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Experimental studies of novel magnetic refrigerants by high field X-ray diffraction measurements

高场X射线衍射测量新型磁性制冷剂的实验研究

基本信息

批准号：
17560610
负责人：
KOYAMA Keiichi
金额：
$ 2.12万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

In this work, I have studied novel magnetic refrigerants by high X-ray diffraction measurements. I have clarified some topics as follows:1. I observed a field-induced magnetic and structural transition on large magnetocaloric material MnFeP_0.5As_0.5. The material has a hexagonal structure and shows that the parameters a and c deform by 0.5% and 1.0%, respectively, by magnetic field.2. Large magnetocaloric material Gd_5(GeFe)Si_2 shows a structural transformation from a monoclinic structure to an orthorhombic structure by high magnetic field.3. I observed a field-induced reverse martensitic transformation from an orthorhombic structure to a cubic structure in large magnetocaloric material Ni_<50>Mn_<36>Sn_<14>.4. The ferromagnetic shape memory alloy Ni_<50>Mn_<36>Sn_<14> shows a large magnetoresistance effect accompanied by the field-induced reverse martensitic transformation.5. I revealed the magnetic and thermoelectric properties of magnetic shape memory alloy Ni_<50>Mn_<36>Sn_<14> in high magnetic fields.6. I observed a metamagnetic (1st-order) transition of MnBi at high temperature of 630 K by high magnetic fields.7. MnBi shows a large magnetocaloric effect at the 1st-order magnetic transition temperature. By applying high magnetic field, the 1st-order magnetic transition temperature of MnBi increases at the rate of 2 KT^<-1>.8. Magnetic field and pressure induced magnetic transitions were observed in DyB_2C_2 below 10 K.

在这项工作中，我研究了新型磁制冷剂的高X射线衍射测量。我澄清了以下几个问题：1。在大型磁热材料MnFeP_0.5As_0.5上观察到了磁场诱导的磁和结构转变。该材料具有六方结构，并显示出参数a和c的变形分别为0.5%和1.0%，由磁场.大磁热材料Gd_5（GeFe）Si_2在强磁场作用下表现出由单斜晶向正交晶的结构转变.在大型磁热材料Ni_ Mn_ Sn_（0.4）中观察到了场致逆马氏体相变<50><36><14>。铁磁形状记忆合金Ni_<50>Mn_<36>Sn_<14>表现出较大的磁电阻效应，并伴随着场致逆马氏体相变.揭示了磁性形状记忆合金Ni_<50>Mn_<36>Sn_<14>在强磁场下的磁性能和热电性能.在630 K的高温下，在强磁场作用下观察到MnBi的变磁（一级）转变. MnBi在一阶磁转变温度下表现出较大的磁热效应。通过施加强磁场，MnBi的一阶磁转变温度以2KT ^. 8的速率增加<-1>。在低于10 K的温度下观察到了磁场和压力诱导的DyB_2C_2的磁转变。