Development of Giant Magnetostrictive Material by Applying Metamagnetic Transition

本课题的主要研究成果如下：1、巡游电子变磁La（Fe_xSi_）_化合物各向同性巨磁致伸缩的研究La（Fe_xSi<1-x><13>_<1-x>）_<13>化合物（0.86[小于或等于]x[小于或等于]0.90）在居里温度Tc ~ 200 K附近出现巡游电子变磁转变。约1.5%的体积变化是由在转变处约1μ_B的磁化变化引起的。为了将体积变化应用于磁致伸缩材料，通过吸氢将居里温度控制到室温。对于La（Fe_<0.88>Si_<0.12>）_<13>H_<1.0>化合物，T_c值提高到278 K，在室温附近观察到与常规Tafenol相当的大的各向同性体积磁致伸缩。由于La（Fe_xSi_<1-x>）_<13>H_y化合物的磁致伸缩既具有与常规材料相当的大幅度，又具有各向同性的特点， 关于我们 具有多重磁相变的La（Fe_xAl_）_化合物的磁体积效应和磁致伸缩研究La（Fe_xAl_<1-x>）_<13>化合<1-x><13>物在0.60[≤]x[≤]0.86处为铁磁，在0.87[≤]x [≤]0.92处为反铁磁。此外，磁场诱导的一级转变的铁磁状态出现在反铁磁相。此外，在0.86&lt;x&lt;0.87的转变温度T_0处观察到热致一级相变。在巡游电子磁体中，磁矩的幅度在这些相变中发生变化，随后体积发生变化。通过T_0附近的热膨胀测量，观察到约0.5%的各向同性体积变化.此外，它已被证实，各向同性的体积磁致伸缩是由磁场诱导的反铁磁-铁磁转变为x = 0.88。因此，它已被证明，大的各向同性体积磁致伸缩出现的磁矩的幅度由于本发明的化合物中的各种磁相变的显着变化。少

Research results of the present project is summarized as follows.1 Study on Isotropic Giant Magnetostriction of Itinerant-Electron Metamagnetic La (Fe_xSi_<1-x>)_<13> CompoundsLa(Fe_xSi_<1-x>)_<13> Compounds (0.86【less than or equal】x【less than or equal】0.90) exhibit the itinerant-electron metamagnetic transition just above the Curie temperature Tc〜200K. Volume change of about 1.5% is caused by a change in magnetization of about 1μ_B at the transition. To apply the volume change to magnetostrictive materials, the Curie temperature was controlled up to room temperature by hydrogen absorption. For La (Fe_<0.88>Si_<0.12>)_<13>H_<1.0> compound, the value of T_c was elevated up to 278 K, and large isotropic volume magnetostriction comparable in that of conventional Tafenol has been observed around room temperature. Since, the magnetostriction of La (Fe_xSi_<1-x>)_<13>H_y compounds show both the large magnitude comparable to those to the conventional materials and the isotropic feature, the … More compounds can be new magnetstrictive materials which remove the process such as the structural control in constructon of devices.2 Study on Magnetovolume Effect and Magnetostriction in La (Fe_xAl_<1-x>)_<13> Compounds showing Multiple Magnetic Phase TransitionLa (Fe_xAl_<1-x>)_<13> Compounds are ferromagnetic in 0.60【less than or equal】x【less than or equal】0.86, while become antiferromagnetic in 0.87【less than or equal】x【less than or equal】0.92. Furthermore, the magnetic field induced first-order transition to the ferromagnetic state appears in the antiferromagnetic phase. In addition, the thermal induced first-order transition has been observed at the transition temperature T_0 in 0.86<x<0.87. In the itinerant-electron magnets, amplitude of magnetic moment varies in these phase transition followed by volume change. By thermal expansion measurement around T_0, the isotropic volume change of about 0.5 % has been observed. Furthermore, it has been confirmed that the isotropic volume magnetostriction is induced by the magnetic field induced antiferromagnetic-ferromagnetic transition for x = 0.88. Consequently, it has been demonstrated that large isotropic volume magnetostriction is appeared by significant change in amplitude of magnetic moment due to the various magnetic phase transitions in the present compounds. Less