The giant dielectric constant and tunable properties of La2NiMnO6–xMgO ceramics

• Published in: Journal of alloys and compounds Vol. 616; pp. 213 - 220
• Main Authors: Chen, Hao, Cao, Zhenzhu, Wang, Liying, He, Weiyan, Sun, Junmin, Zhang, Yongfeng, Ruan, Xuezheng
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.12.2014; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric loss and relaxation; Dielectric properties; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Extrinsic contribution; Permittivity (dielectric function); Physics; Tunability; Extrinsic contribution; Dielectric properties; Tunability; Grain boundaries; Grain growth; Magnesium oxide; Tuning; Dielectric relaxation; Dielectric losses; Solubility limit; Microstructure; Permittivity; Manganites
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.07.119

•The extrinsic origins of giant dielectric constant and tunability have been revealed.•Electrode effect results in giant permittivity and tunability.•The addition of MgO increases tunability around room temperature. Effect of MgO addition on the microstructure, electrical and dielectric properties of La2NiMnO6 ceramics was investigated. Trace amount of Mg2+ substituted Ni ion. After exceeding the limit of solubility, MgO segregated as an independent phase on the grain boundary and suppressed grain growth. Electrode response dominated impedance of La2NiMnO6–xMgO ceramics around room temperature. Two dielectric relaxations originated from electrode and grain boundary effects have been revealed, which resulted in the giant dielectric constant of La2NiMnO6–xMgO ceramics. The addition of MgO suppressed dielectric constant and loss. The electrode effect caused the sizable dielectric tunability at high temperature and low frequency range. The addition of MgO increased electrode response of La2NiMnO6–xMgO around room temperature and enhanced the tunability.