Electrical and magnetic properties of zinc-nickel manganites

Abstract

A series of compounds of the general formula ZnNi_xMn_2-xO₄ which contain both Mn³⁺ and Mn⁴⁺ ions at the octahedral sites have been synthesized and their structural, electrical and magnetic properties have been studied. The compounds in which x ≤ 0.3 are found to be tetragonal while those in which x ≥ 0.5 are cubic. The electrical properties indicate that the electrical conduction takes place by the hopping mechanism and thermoelectric coefficient measurements show that the compounds in which x ≤ 0.3 are p-type while those with x ≥ 0.5 are n-type. The compound with x=0.5 is however p-type below 200° C and n-type above this temperature. The plots of reciprocal magnetic susceptibility vs. temperature for all these compounds show a pronounced decrease in 1/χ M values below about 100° K, similar to ferrimagnetic compounds.