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Dielectric and Magnetodielectric Properties of R 2 NiMnO 6 (R = Nd , Eu , Gd , Dy , and Y )
Author(s) -
Kakarla Devi Chandrasekhar,
Jyothinagaram Krishna Murthy,
Das Amal Kumar,
Adyam Venimadhav
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13039
Subject(s) - dielectric , curie temperature , condensed matter physics , materials science , electrical resistivity and conductivity , analytical chemistry (journal) , magnetoresistance , chemistry , nuclear magnetic resonance , ferromagnetism , magnetic field , physics , optoelectronics , chromatography , quantum mechanics
We have prepared polycrystalline R 2 NiMnO 6 (R = Nd , Eu , Gd , Dy , and Y ) samples by conventional solid‐state reaction and all the samples have shown monoclinic structure with P 2 1 / n space group. With the decrease in rare‐earth ionic size (< r R >), the bond angle decreases, correspondingly a decrease in ferromagnetic (FM) Curie temperature is noticed. In the dielectric measurement, the dielectric anomaly shifts to high temperature with the decrease in the < r R > and shows no correlation with the FM Curie temperature and hints the absence of apparent magnetodielectric (MD) coupling. Appearance of multiple relaxations in the dielectric study suggests the electrical heterogeneity of the system. The dielectric/impedance analysis has revealed a close correlation between dc conductivity and the dielectrics; in fact, both dc resistivity and the grain relaxations follow the variable range hopping mechanism. The thermal activation of charge carriers at the grain boundary led to Maxwell–Wagner interfacial polarization. Finally, dielectric study under magnetic field showed no effect, it implies that not only the intrinsic MD is absent, but also the extrinsic MD due to the lack of magnetoresistance.