AgMo6Te6: Nouveau type structural unidimensionnel a chaiˆnes line´aires|Mo62|1∞

RE3Mo14O30 and RE2Mo9O19, Two Reduced Rare-Earth Molybdates with Honeycomb-Related Structures ( RE = La-Pr)

The previously unreported RE₃Mo₁₄O₃₀ and RE₂Mo₉O₁₉ phases were synthesized in vacuo from rare-earth oxides, molybdenum oxide, and molybdenum metal using halide fluxes at 875-1000 °C. Both phases adopt structures in the triclinic P1̅ space group albeit with several notable differences. The structures display an ordering of layers along the a direction of the unit cell, forming distinct honeycomb-related lattice arrangements composed of MoO₆ octahedra and vacancies. Mo-Mo bonding and clusters are present; the RE₃Mo₁₄O₃₀ structure contains Mo dimers and rhomboid tetramers, while the RE₂Mo₉O₁₉ structure contains rhomboid tetramers and an unusual arrangement of planar tetramers, pentamers, and hexamers. The magnetic measurements found the RE₂Mo₉O₁₉ phases to be simple paramagnets, while La₃Mo₁₄O₃₀ was observed to order antiferromagnetically at 18 K. Electrical resistivity measurements confirmed all of the samples to behave as nondegenerate semiconductors.

New Mo6 Te6 Sub-Nanometer-Diameter Nanowire Phase from 2H-MoTe2

A novel phase transition, from multilayered 2H-MoTe₂ to a parallel bundle of sub-nanometer-diameter metallic Mo₆ Te₆ nanowires (NWs) driven by catalyzer-free thermal-activation (400-500 °C) under vacuum, is demonstrated. The NWs form along the 〈11-20〉 2H-MoTe₂ crystallographic directions with lengths in the micrometer range. The metallic NWs can act as an efficient hole injection layer on top of 2H-MoTe₂ due to favorable band-alignment. In particular, an atomically sharp MoTe₂ /Mo₆ Te₆ interface and van der Waals gap with the 2H layers are preserved. The work highlights an alternative pathway for forming a new transition metal dichalcogenide phase and will enable future exploration of its intrinsic transportation properties.

Synthesis, crystal and electronic structures, and magnetic properties of LiLn9Mo16O35 (Ln = La, Ce, Pr, and Nd) compounds containing the original cluster Mo16O36

The new compounds LiLn(9)Mo(16)O(35) (Ln=La, Ce, Pr, and Nd) were synthesized from stoichiometric mixtures of Li(2)MoO(4), Ln(2)O(3), Pr(6)O(11) or CeO(2), MoO(3), and Mo heated at 1600 °C for 48 h in a molybdenum crucible sealed under a low argon pressure. The crystal structure, determined from a single crystal of the Nd member, showed that the main building block is the Mo(16)O(36) unit, the Mo(16) core of which is totally new and results from the fusion of two bioctahedral Mo(10) clusters. It can also be viewed as a fragment of an infinite twin chain of edge-sharing Mo(6) octahedra. The Mo(16)O(36) cluster units share some oxygen atoms to form infinite chains running parallel to the b axis, which are separated by the rare-earth and lithium cations. (7)Li-NMR experiments, carried out at high field on the nonmagnetic LiLa(9)Mo(16)O(35), provided insights into the local environment of the lithium ions. Magnetic susceptibility measurements confirmed the trivalent oxidation state of the magnetic rare-earth cations and indicated the absence of localized moments on the Mo(16) clusters. The electronic structure of the LiLn(9)Mo(16)O(35) compounds was analyzed using molecular and periodic quantum calculations. The study of the molecular orbital diagrams of isolated Mo(16)O(36) models allowed the understanding of this unique metallic architecture. Periodic density functional theory calculations demonstrated that few interactions occur between the Mo(16) clusters, and predicted semiconducting properties for LiLn(9)Mo(16)O(35) as a band gap of 0.57 eV was computed for the lanthanum phase.