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Influence of Fabrication Parameters on the Phase Formation and Dielectric Properties of CaCu_3Ti_4O_(12 )Ceramics

查看全文 作　　者：Qian [1]Zheng;Huiqing [1]Fan 高影响力作者 机构地区：[1]State Key Laboratory of Solidification Processing,School of Materials Science and Engineering,Northwestern Polytech-nical University,Xi'an 710072,China高影响力机构 出　　处：《Journal of Materials Science & Technology》索引2012年第28卷第10期,共7页高影响力期刊 基　　金：financially supported by the National Natural Science Foundation of China (No. 51172187);the SRPDF (No. 20116102130002);the 111 Program of MOE(No. B08040);the Xi an Science and Technology Foundation of China (Nos. CX1261-2, CX1261-3 and XA-AM-201003) 摘　　要：The giant dielectric permittivity materials CaCu 3 Ti 4 O 12(CCTO) were synthesized by conventional solid-state reaction techniques.X-ray diffraction and Raman scattering for the powder indicate that the powder calcined at 950 C for 12 h has been completely transformed into the purer CCTO phase.Furthermore,the morphology and size of the grains of the ceramics sintered at 1090 C in the dwell time range from 0 to 26 h were observed by scanning electron microscopy(SEM).Dielectric properties of the polycrystalline CCTO ceramics were characterized in a broad frequency range(100 Hz-1 MHz) and at a temperature ranged from 300 to 500 K.The longer sintering time may lead to more defect structures and the enhanced conductivity,also leads to substantial improvements in permittivity.Grain size and density differences were not large enough to account for the enhancement in dielectric permittivity.Based on the observations,it is believed that the primary factor affecting dielectric behavior is the development of internal defects.The CCTO ceramics sintered at 1090 C for 15 h exhibit lower dielectric loss(~0.05) near room temperature,and the dielectric relaxation behavior above 1 kHz was observed to follow the Arrhenius law.The activation energy(E a) of 0.65 eV indicates that the doubly ionized oxygen vacancies in the grain boundaries are responsible for the dielectric relaxation of the CCTO ceramics. 关 键 词：介电性能 陶瓷 工艺参数 ARRHENIUS 高介电常数 扫描电子显微镜 X-射线衍射 烧结时间
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