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Colossal dielectric behavior of semiconducting $Sr_{2}TiMnO_{6}$ ceramics

Meher, Preethi KRS and Varma, KBR (2009) Colossal dielectric behavior of semiconducting $Sr_{2}TiMnO_{6}$ ceramics. In: Journal Of Applied Physics, 105 (3).

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Manganitelike double perovskite Sr2TiMnO6 (STMO) ceramics fabricated from the powders synthesized via the solid-state reaction route, exhibited dielectric constants as high as similar to 10(5) in the low frequency range (100 Hz-10 kHz) at room temperature. The Maxwell-Wagner type of relaxation mechanism was found to be more appropriate to rationalize such high dielectric constant values akin to that observed in materials such as KxTiyNi(1-x-y)O and CaCu3Ti4O12. The dielectric measurements carried out on the samples with different thicknesses and electrode materials reflected the influence of extrinsic effects. The impedance studies (100 Hz-10 MHz) in the 180-300 K temperature range revealed the presence of two dielectric relaxations corresponding to the grain boundary and the electrode. The dielectric response of the grain boundary was found to be weakly dependent on the dc bias field (up to 11 V/cm). However, owing to the electrode polarization, the applied ac/dc field had significant effect on the low frequency dielectric response. At low temperatures (100-180 K), the dc conductivity of STMO followed a variable range hopping behavior. Above 180 K, it followed the Arrhenius behavior because of the thermally activated conduction process. The bulk conductivity relaxation owing to the localized hopping of charge carriers obeyed the typical universal dielectric response.

Item Type: Journal Article
Publication: Journal Of Applied Physics
Publisher: American Institute of Physics
Additional Information: Copyright of this article belongs to American Institute of Physics.
Keywords: ceramics;dielectric polarisation;dielectric relaxation;electrical conductivity;grain boundaries;hopping conduction;permittivity;powders; semiconductor materials;strontium compounds;titanium compounds
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 30 Apr 2009 03:31
Last Modified: 19 Sep 2010 05:29
URI: http://eprints.iisc.ac.in/id/eprint/19583

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