Control of large magnetocaloric effects in metamagnetic La(Fe_xSi_(1-x))_(13) compounds by hydrogenation

摘要

To obtain large magnetocaloric effects (MCEs) due to the itinerant-electron metamagnetic (IEM) transition in La(Fe_xSi_(1-x))_(13), the Curie temperature T_C has been controlled by hydrogen absorption. In La(Fe_(0.88)Si_(0.012))_(13)H_y compounds, T_C = 195 K for y = 0.0 increases with increasing hydrogen concentration, resulting in T_C = 330 K for y = 1.6. Furthermore, the magnetic moment is also stabilized against temperature by hydrogen absorption. Since the IEM transition is preserved after hydrogenation, large MCEs of the magnetic entropy change DELTA S_m and the adiabatic temperature change DELTA T_(ad) have been observed around room temperature. A large value of DELTA T_(ad) has been confirmed by a direct measurement in adiabatic magnetic field change for the La(Fe_(0.88)Si_(0.012))_(13)H_y (y = 0.0 and 1.6). Consequently, the La(Fe_xSi_(1-x))_(13) compounds and their hydrides are promising as high-performance magnetic refrigerants working in a wide range of temperature covering room temperature in relatively low applying magnetic fields.