Structure analysis using XRD refinement for replacement of copper (Cu) with manganese (Mn) in NdMn2Si2 compound

Abstract

In magnetic materials, a change in the degrees of freedom of the spins induces thermal effects can be used in refrigeration technology. Simultaneous occurrence of changes in structure bring an effect on magnetocaloric effect (MCE) and thus influence the magnetic refrigeration operation. Structural and magnetic properties of NdMn2-xCuxSi2 compounds (x = 0 - 1.0) have been investigated by refinement of room temperature X-ray diffraction (XRD), DC magnetization, and differential scanning calorimetry measurements. Substitution of Cu for Mn leads to an increase in the lattice parameter a but a decrease in c at room temperature. Furthermore, increasing the Cu concentration in NdMn2-xCuxSi2 compounds lead to increase the secondary structure (impurity) as indicated the additional of peak in XRD measurement. Curie Temperature (TC) increases significantly with increasing Cu content from 36 K at x = 0 to 100 K at x = 1.0. Two magnetic phase transitions have been found in NdMn2-xCuxSi2 compounds refer to NdMn1.8Cu0.2Si2 compound as reference to Neel Temperature (TN) for the antiferromagnetic ordering of Mn-sublatttice and TC for the Nd-sublattice ferromagnetic ordering. The values of magnetic entropy change, –ΔSM around TC decrease from 27 J kg−1 K−1 for x = 0 to 1.5 J kg−1 K−1 for x = 1.0 under 0-5 T field with increasing of Cu concentration, respectively.