136479-02-2Relevant articles and documents
Inelastic neutron scattering studies of the proton dynamics in Bi-doped manganese oxides
Filiaux,Cachet,Parker,Tomkinson,Quivy,Yu
, p. 4184 - 4188 (2000)
The inelastic neutron scattering (INS) spectra from 16 to 4000 cm-1 are presented for lamellar-like manganese dioxides at 30 K: δ-MnO2 and chemically modified Bi-δ-MnO2 at various reduction degrees (Bi-δ-MnO 1.96, Bi-δ-MnO1.88, Bi-δ-MnO1.78, Bi-δ-MnO1.70 and Bi-δ-MnO1.51). Three different types of protons are distinguished: water-like entities at 540 cm-1 , oxoniumlike entities at 815 cm-1, and free protonic entities giving a continuum with constant intensity. The nonreduced samples contain equimolecular mixtures of water-like and oxonium-like entities, and there is no visible modification of the spectra attributable to the Bi entities. As the reduction degree increases, the band intensity at 540 cm-1 decreases and that at 815 cm-1 increases. Free protons are virtually unaffected. Even for the most reduced sample, there is no evidence for any feature specific to protons inserted in the [MnO6] layers. Two processes can be distinguished: the removal of water molecules by the solvent on the one hand and the protonation of water-like entities on the other.
