Development of Giant Magnetostrictive Material by Applying Metamagnetic Transition

1.巡回电子超磁La(Fe_xSi_&lt；1-x&gt；)_&lt；13&gt；化合物La(Fe_xSi_&lt；1-x&gt；)_&lt；13&gt；化合物(0.86[小于等于]x[小于等于]0.90)在居里温度T_c~200K以上表现出巡回电子超磁转变。约1.5%的体积变化是由相变时约1μ_B的磁化强度变化引起的。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。La-(Fe_&lt；0.88&gt；Si_&lt；0.12&gt；)_&lt；13&gt；H_&lt；1.0&gt；化合物的T_c值提高到278K，在室温附近观察到了与常规他芬诺相当的大的各向同性体积磁致伸缩。由于La(Fe_xSi_1-x&gt；)_13&gt；H_y化合物的磁致伸缩既表现出与传统材料相当的大磁致伸缩，又表现出各向同性特征，…La(Fe_xAl_&lt；1-x&gt；)_(13&gt；)化合物的磁体效应和磁致伸缩效应研究化合物在0.60[小于或等于]x[小于或等于]0.86时是铁磁性的，而在0.87[小于或等于]x[小于或等于]0.92时变为反铁磁性。此外，在反铁磁相中还出现了磁场诱导的一级铁磁态转变。此外，在0.86&lt；x&lt；0.87的转变温度T_0处观察到了热致一级相变。在巡回电子磁体中，磁矩的幅值在这些相变过程中随体积变化而变化。通过T_0附近的热膨胀测量，观察到各向同性体积变化约为0.5%。此外，还证实了各向同性体积磁致伸缩是由x=0.88的磁场诱导的反铁磁-铁磁相变引起的。结果表明，由于化合物中不同的磁相变，磁矩的幅值发生了显著的变化，从而产生了大的各向同性体积磁致伸缩。较少

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