Magnetic properties of the U2Fe17-xMxCy intermetallic compounds with M = Al, Si, and Ge

'U2Fe17' 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 Th2Ni17-type or derivative structures such as U2Fe12.8Si4.2. 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 Th2Ni17-type of structure with a small increase in volume by ∼0.0075 nm3 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