Effect Cr sup(3+) ion substitution on the structural, magnetic, and dielectric behavior of Co-Cu ferrite

Abstract

Cr sup(3+) substituted cobalt-copper ferrites with chemical composition Co sub(0.9)Cu sub(0.1)Fe sub(2-x)Cr sub(x)O sub(4) (where x = 0.00, 0.03, 0.06, 0.09, 0.12, and 0.15) were prepared by sol-gel mediated auto combustion route utilizing malic acid as a complexing agent. The effect of incorporation of Cr sup(3+) ions in low concentration on the structural, magnetic, dielectric, and electrical features of the Co-Cu ferrite compounds was investigated. The crystalline nature and variation in crystallite size with substituent content were identified from X-ray diffraction. Cr sup(3+) substitution for Fe in the Co-Cu ferrite leads to a monotonic decrease in the saturation magnetization at 300 K as well as at 50 K, which could be credited to the decrease in strength of superexchange interaction on the substitution of Fe sup(3+) ions by weakly magnetic Cr sup(3+) ions in the octahedral site. Substitution of small fractions Cr sup(3+) ions for some of the Fe in cobalt-copper ferrites decreased the Curie temperature. A decreasing pattern in DC resistivity with an increase in temperature was observed ensuring the semiconducting character of the ferrites under test. Dielectric properties such as dielectric constant (epsilon') and dielectric loss (tan delta) of prepared materials were investigated.