High magnetic-refrigeration performance of plate-shaped La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6) hydrides sintered in high-pressure H_2 atmosphere

摘要

La(Fe, Si)_(13) hydride is regarded as one of the most promising room-temperature refrigerants. However, to use the alloys in an active magnetic regenerator machine, it is vital to prepare thin refrigerants. In this work, a high H_2 gas pressure of 50 MPa was employed to suppress the desorption of hydrogen atoms during the sintering process of plate-shaped La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6) hydrides. At 330 K, a high-density sintered thin plate shows a large magnetic-entropy change ΔS_m of 15.5 J/kg K (106mJ/cm~3K) for a field change of 2T. The volumetric ΔS_m is almost twice as large as that of bonded La(Fe,Si)_(13) hydrides. Favorably, hysteresis is almost absent due to the existence of micro-pores with a porosity of 0.69% which has been analyzed with high-resolution X-ray microtomogra-phy.