【摘要】 通过研究在不同气氛(氮气和氧气),Ca-Cu3Ti4O12(CCTO)陶瓷样品在一定温度下进行后处理后,不同功函数电极对其介电性质的影响,进而研究CCTO陶瓷的巨介电常数的起源问题。我们在空气中制备了CaCu3Ti4O12陶瓷,发现样品表面电阻率很大,样品表面呈现绝缘态,此时不同功函数电极以及不同电极制备方法对其介电性质几乎没有影响,说明CC-TO的巨介电常数是由孪晶界或半导体晶粒与绝缘晶界所产生的内部阻挡电容(IBLC)所引起。但当样品在高温氮气中后处理后,样品表面电阻率明显下降,以较大功函数的金属作为电极的样品,其介电常数有了明显的提高,而以功函数小的金属作为电极的样品,其介电常数变化不大。从而进一步说明当CCTO样品表面处于半导态,表面电极效应也是CCTO巨介电常数来源之一。更多还原

【Abstract】 The effects of the different post-annealing atmosphere and the metal electrodes on the dielectric properties of the CaCu₃Ti₄O₁₂（CCTO） ceramic were studied in the paper,in order to clarify whether the surface contact is responsible for the giant dielectric constant of CCTO.The CCTO ceramic were fabricated by a common solid-state reaction in the air.The as-prepared sample is insulating and its dielectric property is insensitive to the metal electrodes with different energy of work functions,indicating the intrinsic nature is related to the giant dielectric constant of CCTO.However,after the sample was subjected to a nitrogen atmosphere at 750℃ for 8h,the surface resistivity of CCTO becomes one-order lower,and its dielectric property becomes sensitive to the metal electrodes.The sample with Pt electrode shows a significant increase of dielectric constant within the frequency range of 100Hz～1MHz.Obviously,in this case,the external contacts via an interfacial polarization process contribute partly to the high dielectric constant of CCTO.更多还原