Electrical resistivity, thermopower, and Fe57 Mossbauer study of FeNbO4
Schmidbauer, E., and J. Schneider (1997),
Electrical resistivity, thermopower, and Fe57 Mossbauer study of FeNbO4,
Journal of Solid State Chemistry, 134(2), 253264.
 Abstract
 The electrical charge transport was investigated an sintered semiconducting FeNbO4 and compositions with a slight surplus of Nb in the monoclinic (pseudorhombic) wolframite and orthorhombic alphaPbO2 structures using electrical DC, AC resistivity (complex plane impedance analysis), and thermopower Theta in the temperature T range approximate to 100900 It. At low T, the experimental crystallite conductivity sigma is consistent with a variablerange hopping charge transport model, characterized by the relationship ln sigma proportional to T1/4. In the highT region, activation energies EA for the extrapolated crystallite DC resistivity are found up to EA approximate to 0.7 eV. The thermopower Theta is negative, with \Theta\ increasing with rising T in the lowT region, and between approximate to 120 and 300 K the data can be approximately described by a linear ThetaT1/2 relation for both structures that is theoretically predicted for variablerange hopping. Above 300 K, the curves bend and Theta becomes constant with values Theta similar to 270 and 220 to 230 mu V/g. Suggesting electron hopping Fe2+ > Fe3 to be the dominating charge transport mechanism, the Theta highT data are in part compatible with the assumption that all or a dominant fraction of Fe2+ and Fe3+ are taking part in this process; this result follows from the derived concentration ratio [Fe2+]/[Fe3+], which is similar to that determined from Fe57 Mossbauer spectra at 79 K. (C) 1997 Academic Press.
 BibTeX

@article{id220,
author = {E. Schmidbauer and J. Schneider},
journal = {Journal of Solid State Chemistry},
number = {2},
pages = {253264},
title = {{Electrical resistivity, thermopower, and Fe57 Mossbauer study of FeNbO4}},
volume = {134},
year = {1997},
language = {en},
}
 EndNote

%0 Journal Article
%A Schmidbauer, E.
%A Schneider, J.
%D 1997
%N 2
%V 134
%J Journal of Solid State Chemistry
%P 253264
%T Electrical resistivity, thermopower, and Fe57 Mossbauer study of FeNbO4