Microwave Dielectric Properties of Ca_1+xCu₃Ti₄O_12+x (-0.04 ≿x ≿0.04) Ceramics

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• 作者：Mohamad Johari Abu^a ; Mohd Fariz Ab Rahman^a ; Rosyaini Afindi Zaman^a ; Mohsen Ahmadipour^a ; Julie Juliewatty Mohamed^b ; Mohd Fadzil Ain^c ; Zainal Arifin Ahmad^a ;
• 关键词：CaCu3Ti4O12 ; nonstoichiometry ; solid-state reaction ; microwave dielectric properties
• 刊名：Procedia Chemistry
• 出版年：2016
• 出版时间：2016
• 年：2016
• 卷：19
• 期：Complete
• 页码：929-934
• 全文大小：685 K

文摘

Ca_1+xCu₃Ti₄O_12+x (-0.04 ≤ x ≤ 0.04) ceramics were prepared by using conventional solid-state route. The microwave dielectric properties of the samples were investigated as a function of measured frequency and the Ca content. A pure perovskite structure was obtained for samples with -0.02 ≤ x ≤ 0.02, whereas small amount of CuO and CaTiO₃ appeared in the samples with x = -0.04 and 0.04, respectively, indicated that the solubility limit of Ca atom in CCTO lattice was reached for this system. Adjusting of Ca content showed a little influence on the microstructure of the ceramics. The sample with x = 0 exhibited good microwave dielectric permittivity (ɛ’ ∼ 85), which nearly constant at a broad frequency range of 1 – 35 GHz, then abruptly dropped to ∼70 at 50 GHz. The other samples showed a strongly frequency dependence of dielectric permittivity from ∼100 (at 1 GHz) to ∼10 (at 50 GHz). The dielectric loss (tan-δ) for nonstoichiometry CCTO samples is relatively higher at least an order of magnitude and displays strong frequency dependence as compared with the x = 0 sample. The existence of vacancy (oxygen and Ca) and Ca/Cu disorder are the main factor affecting ɛ’ and tan-δ values of the ceramics.