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Günther, A.; Hochleitner, R.; Lohringer, H.; Schmidbauer, E.; Schoettler-Himmel, A.; Volk, M. (2017): Low-temperature electrical and dielectric properties and Mossbauer spectra of rutile-type FeNbTiO6, prepared in oxidizing and reducing conditions. In: Journal of Physics and Chemistry of Solids, Vol. 111: pp. 274-285
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Abstract

In this communication we present preferentially bulk electrical and dielectric quantities on rutile-type FeNbTiO6 samples below room temperature (RT), sintered in air, CO2 or 5%H-2/CO2 atmosphere between temperatures of 1423 K and 1573 K. In the past, FeNbTiO6 had been found to exhibit relaxor ferroelectric-like dielectric constant peaks at 500-600 K, assigned to bulk properties and to some extent to grain boundary and sample-electrode processes. Below RT, mainly bulk data were collected from impedance spectra;derived quantities describe characteristic features of bulk response for samples prepared in different conditions. The DC electrical conductivity obeys Mott's variable range T-1/4 law between approximate to 80 K and 220 K for samples sintered at 1573 K in air, as already reported previously, while after heating at 1473 K in air, Arrhenius behavior occurs. The individual samples show characteristic differences as regards DC and AC conductivity, dielectric constant and dissipation factor tans. Fe-57 Mossbauer spectroscopy enabled to gain knowledge of local inhomogeneities in the environment of FeO6 octahedra that may affect electrical conduction. This concerns in particular samples, prepared in reducing conditions of H-2/CO2 atmosphere, with Fe2+ exceeding by far the fraction of Fe3+.