SYNTHESIS OF VANADIUM BRONZES BA-2+V2O5, NI-2+V2O5, AL-3+V2O5, FE-3+V2O5 THROUGH SOL-GEL PROCESSES .2. ORTHORHOMBIC BRONZES

The bronzes MxV2O5 (M=Ba2+,Ni2+,Al3+,Fe3+) are synthesized via a sol-gel process (SGP bronzes). New compounds have been prepared: they have an α orthorhombic structure which differs considerably from the structures of the same compounds prepared by solid state reaction (SSR bronzes). The thin layers which have been obtained show preferred orientation. The orientation-type depends on the cation: the layers parallel to the substrate are either parallel to the V2O5 orthorhombic layers plane (case of Fe3+ and Al3+), either perpendicular to it (case of Ba2+), either parallel or perpendicular to it (case of Ni2+). The interpretation in terms of a structural filiation between the hydrate phase and the oxide phase can be applied to the exchanged xerogel and the bronze. © 1990.