DC conductivity in barium hexaferrites doped with bismuth oxide

Pal, M. ; Brahma, P. ; Chakraborty, B. R. ; Chakravorty, D. (1997) DC conductivity in barium hexaferrites doped with bismuth oxide Japanese Journal of Applied Physics, 36 . pp. 2163-2166. ISSN 0021-4922

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Official URL: http://jjap.jsap.jp/cgi-bin/getarticle?magazine=JJ...

Related URL: http://dx.doi.org/10.1143/JJAP.36.2163


Barium hexaferrites of compositions BaO·(6-x)Fe2O3·xBi2O3 with 0 \leqslantx \leqslant0.4 have been synthesized by the ceramic calcination route. The bismuth substituted hexaferrites exhibit dc electrical conductivities more than two orders of magnitude higher than the pure ones. This is believed to arise due to an increase in the concentration of Fe2+ ions as a result of the presence of Bi5+ ions in these compounds. The dc conductivity at temperatures higher than 250 K can be explained on the basis of a non-adiabatic hopping model of small polarons, the variable valence iron ions forming the polaronic sites. At temperatures lower than 220 K a variable range hopping mechanism appears to control the conductivity.

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