La3TWS3O6 (T = Cr, Mn, Fe, Co, Ni): Quinary Rare Earth Transition‐Metal Compounds Showing a Nonmagnetic/Magnetic Transition (T = Co) – Synthesis, Structure and Physical Properties

Abstract

AbstractThe title compounds were synthesized from La2O3, T (T = Cr, Mn, Fe, Co, Ni), sulfur, tungsten and WO3 under vacuum at 950 °C. They crystallize in the space group P63/m (No. 176). The lattice constants for the chromium compound are a = 9.442(2) Å and c = 5.506(2) Å. Those for the other compounds are similar. The electron partition of (La3+)3T3+W6+(S2–)3(O2–)6 indicates that the transition metals in this structure all have a 3+ oxidation state and the solid is a normal valence compound. In this structure, the TS6/2 octahedra form chains parallel to the c axis by sharing faces. In the chromium compound, the Cr–Cr distance in the octahedron chain is 2.7531 Å. The tungsten atoms in the structure are at the centers of O6 trigonal prisms, whereas lanthanum atoms form trigonal prisms enclosing the tungsten atoms. Resistivity and susceptibility measurements reveal the insulating nature and nonmagnetic to magnetic transition of the cobalt compound.