【作者】 姜永静；

【导师】 李国栋；

【作者基本信息】 内蒙古大学 ， 凝聚态物理， 2004， 硕士

【摘要】 采用非自耗真空电弧炉熔炼制备了GdDyFe、GdDyFeNi、GdDyFeAl系列磁制冷材料。利用振动样品磁强计测量了各合金在低磁场（μ_oH=0.05T）下的M-T曲线，确定了合金的居里温度T_c。在居里温度附近测量了各合金在多组温度下的恒温磁化曲线，外场变化为0～1.5T，结合公式计算出材料的磁熵变。所得结果是：GdDyFe、GdDyFeNi、GdDyFeAl合金的最大磁熵变分别可达到3.94、3.5、3.76J／（kg·K）。合金的居里温度可在室温附近250～309K的范围内变化。从实用化方面考虑，此系列合金材料价格便宜，在较低磁场下有较大的磁熵变，制冷温度可在室温附近较宽的范围内变化，若考虑将此系列合金制成更为适合磁埃里克森循环的复合材料，此系列合金是可供选择的室温磁制冷材料。 对纳米磁制冷材料(Gd_0.73Dy_0.27)_0.925Fe_0.075和(Gd_0.73Dy_0.27)_0.925(Fe_0.5Ni_0.5)_0.075做了初步研究，与同等条件下的块材相比，纳米材料的居里温度分别下降了16K和14K，熵变值下降了1.37J／（kg·K）和1.19J／（kg·K）。经研究还发现，纳米材料的温熵曲线较块材平滑，是较块材更为适合磁埃里克森循环的室温磁制冷材料。纳米材料也可能成为良好的室温磁制冷工质。更多还原

【Abstract】 A series of magnetic refrigerant materials of GdDyFe,GdDyFeNi and GdDyFeAl were prepared with non-self consuming arc furnace. The M-T curve was measured in a field of 0.05T with a vibrating sample magnetometer to determine the Curie temperature. Choosing some temperatures near the Curie temperature, at every temperature the isothermal magnetization curve was measured in the field range of 0-1.5T. The magnetic entropy change can be calculated with the magnetization data and thermodynamical equilibrium equations. The maximum magnetic entropy change is 3.94 J/(kg ?K) for GdDyFe and 3.5J/(kg ?K) for GdDyFeNi and 3.76J/(kg ?K) for GdDyFeAl respectively. The Curie temperature of these alloys varied from 250K to 309K near room temperature. Considered the practicability, these alloys have comparatively large magnetic entropy change and low cost under a low field of 1.5T, their refrigerant temperature varied in a comparatively wide range, and we can consider using these alloys to make complex materials which are suitable for the Ericsson cycle. For the above-mentioned advantages, these alloys are suitable candidates as magnetic refrigerant materials near room temperature.We made a preliminary study on nanomaterials (Gdo.73Dyo.27)o.925Feo.o75 and (Gdo.73Dyo.27)o.925-(Feo.5Nio.5)o.o75- Compared with the respective bulk alloys, the Curie temperatures of nanomaterials reduced 16K and 14K, and the maximum magnetic entropy change reduced 1.37J/(kg ?K) and 1.19J/(kg ?K) respectively. The AS -T curves of the nanomaterials are smoother than that of the bulk materials, So nanomaterials are the magnetic refrigerant materials which are more suitable for the Ericsson cycle than the bulk materials. The nanomaterials may be good magnetic refrigerant materials in the future.更多还原