A Comparative Study of the Magnetocaloric Effect in MnFePSiGeB Prepared by Traditional Sintering and Spark Plasma Sintering

摘要

Two compounds with the same composition of Mn1.15Fe0.85P0.65Si0.13Ge0.2B0.02 have been synthesized by traditional sintering (TS) and spark plasma sintering (SPS) methods. A comparative study on the structural and magnetic properties of the compounds has been carried out using X-ray diffraction (XRD), scanning electron microscopy, and magnetic measurements. The XRD results reveal that both compounds crystallized mainly in the Fe2P-type hexagonal structure. The TS-prepared sample exhibits large holes and worse densification due to the evaporation of P, when comparing with the SPS-prepared sample. The Curie temperatures are found to be 251 and 291 K on cooling, and 261 and 298 K on heating for the compounds prepared by SPS and TS, respectively. For a field change of 3 T, the maximum values of isothermal entropy changes are found to be 15.1 and 7.9 J/kgK for the compounds prepared by SPS and TS, respectively. These results are correlated with the practical concentration of P in the compounds. This paper indicates that the SPS technique is suitable for synthesizing the Fe2P-type bulks with good magnetocaloric properties.