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利用机械合金化和放电等离子烧结技术制备Mn1.2Fe0.8P0.76Ge0.24室温磁制冷材料。采用XRD、SEM分析烧结样品的相结构和显微组织,发现烧结样品显微组织均匀致密,但是存在少量MnO、Fe3Mn4Ge6杂质相。利用DSC测试样品的热流对温度的变化曲线,并计算出熵变随温度的变化关系。结果显示,Mn1.2Fe0.8P0.76Ge0.24的居里温度TC在–10℃左右,在–7℃的时磁熵变为23J/(kg·K)。
Mn1.2Fe0.8P0.76Ge0.24 room-temperature magnetic refrigeration materials were prepared by mechanical alloying and spark plasma sintering. The phase structure and microstructure of sintered samples were analyzed by XRD and SEM. The microstructure of sintered samples was found to be uniform and compact, but there were a few MnO and Fe3Mn4Ge6 impurity phases. The curves of heat flux versus temperature were measured by DSC, and the entropy change with temperature was calculated. The results show that the Curie temperature TC of Mn1.2Fe0.8P0.76Ge0.24 is about -10 ℃, and the magnetic entropy at 23 ℃ is 23J / (kg · K) at -7 ℃.