Studies of short-time and high-temperature annealing and magnetic property of LaFe_11.4Si_1.6 compound

Xiang CHEN 1,2) ,Yungui CHEN 1) and Yongbo TANG 1) 1) School of Materials Science and Engineering,Sichuan University,Chengdu 610065,China 2) Department of Physics and Electronic Informational Engineering,Neijiang Teachers College,Neijiang 641002,China

摘 要：The LaFe 11.4 Si 1.6 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K（5 h） to 1623 K（2 h） . The powder X-ray diffraction（XRD） and microstructure observations show that large amount of 1:13 phase begins to appear in the LaFe 11.4 Si 1.6 compound annealed at 1423 K（5 h） . In the temperature range from 1423 K to 1523 K,the α-Fe and LaFeSi phases rapidly decrease to form 1:13 phase. The LaFeSi phase is rarely observed by XRD when the as-cast compound is annealed at 1523 K（5 h） . With annealing temperature increasing to 1573 K,LaFeSi phase is detected again in LaFe 11.4 Si 1.6 compound. In LaFe 11.4 Si 1.6 compounds annealed at 1523 K（5 h） ,at 1373 K（2 h） +1523 K（5 h） ,and 1523 K（7 h） +1373 K（2 h） ,the impurity phases including small amount of α-Fe and LaFeSi phase reduce in turn. The magnetic measurement shows that LaFe 11.4 Si 1.6 compounds annealed by above three processes keep the first-order of magnetic transition behavior,and T C are both at about 200 K. But the values of the maximal S M（T,H） of has large difference,they are 9.94,12.66,and 13.96 J/（kg·K） under a magnetic field of 0-2 T,respectively.

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