Near room temperature magnetocaloric effect of Cr1-xRuxO2 (x=0.000, 0.125, and 0.250) for magnetic refrigeration

In this scientific paper, we thoroughly investigated the magnetocaloric effect of Cr1-xRuxO2 (x = 0.000, 0.125, and 0.250) nanoparticles near room temperature. X-ray diffraction (XRD) is used to analyse the structure results. The magnetization versus temperature curves display a second-order magnetic phase transition from ferromagnetic (FM) to paramagnetic (PM) at 390, 302, and 286 K for x = 0.000, 0.125, and 0.250, respectively. The substitution of Cr by Ru leads to a decrease in TC from 390 to 286 K with an increasing concentration of ruthenium from 0.000 to 0.250. From the Curie-Weiss (CW) law, we have extracted the CW temperature (theta(P)) and the experimental effective magnetic moment (mu(exp)(eff )). In addition, these nanoparticles exhibit a large magnetic entropy change, which is advantageous to improve the relative cooling power (RCP). Under a magnetic field of 1.5 T, the RCP of Cr(0.875)Ru(0.125)O(2 )nanoparticles is found to be 324.35 J kg(-1) at T-C = 302 K which is superior to pure Gd at T-C = 293 K. From heat capacity measurements, the adiabatic temperature change (delta T-ad) is found to be 2.1 K for a magnetic field of 1.5 T. Consequently, a large magnetocaloric effect was observed in magnetic oxides. These magnetic oxide nanoparticles can be subject to magnetocaloric effect studies around the room temperature.