Role of doping and CuO segregation in improving the giant permittivity of CaCU3Ti4O12

被引：210
作者：
Capsoni, D
Bini, M
Massarotti, V
Chiodelli, G
Mozzati, MC
Azzoni, CB
机构：
[1] Univ Pavia, Dipartimento Chim Fis M Rolla, I-27100 Pavia, Italy
[2] IENI, CNR, Sez Pavia, I-27100 Pavia, Italy
[3] Univ Pavia, Dipartimento Fis A Volta, INFM, I-27100 Pavia, Italy
来源：
JOURNAL OF SOLID STATE CHEMISTRY | 2004年 / 177卷 / 12期
关键词：
CaCu3Ti4O12; cation doping; EPR; defect models; impedance spectroscopy; conductivity measurements; grain boundary; giant permittivity; diffraction profile refinement;
D O I：
10.1016/j.jssc.2004.09.009
中图分类号：
O61 [无机化学];
学科分类号：
070301 ; 081704 ;
摘要：
The dopant role on the electric and dielectric properties of the perovskite-type CaCu3Ti4O12 (CCTO) compound is evidenced. Impedance spectroscopy measurements show that the relevant permittivity value attributed to sintered CCTO is due to grain boundary (g.b.) effects. The g.b. permittivity value of the pure CCTO can be increased of 1-2 orders of magnitude by cation substitution on Ti site and/or segregation of CuO phase, while the bulk permittivity keeps values 90 < epsilon(r) < 180. Bulk and g.b. conductivity contributions are discussed: electrons are responsible for the charge transport and a mean bulk activation energy of 0.07 eV is obtained at room temperature for all the examined samples. The g.b. activation energy ranges between 0.54 and 0.76 eV. Defect models related to the transport properties are proposed, supported by electron paramagnetic resonance measurements. (C) 2004 Elsevier Inc. All rights reserved.
引用
收藏
页码：4494 / 4500
页数：7
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