Structural, magnetic and magnetocaloric properties of nickel-copper ferrite with chromium substitution

Abstract

The structural, magnetic and magnetocaloric properties of Ni0.6Cu0.4Fe1.5Cr0.5O4 sample have
been investigated. The sample was synthesized by sol-gel method. The X-ray diffraction result indicates
that the ferrite sample has a cubic spinel type structure (Fd3̅m space group). Magnetization versus
temperature showed that sample exhibits a second-order paramagnetic (PM) -ferromagnetic (FM) phase
transitions with Curie temperature TC equal to 660 K. Magnetocaloric properties were obtained by
measuring a family of M(H, T) curves near TC and calculating both magnetic entropy change (ΔSM) and
relative cooling power (RCP). The magnetic entropy change reaches a maximum value |∆SM
max| of about

1.39 J.K-1
.kg
-1
for μ0H= 5 T corresponding to relative cooling power (RCP) of 142 J.kg-1

. These values are
comparable to that of some other ferrite materials considered as possible candidates for magnetic
refrigeration.