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Turkish Journal of Physics

Thermoelectric Power in Ti^{4+} and Zr^{4+} Substituted Li-Zn Ferrites

Abstract

Thermoelectric power measurements have been reported for the system Li_{0. 5} Ti_{x}Zn_{x}Fe_{2.5-2x},O_{4}, where x=0, 0.1, 0.2 and 0.3, from room temperature to 700^{\circ}K. All the compositions exhibit n-type conduction. The composition with x=0.3 initially exhibits n-type conductivity whereas for the temperatures above 130^{\circ}C it exhibits p-type conduction. In the present system Zn^{2+} occupies A-site while Ti^{4+} occupies B-site (and works as donor). This is so because Fe^{3+} ions are being replaced by Zn^{2+} and Ti^{4+}. The band gap of the ferrite is thus expected to increase on the substitution of Zn, Ti. The conduction phenomenon is due to hopping process as n-type behaviour indicates that the hopping activation energy is possibly lower for donors (Ti^{4+}) which occupy B-sites. This is because the ionic radii of Fe^{3+} ions on B-sites is larger than those on A-sites assuming that high spin Fe^{3+} ions are present in the system.

DOI

-

First Page

757

Last Page

766

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