Magneto-Caloric Properties Of New Rare Earth-Transition Metal Based Compound

Recently, room temperature magnetic refrigeration has attracted interest due to its high efficiency and environmental amity. As a result, many efforts have been put into the R&D of magneto-caloric materials. Nowadays, Gadolinium (Gd), whose Curie Temperature (TC) is around ambient temperature with a typical second order phase transition, was extensively used in related magnetic refrigeration technique due to its ideal magnetic entropy change (?S) under high magnetic field (H > 5T). However, its high price makes it difficult to serve in practical application. On the other hand, some novel compounds with first-order phase transition near room temperature, such as Gd5(SixGe1-x)4, MnFeP1-xAsx, La(FeSi)13 exhibit higher ?S, but their giant thermal and magnetic hysteresis are still major concern before application. The present study are therefore try to discovery some second order phase transition magneto-caloric materials with good properties in rare earth– transition based compounds, which are known for their excellent intrinsic magnetic properties.Alloys with nominal composition of Gd8(Fe0.9Mn0.1)92 and (Gd0.5Ce0.5)11(Fe0.9Mn0.1)89 were prepared by induction melting and long term annealing. XRD results show the alloys crystallize into TbCu7 structure with minor Gd-rich phase. SEM indicates the alloys were remarkably homogenized after annealing. VSM results show the TC of the alloys are 305 and 310K, respectively, and the maximum entropy change (?Smax) under 1.5 T are all -0.6 J/kg·K. In addition, the adiabatic change (?Tad) of the alloys under 1.5 T are 0.5 and 0.6K, respectively. After that, another batch of alloys8 of (Sm0.2Er0.2Pr0.5Ce0.1)12.2Fe87.8, (Sm0.3Er0.1Pr0.5Ce0.1)12.2Fe87.8, and (Sm0.3Pr0.5Ce0.2)12.2Fe87.8 were investigated. They all have Th2Ni17 structure and their TC are 305, 315, and 325K, respectively. The ?Smax of (Sm0.2Er0.2Pr0.5Ce0.1)12.2Fe87.8 and (Sm0.3Er0.1Pr0.5Ce0.1)12.2Fe87.8 under 1.5 T are -3.5J/kg·K and -1.0J/kg·K, respectively. The ?Tad of the alloys under 1.5 T at 315 K are 1.2, 1.2, 0.9 K, repecitively.