Mn2-xFexP1-yGey（x=0.8、0.9,y=0.2、0.24、0.26）磁制冷材料的制备工艺及磁热性能研究

摘要

Mn2-xFexP1-yGey(x=0.8,0.9,y=0.2,0.24,0.26)magneto-caloric compounds have been prepared by mechanical alloying (MA)and subsequent spark plasma sintering (SPS)technique.XRD,neutron diffrac-tion and SEM were used to analysis the influences of the ball milling time,sintering temperature,pressure and time on the phase formation systematically.A stable preparation technique for the MnFePGe magneto-caloric materials was established.It was found that the quantity of the impurity decreased as the temperature increas-ing.The magnetic phase transition process and magnetocaloric properties of the Mn2-x Fex P1-y Gey alloys were investigated by DSC and SQUID.The compound Mn1.2 Fe0.8 P0.74 Ge0.26 was expected to be a suitable candidate for a magnetic refrigeration applications with a small thermal hysteresis (3K),a Curie temperature close to room temperature (277.4K),and a large magnetocaloric effect (ΔSDSC=21.5J/(kg·K).%利用机械合金化和放电等离子烧结技术制备了Mn2-xFexP1-yGey(x=0.8、0.9,y=0.2、0.24、0.26)磁制冷材料。采用XRD、中子衍射及 SEM分析手段,系统研究了该系列材料的成相与球磨时间、烧结温度、烧结压力和保温时间的关系。分析了烧结样品的相结构和显微组织,发现随着烧结温度的升高杂质相逐渐减少,形成了稳定的该系列磁制冷材料的制备工艺。对不同组分 Mn2-x Fex P1-y Gey 合金的相变过程和磁热性能进行了分析,其中 Mn1.2 Fe0.8 P0.74 Ge0.26的居里温度为277.4K 接近于室温区间,滞后为3K、熵变为21.5J/(kg·K),是一种较理想的磁制冷工质材料。