Magnetic refrigeration based on magnetocaloric effect at room temperature is generally considered a potential substitution for classical vapor compression systems due to its high efficiency and environmental friendliness. (MnNiSi)_1−x(Fe₂Ge)_x materials are attractive multicaloric materials that change their magnetic properties with the application of magnetic field, pressure, and temperature 1,2. The effects of electron and proton irradiation techniques in magnetocaloric materials have been reported in peer-reviewed articles therefore, this study investigated the effects of X-ray irradiation on (MnNiSi)_1−x(Fe₂Ge)_x.

Polycrystalline (MnNiSi)_1−x(Fe₂Ge)_x samples were prepared by arc-melting the constituent elements of purity better than 99.9% in an ultrahigh argon atmosphere to ensure sample homogeneity2. The procedure utilized X-RAD 225XL Precision X-Ray. The study evidences an observable effect in the (MnNiSi)_1-xFe₂Ge_x,x = 0.34 composition when exposed to an absorbed X-ray dosage of ~120Gy/min for 5 hours. A Quantum Design PPMS was used to measure the magnetization (M) of the (MnNiSi)_1−x(Fe₂Ge)_x with applied magnetic fields from -3T to 3T. Fig.1(a)shows the M-T data from 200K to 350K with T_c ~ 292K before treatment and 286K after treatment (cooling curve). There was also a significant change in the magnetization ~47.4% from 2.72 emu/g to 4.01 emu/g at an applied magnetic field=100Oe. Fig.1(b)presents the M-H (magnetization vs. magnetic field) loops from 300K to 345K as it exhibited irradiation-induced hysteresis in comparison to the pristine sample. Fig.2(a)exhibits an observable change of 10Oe in the magnetic coercivity at 200K after treatment. Fig.2(b)presents the hysteresis graphs for the samples at 200K and shows a saturation magnetization decrease but yielded an increase in magnetization from H=0Oe-4500Oe for the treated sample. These presented results would provide base guidelines for factors affecting the performance of magnetocaloric materials in extreme environments.