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Title: Hydrothermal synthesis and characterization of M{sub 2}Te{sub 3}O{sub 8} (M = Mn, Co, Ni, Cu, Zn): A series of compounds with the spiroffite structure

Journal Article · · Journal of Solid State Chemistry
; ;  [1]
  1. Clemson Univ., SC (United States). Dept. of Chemistry

Several compounds isotypic to the mineral spiroffite were obtained as high quality single crystals via hydrothermal reactions. These materials, which have the general formula M{sub 2}Te{sub 3}O{sub 8}, crystallize in the monoclinic space group C2/c and contain divalent transition metal ions and tellurite building blocks. Typical synthetic conditions for the /preparation of these materials are 375 C for 3--5 days in an aqueous NH{sub 4}Cl solution. This structure type is based on slabs containing Te{sub 2}O{sub 6} groups joined by M cations. These Te{sub 2}O{sub 6} groups are made up of two edge-sharing TeO{sub 3+1} polyhedra. The metal tellurite slabs are connected to one another through tellurium(IV) atoms, which are coordinated by four oxygen atoms in a regular TeO{sub 4} trigonal bipyramidal configuration. A detailed structural characterization via single crystal X-ray diffraction was performed on four compounds (Co{sub 2}Te{sub 3}O{sub 8}: a = 12.690(1) {angstrom}, b = 5.211(2) {angstrom}, c = 11.632(2) {angstrom}, {beta} = 98.98(1){degree}, V = 759.7(3) {angstrom}{sup 3}, R(R{sub w}) = 0.023 (0.046); Ni{sub 2}Te{sub 3}O{sub 8}: a = 12.407(1) {angstrom}, b = 5.207(1) {angstrom}, c = 11.509(1) {angstrom}, {beta} = 98.723(9){degree}, V = 735.0 {angstrom}{sup 3}, R(R{sub w}) = 0.025 (0.033); Cu{sub 2}Te{sub 3}O{sub 8}: a = 11.8368(8) {angstrom}, b = 5.266(2) {angstrom}, c = 12.2419(8) {angstrom}, {beta} = 100.316(6){degree}, V = 750.7(2) {angstrom}{sup 3}, R(R{sub w}) = 0.025 (0.032); Zn{sub 2}Te{sub 3}O{sub 8}: a = 12.681(2) {angstrom}, b = 5.200(2) {angstrom}, c = 11.786(2) {angstrom}, {beta} = 99.60(1){degree}, V = 766.3(3) {angstrom}{sup 3}, R(R{sub w}) = 0.031 (0.041)). The manganese analog (a = 12.896(5) {angstrom}, b = 5.398(2) {angstrom}, c = 11.907(5) {angstrom}, {beta} = 98.14(4){degree}) was identified via powder diffraction patterns. The cobalt, nickel, and copper compounds were observed to have an antiferromagnetic transition by DC magnetic susceptibility measurements. The band gaps were obtained by optical diffuse reflectance spectroscopy and show that these compounds are all wide band gap materials.

Sponsoring Organization:
National Science Foundation, Washington, DC (United States)
OSTI ID:
338450
Journal Information:
Journal of Solid State Chemistry, Vol. 143, Issue 2; Other Information: PBD: Mar 1999
Country of Publication:
United States
Language:
English