CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF THE BINARY TRIURANIUM PENTATELLURIDE U3TE5

The crystal structure of the binary uranium telluride U3Te5 has been d etermined for the first time from single-crystal X-ray; diffraction da ta. This compound crystallizes with a new structure type, in the ortho rhombic space group Pnma (No. 62), with the unit cell parameters a = 1 6.098(7) Angstrom, b = 4.210(2)Angstrom, c = 14.060(4) Angstrom, Z = 4 . The structure has been refined to an agreement index of R(F)= 0.049 and R-omega(F)= 0.050 for 50 variables and 1322 observations [I> 3 sig ma(I)]. The three nonequivalent uranium atoms are coordinated to eight tellurium atoms in bicapped trigonal prismatic arrangements. These pr isms are stacked along the b axis by sharing their triangular faces an d are linked by edge sharing to form a 6-fold capped triprism which is the repeating building unit of the structure. Magnetic measurements r eveal ferromagnetic behavior below approximate to 120 K with a signifi cant span reorientation around 45 K, In the paramagnetic region U3Te5 follows a modified Curie-Weiss law with an effective magnetic moment o ff 2.69 mu(B)/U atom and chi(0) = 3.0316 x 10(-3) emu/mol. (C) 1998 Ac ademic Press.