Effect of interstitial boron and hydrogenation on the magnetocaloric properties of La0.8Ce0.2Fe11.4Si1.6 compound

Abstract

This study explores how boron doping influences hydrogen absorption and magnetocaloric properties in the La0.8Ce0.2Fe11.4Si1.6 (LCFS) compound. While hydrogenation can adjust the Curie temperature (TC) in magnetocaloric materials, its influence on hysteresis loss remains a challenge. To address this, we synthesized a series of hydride La0.8Ce0.2Fe11.4Si1.6BxHy compounds by exposure to the La0.8Ce0.2Fe11.4Si1.6Bx (LCFSB) alloys and analyzed their structure. X-ray diffraction confirmed phase composition, revealing that boron and hydrogen co-doping tunes TC between 174 and 329 K. The addition of boron and hydrogen significantly diminished the itinerant electron metamagnetic (IEM) transition and increased the slope of the critical field, HC, while reducing magnetic hysteresis. This preserves a high maximum entropy change, ΔSM with maximum values of 21.8, 12.6, and 12.1 kg−1 K−1 under 0–5 T for different compositions. The corresponding effective refrigerant capacity, RCPeff values are 121.3, 154 and 81.2 J kg−1 respectively. It was found that the inclusion of boron in the LCFS compound enhanced the absorption of hydrogen. Further, the evaluation of dehydrogenation dynamics revealed that the B doping significantly enhanced the stability of hydrogen and the stable temperature was increased to 250 °C for B doped samples. Finally, these findings demonstrate that boron doping optimizes hydrogen absorption, improves thermal stability, and enhances magnetocaloric performance by mitigating hysteresis losses.