Synthesis and Characterization of Three New Layered Vanadium Tellurites, MVTe2O8 (M = Al, Ga, and Mn): Three-Dimensional (3-D) Antiferromagnetic Behavior of MnVTe2O8 with a Zigzag S = 2 Spin Chain.

Three new metal vanadium tellurites, MVTe2O8 (M = Al, Ga, and Mn) have been synthesized through standard solid-state and hydrothermal reactions. Crystal structure analyses using X-ray diffraction reveal that the isostructural materials exhibit layered structures consisting of MO6, TeO4, and VO4 polyhedra. The corner-sharing of MO6 octahedra results in one-dimensional (1-D) zigzag chains that are further interconnected by tetrameric Te4O12 units and the VO4 tetrahedra to complete a layered structure. Detailed structural analysis suggests that the unit-cell volumes and the very long Te(2)-O(2) bond distances in MVTe2O8 are closely related to the ionic radii of M(3+) cations. Additional characterizations such as ultraviolet-visible light (UV-vis) and infrared spectroscopies, thermogravimetric analyses, and electron paramagnetic resonance measurements were performed. The temperature-dependent magnetic susceptibility measurements on MnVTe2O8 suggest that the material behaves like a three-dimensional (3-D) antiferromagnet with T(N) = 30 K, although the structure consists of a zigzag S = 2 spin chain.

Cooperative effects of cation size and variable coordination modes of Te(4+) on the frameworks of new alkali metal indium tellurites, NaIn(TeO3)2, KIn(TeO3)2, RbInTe3O8, and CsInTe3O8.

Four new alkali metal indium tellurites, NaIn(TeO3)2, KIn(TeO3)2, RbInTe3O8, and CsInTe3O8, have been prepared through hydrothermal and solid state synthesis reactions using corresponding alkali metal carbonates, In2O3 [or In(NO3)3·xH2O], and TeO2. The structures of the reported materials have been determined by powder and single crystal X-ray diffraction. The mixed indium tellurites reveal a rich structural chemistry with different channel structures. NaIn(TeO3)2 shows 8-membered rings, whereas stoichiometrically similar KIn(TeO3)2 exhibits both 8- and 12-membered rings in the frameworks. Isostructural RbInTe3O8 and CsInTe3O8 reveal three-dimensional frameworks consisting of InO6, TeO3, and TeO4 groups. Close structural examination suggests that the alkali metal cation size and variable coordination modes of Te(4+) cations cooperatively influence the framework geometries of the new mixed metal tellurites. Detailed characterizations including spectroscopic, elemental, and thermal analyses are introduced. Local dipole moments and out-of-center distortions for the constituent polyhedra are also reported.