确定磁性体在绝热磁化过程中达到最高温度的方法

摘要

Determining the highest temperature attained by a magnetic material in the adiabatic magnetization is important for the optimal selecting of magnetocaloric material. As an example, the Gd3Ga5O12 crystals are investigated. Under the superstrong magnetic field and at low temperature, the form of effective magnetic susceptibility is given based on the tendency-saturation law. The magnetic entropy change and the phonon entropy change as well as the magnetocaloric effect are calculated in a magnetic field range from 0 to 40 T. The calculated results are in good agreement with the measured data. A method of determining the highest temperature attained by magnetic material in the adiabatic magnetization is given by using the only intersection point between the curves of the saturationmagnetic entropy change and the phonon entropy change. The highest temperature in the adiabatic magnetization is predicted to be 64.7 K for the Gd3GasO12 crstal.%在磁性体磁化过程中,决定其能够达到的最高温度,对磁热材料的优化选取是重要的.本文以钆镓石榴石（Gd3Ga5O（12））为例,根据高磁场下趋近饱和定律的思想,给出了低温、超强磁场下,Gd3Ga5O（12）晶体等效磁化率的定量形式.在外磁场从0—40T范围内,计算了该晶体的磁熵变、声子熵变以及磁性体温度随外磁场的变化,结果均与实验值符合较好.利用声子熵变与饱和磁熵变曲线交点的唯一性,给岀了在磁性体磁化过程中,确定其温度达到最大值的方法,预言了Gd3Ga5O（12）晶体在绝热磁化过程中达到的最高温度为64.7K.该方法还可以对所加外磁场大小进行预言或估计.