Er_(2-x)Pr_xFe_(17)化合物的结构与磁熵变

Structure and Magnetic Entropy Change ofEr_(2-x)Pr_xFe_(17)Compounds

较详细地研究了Er2-xCexFe17化合物的结构、磁性和磁熵变.结果表明,轻稀土Ce的掺入虽然没有明显改变Er2Fe17化合物的相结构及其晶格常数,但改变了Er次晶格与Fe次晶格之间的耦合系数,使仍为Th2Ni17型六方结构的Er2-xCexFe17化合物的居里温度可通过成分微调使其处在室温附近.Er2-xCexFe17化合物的λ形(-△SM)-T曲线表明其在居里点附近发生的相变属于二级相变,它使化合物可在较宽温区范围内保持较大的磁熵变.Er2-xCexFe17化合物在x=0.05～0.1范围内具有较大的磁熵变,其在2.0 T和5.0 T外场下的最大磁熵变达到金属Gd的40%～50%,且其化学性质稳定、制冷温区宽、价格低廉,是一类性价比较高、应用潜力较大的新型低场室温磁制冷工质材料.

The structure and the magnetic entropy change of Er2-xCexFe17 compounds have been studied in detail in this paper. The results show that the even crystal structure of the compounds is yet the Th2Ni17-type hexagonal by Ce substituting for Er in Er2Fe17 intermetallic, the exchange coupling coefficients have been changed between the Er and Fe sublattices, which results in the Curie temperature of (Er,Ce)(2)Fe-17 compounds is shifted to the room temperature around by a small adjustment of the Ce content. The typical lambda-shape (-Delta S-M)-T curves of Er2-xCexFe17 compounds indicate that the phase transition near Curie temperature belongs to the second order one which conduces the compounds with larger magnetic entropy changes in a comparatively wide range of temperature. When the Ce content x is between 0.05 and 0.10, the Er2-xCexFe17 compounds have higher magnetic entropy changes, and the maximal values are about 40 similar to 50% of the highest magnetic entropy changes of the pure metal Gd in the external field of 2 or 5 T. Er2-xCexFe17 compounds are the potential working media for magnetic refrigeration with their stable chemical properties, wide temperature range for magnetic refrigeration and low price.