稀土合金Gd1-xNdxTiGe的制备及结构和磁热效应

Preparation,Structure and Magnetocaloric Effects of Rare Earth Alloy Gd1-xNdxTiGe

将稀土元素Gd用部分稀土元素Nd进行替代,利用真空电弧熔炼法制备了Gd1-xNdxTiGe(x=0,0.2,0.4)合金样品,并在800℃进行真空退火处理。通过X射线衍射分析了样品的物相结构,结果表明,Gd1-xNdxTiGe材料为CeFeSi型结构和CeScSi型结构的混合相,主要以CeFeSi型结构相为主,少量存在CeScSi型结构相。利用VSM测量Gd1-xNdxTiGe材料的磁化强度随温度的变化(100 K^400 K),得到其M-T曲线,结果表明,用Nd(x=0.2,0.4)代替部分Gd后居里温度相对于未替代样品(x=0)的居里温度均有下降,未退火样品的居里温度低于退火处理样品的居里温度。对Gd0.6Nd0.4TiGe样品进行了不同温度下其磁化强度随磁场强度的变化的测试,给出了M-B曲线图;利用热力学Maxwell关系得出了表征材料磁热效应的△Sm-T曲线及Arrott曲线,研究了Gd1-xNdxTiGe材料的磁性和磁热效应。研究表明,Gd0.6Nd0.4TiGe随着温度的升高由铁磁性转变为顺磁性,相变为二级相变,具有良好的磁熵变现象,居里温度点为310 K。

The rare earth alloys Gd1-xNdxTiGe were prepared by vacuum arc melting method using Nd partially replace rare-earth element Gd.The annealing was at 800℃in Muff furnace.The phase structures of the samples were analyzed by X-ray diffraction.The results show that the samples of Gd1-xNdxTiGe alloys form a mixture phase with CeScSi-type structure and CeFeSi-type structure.The main phase is with CeFeSi type structure,while a small amount of CeScSi structure phase coexists.The magnetization of Gd1-xNdxTiGe samples was measured with VSM in the temperature change of 100~400 K,and their respective M-T curves were obtained.The results show that the Curie temperature of the samples before and after annealing was decreased with Nd(x=0.2,0.4)replacing part of Gd.The Curie temperature of the unannealed sample is lower than that of the corresponding annealed sample.Gd0.6Nd0.4TiGe sample was selected to test the variation of magnetization with magnetic field at different temperatures,and the M-B curves were given.The magnetocaloric effects of Gd1-xNdxTiGe materials were studied by using the Maxwell relation.The study shows that Gd0.6Nd0.4TiGe alloys undergo a transition from ferromagnetism to paramagnetism with the increase of temperature,and the phase transition is of second-order,with a moderate magnetic entropy change values,and Curie temperature is about 310 K.