如何评价开发的新型材料是否适合在室温磁制冷机中使用,有不同的看法。将最近报道的有影响的磁制冷材料如Gd Si Ge系列合金,La Fe Si系列合金与金属钆进行对比,说明不能仅仅根据等温磁熵变的数据判断它是否适用于磁制冷机中。应该以金...如何评价开发的新型材料是否适合在室温磁制冷机中使用,有不同的看法。将最近报道的有影响的磁制冷材料如Gd Si Ge系列合金,La Fe Si系列合金与金属钆进行对比,说明不能仅仅根据等温磁熵变的数据判断它是否适用于磁制冷机中。应该以金属钆作为室温磁制冷材料的基准材料,全面评定各个新开发的磁制冷材料的绝热温变、使用温度区间、单位体积磁熵变等参数。数据说明,金属钆在综合性能上具有优势,是目前室温磁制冷机主要采用的磁制冷剂。展开更多
The magnetocaloric effect（MCE） of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various c...The magnetocaloric effect（MCE） of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various crystal structures and magnetic properties, which then result in different MCE. Large MCE has been observed not only in the typical ferromagnetic materials but also in the antiferromagnetic materials. The magnetic properties have been studied in detail to discuss the physical mechanism of large MCE in RT X compounds. Particularly, some RT X compounds such as Er Fe Si,Ho Cu Si, Ho Cu Al exhibit large reversible MCE under low magnetic field change, which suggests that these compounds could be promising materials for magnetic refrigeration in a low temperature range.展开更多
With the intention to explore excellent magnetocaloric materials, the intermetallic compound GdPd was synthesized by arc melting and heat treatment. The microstructure, magnetic and magnetocaloric properties of the in...With the intention to explore excellent magnetocaloric materials, the intermetallic compound GdPd was synthesized by arc melting and heat treatment. The microstructure, magnetic and magnetocaloric properties of the intermetallic compound of GdPd were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and the physical property measurement system（PPMS）. A large reversible magnetocaloric effect is observed in GdPd accompanied by a second order magnetic phase transition from paramagnetism to ferromagnetism at ～39 K. The paramagnetic Curie temperature（θp） and the effective magnetic moment（μ（eff））are determined to be 34.7 K and 8.12 μB/Gd,respectively. The maximum entropy change（｜△SM（Max）｜） and the relative cooling power（RCP） under a field change of 5 T are estimated to be 20.14 J/（kg·K） and 433 J/kg, respectively. The giant reversible magnetocaloric effects（both the large△SM and the high RCP） together with the absence of thermal and field hysteresis make the GdPd compound an attractive candidate for low-temperature magnetic refrigeration.展开更多
文摘如何评价开发的新型材料是否适合在室温磁制冷机中使用,有不同的看法。将最近报道的有影响的磁制冷材料如Gd Si Ge系列合金,La Fe Si系列合金与金属钆进行对比,说明不能仅仅根据等温磁熵变的数据判断它是否适用于磁制冷机中。应该以金属钆作为室温磁制冷材料的基准材料,全面评定各个新开发的磁制冷材料的绝热温变、使用温度区间、单位体积磁熵变等参数。数据说明,金属钆在综合性能上具有优势,是目前室温磁制冷机主要采用的磁制冷剂。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.5137102611274357+1 种基金and 51327806)the Fundamental Research Funds for the Central Universities(Grant Nos.FRF-TP-14-011A2 and FRF-TP-15-002A3)
文摘The magnetocaloric effect（MCE） of RT Si and RT Al systems with R = Gd–Tm, T = Fe–Cu and Pd, which have been widely investigated in recent years, is reviewed. It is found that these RT X compounds exhibit various crystal structures and magnetic properties, which then result in different MCE. Large MCE has been observed not only in the typical ferromagnetic materials but also in the antiferromagnetic materials. The magnetic properties have been studied in detail to discuss the physical mechanism of large MCE in RT X compounds. Particularly, some RT X compounds such as Er Fe Si,Ho Cu Si, Ho Cu Al exhibit large reversible MCE under low magnetic field change, which suggests that these compounds could be promising materials for magnetic refrigeration in a low temperature range.
基金Project supported by the National Basic Research Program of China(2014CB643703)the National Key Research and Development Program of China(2016YFB0700901)the National Natural Science Foundation of China(51261004,51461012)
文摘With the intention to explore excellent magnetocaloric materials, the intermetallic compound GdPd was synthesized by arc melting and heat treatment. The microstructure, magnetic and magnetocaloric properties of the intermetallic compound of GdPd were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and the physical property measurement system（PPMS）. A large reversible magnetocaloric effect is observed in GdPd accompanied by a second order magnetic phase transition from paramagnetism to ferromagnetism at ～39 K. The paramagnetic Curie temperature（θp） and the effective magnetic moment（μ（eff））are determined to be 34.7 K and 8.12 μB/Gd,respectively. The maximum entropy change（｜△SM（Max）｜） and the relative cooling power（RCP） under a field change of 5 T are estimated to be 20.14 J/（kg·K） and 433 J/kg, respectively. The giant reversible magnetocaloric effects（both the large△SM and the high RCP） together with the absence of thermal and field hysteresis make the GdPd compound an attractive candidate for low-temperature magnetic refrigeration.
