Pr_(5-x)Gd_xSi_3合金的磁热效应

Magnetocaloric Effect in Pr_(5-x)Gd_xSi_3 Alloys

研究了Pr5-xGdxSi3合金的晶体结构、磁性和磁热效应.X射线衍射结果表明:Pr5-xGdxSi3(x=1.0,2.0)合金结晶为四方Cr5B3型晶体结构;x≥3时,合金由四方Cr5B3型晶体结构转变成六角Gd5Si3型晶体结构;x=1.0时,合金的M-T曲线上出现由亚铁磁性的两个次晶格内的磁化强度各自对温度的变化率不同所致的峰.Pr5-xGdxSi3(x=2.0,3.0)合金的居里温度分别为135K和145K.在0～1.5T的外磁场变化下,Pr5-xGdxSi3(x=2.0,3.0)合金的最大磁熵变分别为1.0J/(kg.K)和0.3J/(kg.K).

The structural, magnetic properties and magnetic-entropy changes of Pr5-xGdxSi3 alloys with x = 1.0,2.0,3.0 and 4.0 were investigated. X-ray diffraction study shows that Pr5-xGdxSi3（x= 1.0, 2.0） alloys crystallize in Cr5B3-type structure. A structural transition from Cr5B3-type structure to Gd5Si3- type structure is observed in the alloys with x≥3.0. Magnetic measurements show that Curie temperature of the alloys increases from 135 K to 145 K for x= 2.0 and x= 3.0. A peak appears in M- T curves in Pr4GdSi3 alloy because of the differences between the temperature dependence of magnetization in two sublattices. The largest magnetic-entropy changes derived from magnetization data are 1.0 J/（kg· K） for x=2.0 and 0.3J/（kg · K） for x=3.0 under a field change from 0 to 1.5T.