On the Electrical Properties of Some Iron‐Copper and Copper‐Manganese Ferrites

Abstract

Abstract The electrical conductivity and Seebeck coefficient of some iron‐copper and copper‐manganese ferrites are investigated. The electrical properties are found to be highly dependent on the preparation conditions and this is explained by the chemical reduction of the Cu 2+ ions above 900 °C. For the iron‐copper ferrites a mixed conduction mechanism is proposed. The n‐carriers are electrons on Fe 3+ levels and these are dominant in the slowly cooled samples. The p‐carriers are holes on oxygen ions, these being dominant in samples quenched from temperatures above 1120 °C. An irreversible increase of the Seebeck coefficient and resistivity is produced by heating the quenched samples in the temperature range 350 to 550 °C, and this is due to oxidation of the Cu 1+ ions.