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利用电弧熔炼制备出单相的TmGa化合物,TmGa显示了两个连续的相变:在11.5 K处为反铁磁到反铁磁(AFMΙ-AFMΠ)相变,在15 K处为反铁磁到顺磁(AFMΠ-PM)相变。反铁磁区域存在场诱导的反铁磁到铁磁(AFM-FM)变磁转变。虽然TmGa的基态是反铁磁,但是当在较低磁场(0.02 T)下,在12 K附近诱导出铁磁态,因此在一定磁化强度范围内存在AFMΙ-FM,FM-AFMП和AFMП-PM相变。当磁场为0.2 T时AFMΠ态完全消失,AFM-PM的转变成为FM-PM的转变。低温AFMΙ态随磁场的变化是不可逆的,而AFMΠ态随磁场的变化是可逆的。根据温度和磁场的变化绘制了TmGa的磁相图。TmGa在相变温度附近具有较大的磁熵变(-ΔSM),当磁场变化为5 T时,最大-ΔSM为34.2J·kg-1·K-1。值得注意的是,在磁场变化为1和2 T时,最大-ΔSM分别为12.9和20.7 J·kg-1·K-1。同时通过计算得到在1,2和5 T下的磁制冷能力(RC)分别为69,149和364 J·kg-1。TmGa化合物作为低温磁制冷材料潜在巨大应用前景。
Single-phase TmGa compounds were prepared by arc melting. TmGa showed two successive phase transitions: an antiferromagnetic to antiferromagnetic (AFM1-AFMΠ) transformation at 11.5 K and an antiferromagnetic to 15 K Paramagnetic (AFMΠ-PM) phase transition. Field-induced antiferromagnetic to ferromagnetic (AFM-FM) magnetization transformation exists in the antiferromagnetic region. Although the ground state of TmGa is anti-ferromagnetic, the ferromagnetic state is induced near 12 K at a lower magnetic field (0.02 T), so AFM1-FM, FM-AFMП and AFMП-PM exist in a range of magnetization Phase change. When the magnetic field is 0.2 T, the AFMΠ state disappears completely, and the transition of AFM-PM becomes the transition of FM-PM. The low-temperature AFMV state is irreversible with the change of the magnetic field, while the AFMΠ state is reversible with the change of the magnetic field. According to the changes of temperature and magnetic field, the magnetic phase diagram of TmGa is drawn. TmGa has a large magnetic entropy change (-ΔSM) near the phase transition temperature, and the maximum -ΔSM is 34.2 J · kg -1 · K-1 when the magnetic field changes to 5 T. It is worth noting that the maximum -ΔSM is 12.9 and 20.7 J · kg-1 · K-1 when the magnetic field changes to 1 and 2 T, respectively. At the same time, the magnetic refrigeration capacity (RC) at 1, 2 and 5 T were calculated to be 69,149 and 364 J · kg-1, respectively. TmGa compounds as potential applications for cryogenic magnetic refrigeration materials.