通过拟合磁化强度函数计算磁熵变

Calculation of Magnetic Entropy Changes by Fitting Magnetization Function

用振动样品磁强计测量DyCo2化合物的磁化曲线,采用二元函数在矩形区域的双一次插值逼近拟合出M (T, H )的二元函数表达式,然后根据磁熵变的热力学公式,计算出它的磁熵变值。通过计算得到DyCo2合金的居里温度为142 K,在外磁场变化为1 T时,最大磁熵变为5.45 J/kg·K,因而DyCo2合金是良好的磁制冷材料。计算结果表明这种计算磁熵变的方法可行,能够得到比较准确的结果。

The DyCo2 compound-magnetic refrigeration materials for high temperature was prepared by arc-melting. The magnetization curves were measured by a vibrating sample magnetometer (VSM). The binary variable approximating function of M (T, H) was fitted by bilinear interpolation method of product form. The magnetic entropy changes(DeltaS(M)) as a function of the temperature(T) in magnetic field (1 T) for DyCo2 samples have been calculated. The results show that the Curie temperature and the maximum value of the magnetic entropy change in a field of 1 T of DyCo2 is 142 K and 5.45 J/kg (.) K respectively. This calculation provides a feasible and exact approach to find Curie temperature and the maximum value of the magnetic entropy change of the magnetic refrigerant material. This work can provide the preliminary information, which is necessary for the design of magnetic refrigerator.