Giant dielectric response and mixed-valent structure in the layered-ordered double-perovskite ceramics

• Published in: Ceramics international Vol. 37; no. 7; pp. 2747 - 2753
• Main Authors: Yang, W.Z., Fu, M.S., Liu, X.Q., Zhu, H.Y., Chen, X.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2011
• Subjects: Activated; B. X-ray method; C. Dielectric properties; Ceramics; D. Perovskites; Dielectric relaxation; Dielectrics; Electrical conduction; Mixed-valent structure; Origins; Resistivity; Temperature dependence; Mixed-valent structure; C. Dielectric properties; B. X-ray method; D. Perovskites
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2011.04.029

Origin of giant dielectric response in the layered-ordered double-perovskite La 2CuSnO 6 ceramics was investigated in the present work. Apart from the main layered-ordered double-perovskite La 2CuSnO 6 phase, minor La 2Sn 2O 7 secondary phase was detected. There were two dielectric relaxations in the curve of temperature dependence of dielectric properties of La 2CuSnO 6 ceramics. Both of dielectric relaxations were thermal activated process. The low temperature relaxation should be attributed to the mixed-valent structure (Cu 2+/Cu 3+) since the activation energy was similar to that of La 2CuTiO 6 ceramics. While the high temperature relaxation was closely related to the thermal activated hopping process of electrical conduction. After annealing the sample in N 2 and O 2 atmosphere, the trend of dielectric behaviors and ac conductivities were the same at high temperature. This result confirmed that the high temperature relaxation was closely related to the electrical conduction.