Magnetic Properties of the U 2Fe 17- xM xC y Intermetallic Compounds with M = Al, Si, and Ge

Abstract

"U 2Fe 17" does not exist in thermodynamic equilibrium; however, alloying uranium with electron donor elements such as Al, Si, or Ge yields compound formation with crystal structures isotypic with the Th 2Ni 17-type or derivative structures such as U 2Fe 12.8Si 4.2. The octahedral voids can be partially filled with carbon atoms without exceeding one carbon atom per formula unit. Powder X-ray diffraction of the carbon-containing compounds in all cases revealed the Th 2Ni 17-type of structure with a small increase in volume by ∼0.0075 nm 3 per interstitial carbon atom per formula unit. There is only a small influence of the carbon-induced volume increase on the ferromagnetic ordering temperature of the alloys.