Magnetocaloric effect in reactively-milled LaFe11.57Si1.43Hy intermetallic compounds

Hydrides of LaFe11.57Si1.43 intermetallic compound have been prepared by high-energy ball milling in the presence of hydrogen gas, a process known as reactive milling. The Curie temperature of the samples was tuned within the temperature range of 199 K to 346 K by changing the hydrogen content from 0 to 2.3 at. % without compromising much of the magnitude of the magnetocaloric effect. Arrott plots and large hysteresis in the magnetization vs magnetic field curves confirm that the first-order itinerant-electron metamagnetic transition is the reason for large entropy change in the parent as well as in the hydride samples. The present study indicates that reactive milling can be an effective method for incorporating interstitial hydrogen within these compounds in order to raise their TC to room temperature.