Mossbauer Spectroscopic Study of Neptunium Compounds

对用通量法制备的镎化合物进行了穆斯堡尔光谱分析。特别地，我们应用了日本仅用于复杂化合物的Np-237穆斯堡尔谱分析了NpTGa_5的电子和磁态。Fe-57穆斯堡尔谱适用于NpFeGa_5，其中除了Np位点外，Fe位点也具有磁矩。NpFeGa5在117k以下变为反铁磁体，在4.2 K时超细场达到1.9 T。这一结果与Metoki等人的中子衍射实验结果一致。结果表明，Np原子的磁矩为0.94 μ_B。测量了这些化合物的电阻率、磁化率和比热等物理性质。

Mossbauer spectroscopy has been performed for the neptunium compounds, which were made by flux method. Especially, We applied the Np-237 Mossbauer spectroscopy, which was used only for the complex compounds in Japan, to elucidate the electronic and magnetic state of NpTGa_5. Fe-57 Mossbauer spectroscopy was adapted to NpFeGa_5, in which Fe sites also has magnetic moment in addition to Np sites. NpFeGa5 becomes antiferromagnet below 117 K and Hyperfine field reaches to 1.9 T at 4.2 K. This result consists with the neutron diffraction experiment by Metoki et al. Hyperfine field at Np sites was determined as 204 T indicating that Np atom has a magnetic moment of 0.94 μ_B.Physical properties such as electrical resistivity, magnetic susceptibility and specific heat have measured for these compounds.