Synthesis of neptunium trichloride and measurements of its melting temperature

三塩化ネプツニウムの調製と融点測定

林 博和 ; 高野 公秀 ; 倉田 正輝 ; 湊 和生 

Hayashi, Hirokazu; Takano, Masahide; Kurata, Masaki; Minato, Kazuo

酸化ネプツニウムを原料として炭素熱還元法によって調製した窒化ネプツニウムと塩化カドミウムの反応によって高純度の三塩化ネプツニウムを調製した。粉末X線回折法によって測定した六方晶の三塩化ネプツニウムの格子定数はa=0.74210.0006nm及びc=0.42680.0003nmで、これまでの報告値(a=0.7420.001nm, c=0.42810.0005nm)とよく一致した。約1mgの試料を金製の容器中に密封し、示差熱分析装置を用いて測定した融解温度は10703Kであった。これは、これまでに実測値の報告がないために推奨値として採用されているUClの融解温度(1115K)とPuClの融解温度(1041K)の中間値である107530Kに近い値である。

Neptunium trichloride of high purity was synthesized by the solid-state reaction of neptunium nitride, which was prepared from the oxide by the carbothermic reduction method, and cadmium chloride in a similar manner as reported for synthesis of AmCl. Lattice parameters of hexagonal NpCl were determined from the X-ray diffraction pattern to be a = 0.7421 0.0006 nm and c = 0.4268 0.0003 nm, which fairly agree with the reported values (a = 0.742 0.001 nm and c = 0.4281 0.0005 nm). Melting temperature of NpCl was measured with about 1 mg of the sample which was hermetically encapsulated in a gold crucible using a differential thermal analyzer with heating and cooling rate of 10 K/min in an argon gas flow (50 mL/min). The melting temperature of NpCl was determined to 1070 3 K, which is close to the recommended value 107530 K, which was derived from the mean value of the melting temperature for UCl(1115K) and that for PuCl (1041 K).