Gd_(60-x)Ho_xCo_(20)Al_(20)非晶合金的磁热效应研究

Large Magnetocaloric Effect on Gd_(60-x)Ho_xCo_(20)Al_(20) Amorphous Ribbons

本文利用单辊熔体快淬法成功制备了Gd_(60-x)Ho_xCo_(20)Al_(20)(x=0-40)非晶合金,并系统研究了其磁性和磁热效应。研究发现:通过Ho替代Gd可实现相变温度在44~112K宽温区内连续可调,并在各自相变温度附近发生铁磁(亚铁磁)—顺磁二级相变。在0~5T外磁场变化下,Gd_(60-x)Ho_xCo_(20)Al_(20)非晶合金磁熵变峰值分别为7.91(x=0),9.22(x=10),8.85(x=20),8.56(x=30),9.83(x=40)J·kg-1·K-1,Gd30Ho30Co20Al20和Gd20Ho40Co20Al20非晶合金的半高宽分别为~60K和~70K,磁制冷效率为~590和~599J·kg-1,有望应用于液氮温区制冷。

In the present research, amorphous ribbons Gd60-xHoxCo20Al20 were fabricated by a single-roller method at a spinning rate of 40 m/s. The phase transition temperature could be tunable in a wide temperature range between 44 and 112 K by varying the Ho concentration x from 0 to40. A typical second order phase transition was found around the respective phase transition temperature. The magnetic entropy change（ΔSM） was calculated from the isothermal magnetization data by employing Maxwell’s relationship. The maximum magnetic entropy change is about 7.91,9.22, 8.85, 8.56 and 9.83 J·kg-1·K-1 under an applied field change of 0-5 T for x=0,10,20,30 and 40.The full-width of the half-maximum of magnetic entropy change（ΔTFWHM） is 60 and 70 K and the refrigerant capacity（RC） is about 590 and 599 J·kg-1 for x=30 and 40, respectively. It could be a very good candidate for magnetic refrigerant near liquid nitrogen temperature range.