Jose Fripiat

Ir and Mossbauer Study of Iron Glycerolates

Abstract Iron glycerolates obtained from the reaction between Fe(II) and Fe(III) oxylates and glycerol were studied by means of X-ray diffraction, IR and Mossbauer spectroscopy. Regardless of the oxidation state of iron in the starting salt, the final glycerolates contain nearly identical Fe 2+ /Fe 3+ ratios, but the crystallization from Fe(III) oxalate proceeds faster. As shown by Mossbauer spectroscopy, the first particles of glycerolate obtained from ferric oxalate contain only Fe 3+ species, whereas from ferrous oxalate, Fe 2+ and Fe 3+ are initially present in the glycerolate. Well crystallized glycerolate exhibits three Mossbauer doublets; two are due to Fe 2+ species in different environments and one to Fe 3+ species. Spectral features observed by IR spectroscopy are accounted for by the presence of both structural Fe 2+ and Fe 3+ species.

Hydrogen bronzes from VMoO/sub 5.5/: an X-ray diffraction investigation

Hydrogen bronzes obtained by spillover of hydrogen onto Pt particles deposited on the surface of VMoO/sub 5.5/ have been examined by X-ray diffraction. The results show that H/sub 3.4/VMoO /sub 5.5/ is crystalline and that no intermediate crystalline phase is formed during the insertion of hydrogen in the host lattice. Oxidation of the bronze restores the initial oxide phase. Upon back-titration with H/sub 2/ at 60 degrees C, the bronze phase reappears (indicating the reversible character of these bronzes) at a much higher rate than when the bronze is formed for the first time.