Study of the Magnetocaloric Effect in Ni1-xZnxFe2O4 Spinel

Nanoparticles Ni 1- x Zn x Fe 2 O 4 (0.4 ≤ x ≤ 0.7) samples were synthesized through co-precipitation method, and the effect of zinc concentration on the structural, magnetic, and magnetocaloric properties was investigated. X-ray diffraction patterns reveal the formation of single-phase spinel. The average crystallite size, estimated using Scherrer’s formula, was found to be ranging from 83 to 116.6 nm. The Curie temperature was found to decrease from 619 to 350 K with increasing x from 0.4 and 0.7. The Arrott plots reveal a second-order ferromagnetic transition in all samples. Magnetic entropy change (-Δ S m ) allowing estimation of the magnetocaloric effect was determined based on the thermodynamic Maxwell’s relation. The (-Δ S m ) was found to slightly increase with increasing x from 0.4 to 0.5 and decreasing with increasing x . The relative cooling power increases linearly with zinc content, up to x = 0.5.