Structures and Magnetic Properties of New Inserted Uranium Tellurides: U3Te5Zx (Z=Ge, Sn)

✍ Scribed by Olivier Tougait; Michel Potel; Henri Noël

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 283 KB
• Volume: 168
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2002.9713

✦ Synopsis

The two new compounds U 3 Te 5 Ge 0.7 and U 3 Te 5 Sn 0.5 were prepared by heating the binary compound U 3 Te 5 and the corresponding group 14 element at 8501C in a fused-silica tube. Single crystals have been grown by chemical vapor transport using iodine as transporting agent in temperature gradients of 870-8401C and 840-8001C for U 3 Te 5 Ge 0.7 and U 3 Te 5 Sn 0.5 , respectively. They have been characterized by single-crystal X-ray diffraction measurements and by energy dispersive X-ray analysis. The two isostructural compounds crystallize with two formula units in the orthorhombic space group Pmmn in cells of dimensions: U 3 Te 5 Ge 0.7 a ¼ 4:2764ð1Þ ( A, b ¼ 13:1029ð3Þ ( A, c ¼8:9104ð2Þ ( A; U 3 Te 5 Sn 0.5 , a ¼ 4:3160ð1Þ ( A, b ¼ 13:1999ð4Þ ( A, c ¼ 8:9128ð2Þ ( A. The crystal structures comprise two independent U atoms with two different coordination geometries. Atom U(1) is surrounded by eight Te atoms in a bicapped trigonal prismatic geometry. Atom U( 2) is in a seven coordinate environment of Te atoms, with an arrangement usually described as a 7-octahedron. The three-dimensional packing results in distorted hexagonal cavities where the metalloid atoms are inserted. Magnetic measurements reveal that both compounds U 3 Te 5 Ge 0.7 and U 3 Te 5 Sn 0.5 are hard ferromagnets with ordering temperature of 135 and 140 K, respectively. At low temperature, they display large magnetocrystalline anisotropy with origin on the domain wall pinning at the magnetic domain boundaries.