C对Gd_5Si_4磁致冷材料结构和性能的影响

Effect of C on the phase formation and magnetocaloric of Gd_5Si_4

以商业蒸馏Gd为原料，采用非自耗电弧炉在氩气保护下熔炼了Gd5Si4Cx（x=0、0．24、0．35、0．5）系列合金，研究了C对Gd5Si4磁致冷合金组织结构与磁热性能的影响。粉末XRD结果表明，Gd5Si4Cx系列合金主相均为正交的Gd5Si4型结构，此外C（x=0．24、0．35、0．5）加入后合金中出现了少量的GdSi相。利用振动样品磁强计测量的合金的磁性能的结果表明，Gd5Si4Cx（x=0、0．24、0．35、0．5）系列舍金的居里温度Tc在344～297K连续可调。在1．5T外加磁场变化时居里温度附近的最大磁熵变分别是2．79、2．47、2．03、1．65J／（kg·K）。

Gd5Si4Cx （x=0,0.24,0. 35,0. 5） alloys were prepared by arc melting under argon atmosphere with the use of 99.9wt% gadolinium. The effect of C on the phase formation and magnetcaloric of Gd5Si4 were studied in the work. Powder XRD results show that Gd5Si4Cx （x=0,0. 24,0. 35,0. 5） have the orthorhombic Gd5Si4-type structure,and small GdSi phase was found in this alloys with the addition of C. Magnetic measurements indicate that,the TC of Gd5Si4Cx could be tuned continually by C from 344 to 297K. The maximal magnetic entropy of the Gd5Si4Cx alloys near TC in a 1.5T field change are 2.79, 2.47, 2.03,1.65J/（kg · K）, respectively.