Polycrystalline Pb3TeCo3V2O14, a structural analogue of the multiferroic Ba3NbFe3Si2O14, was synthesized and characterized using X-ray diffraction, magnetic susceptibility, specific heat, dielectric constant, and neutron diffraction. Magnetic susceptibility, specific heat capacity measurements, and bond valence analysis confirmed that the V5+ ion is nonmagnetic, while Co2+ is in its high spin state (S = 3/2). Two magnetic transitions were seen at T N1 = 8.6 K and T N2 = 6.0 K where the spins first adopt a magnetic structure with propagation vector k⃗ = (0.752,0,1/2) and reorder into a commensurate structure with propagation vector k⃗ = (5/6,5/6,1/2). Changes in the dielectric constant at both magnetic phase transitions suggest that magnetoelectric coupling exists in Pb3TeCo3V2O14.

We report novel details regarding the reactivity and mechanism of the solid-state topotactic reduction of Sr2MnO4 using a series of solid-state metal hydrides. Comprehensive details describing the active reducing species are reported and comments on the reductive mechanism are provided, where it is shown that more than one electron is being donated by H(-). Commonly used solid-state hydrides LiH, NaH, and CaH2, were characterized in terms of reducing power. In addition the unexplored solid-state hydrides MgH2, SrH2, and BaH2 are evaluated as potential solid-state reductants and characterized in terms of their reductive reactivities. These 6 group I and II metal hydrides show the following trend in terms of reactivity: MgH2 < SrH2 < LiH ≈ CaH2 ≈ BaH2 < NaH. The order of the reductants are discussed in terms of metal electronegativity and bond strengths. NaH and the novel use of SrH2 allowed for targeted synthesis of reduced Sr2MnO(4-x) (0 ≤ x ≤ 0.37) phases. The enhanced control during synthesis demonstrated by this soft chemistry approach has allowed for a more comprehensive and systematic evaluation of Sr2MnO(4-x) phases than previously reported phases prepared by high temperature methods. Sr2MnO3.63(1) has for the first time been shown to be monoclinic by powder X-ray diffraction and the oxidative monoclinic to tetragonal transition occurs at 450 °C.

The novel oxide defect fluorite phase ScTiO(3.5) is formed during the topotactic oxidation of ScTiO(3) bixbyite. We report the oxidation pathway of ScTiO(3) and structure evolution of ScTiO(3.5), Sc(4)Ti(3)O(12), and related scandium-deficient phases as well as high-temperature phase transitions between room temperature and 1300 °Cusing in-situ X-ray diffraction. We provide the first detailed powder neutron diffraction study for ScTiO(3). ScTiO(3) crystallizes in the cubic bixbyite structure in space group Ia3 (206) with a = 9.7099(4) Å. The topotactic oxidation product ScTiO(3.5) crystallizes in an oxide defect fluorite structure in space group Fm3m (225) with a = 4.89199(5) Å. Thermogravimetric and differential thermal analysis experiments combined with in-situ X-ray powder diffraction studies illustrate a complex sequence of a topotactic oxidation pathway, phase segregation, and ion ordering at high temperatures. The optimized bulk synthesis for phase pure ScTiO(3.5) is presented. In contrast to the vanadium-based defect fluorite phases AVO(3.5+x) (A = Sc, In) the novel titanium analogue ScTiO(3.5) is stable over a wide temperature range. Above 950 °C ScTiO(3.5) undergoes decomposition with the final products being Sc(4)Ti(3)O(12) and TiO(2). Simultaneous Rietveld refinements against powder X-ray and neutron diffraction data showed that Sc(4)Ti(3)O(12) also exists in the defect fluorite structure in space group Fm3m (225) with a = 4.90077(4) Å. Sc(4)Ti(3)O(12) undergoes partial reduction in CO/Ar atmosphere to form Sc(4)Ti(3)O(11.69(2)).

Topotactic Solid-State Metal Hydride Reductions of Sr 2MnO4. -The reactivity and mechanism of the solid state topotactic reduction of Sr 2MnO4 using the series of metal hydrides LiH, NaH, CaH 2, MgH2, SrH2, and BaH2 are characterized by powder XRD and TGA/DTA. In terms of reactivity the metal hydrides show the trend MgH2 < SrH2 < LiH  CaH2  BaH2 < NaH. NaH and SrH2 allow for targeted synthesis of reduced Sr 2MnO4-x (0  x  0.37) phases. Sr2MnO3.63 crystallizes in the monoclinic space group P2 1/c with Z = 8, and exhibits an oxidative monoclinic to tetragonal transition at 450 C. Sr2MnO3.69 crystallizes in the tetragonal space group I4/mmm with Z = 2. -(HERNDEN, B. C.; LUSSIER, J. A.; BIERINGER*, M.; Inorg. Chem. 54 (2015) 9, 4249-4256, http://dx.

T he following graphic replaces the Table of Contents and Abstract graphics that were published with the original paper.