Oxygen vacancies doping effect on the electrical and magnetic behavior of Ba5-xLaxNb4-xTixO15

J. M. DE PAOLI

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS

Elsevier Ltd.

Año: 2007 vol. 68 p. 124 - 124

0022-3697

e report electric and magnetic properties of oxygen deficient Ba5−xLaxNb4−xTixO15−δ phases, which have been prepared by solid-state reaction method followed by a controlled reduction process under hydrogen atmosphere. The extra electrons added by the formation of the oxygen vacancies (δ) introduce localized spins and the magnetic susceptibility can be described by a temperature-independent contribution and a Curie?Weiss term associated to the Ti3+ ion formation. Besides, the experimental resistivity (ρ) data of these four reduced compounds are well described in a wide temperature range with the equation ρ= AT exp(B/T)^(-1/4) , which suggests the presence of small polarons in the system. Although, all samples present electrical insulating behavior, the electrical resistivity decreases four orders of magnitude for intermediate x values. We interpreted this fact as a consequence of the mix between the localized bands of the Nb and Ti ions, which favo