High-performance magnetic refrigerants based on itinerant-electron metamagnetic La(Fe_xSi_(1-x))_(13) compounds for room temperature cooling systems

摘要

Magnetic refrigerations are attractive for high environmental safety and high energy efficiency. Recently, we have developed new magnetic refrigerants based on La(Fe_xSi_(1-x))_(13) ( 0.86 <=x< =0.90 ) showing the itinerant-electron metamagnetic (IEM) transition, namely, the first-order phase transition from the paramagnetic to the ferromagnetic state in applied magnetic fields. These compounds have large magnetocaloric effects (MCEs) such as the isothermal magnetic entropy change triangle open S_m and the adiabatic temperature change triangle open T_(ad) in the vicinity of the Curie temperature T_C approx 190K. To extend the working temperature range, T_C of La(Fe_xSi_(1-x))_(13) was controlled by hydrogen absorption with keeping the IBM transition, resulting in a successive increase of T_C up to room temperature by changing hydrogen concentration.