Synthesis and characterization of a novel sodium transition metal oxyfluoride: NaMnMoO3F3·H2O.

摘要: NaMnMoO3F3·H2O was precipitated at low temperature from aqueous dissolutions of Na2MoO4·2H2O in HF (or NaHF2) using either Mn(CH3COO)2·4H2O or MnF2 as manganese precursors. Chemical analysis, IR spectra, and effective paramagnetic moment are agreement with the proposed formula. Electron microscopy studies indicate that sample is constituted very thin plate-like microcrystals. The average crystal structure (a = 3.5947(1), b 21.246(1), c 7.3893(2) A Cmcm (No. 63) SG) has been elucidated through powder diffraction methods (synchrotron neutron). Tiny superstructure peaks observed can be indexed space group Pbca cell parameters a 7.1894(2), A. confirms doubling parameter. Ordering O F Pauling's second rule bond strength sums for each anionic position. formed layered stacking arrangement along b-axis MnO4F2 octahedra layers share corners a- c-directions. large interlayer contains MoO4F2 (connected to layer) together sodium ions water molecules, tentatively forming hydrogen bonding fluorine anions. origin could not fully elucidated, but it presumably related slight distortions within octahedra.