than 0.05 in a large frequency range from 40 Hz to 7 kHz, and the tanδ at 1 kHz is lower than 0.05 in a large temperature range of -50℃ to 80℃ at 1 kHz, which is a desirable characteristic for practical applications.