Phase Equilibrium in the System Ln-M-O: III. Ln=Gd at 1100°C

This communication reports the first intercalation into VOPO4·2H2O performed through a solid-state reaction at room temperature. Ethyleneurea, EU (2-imidazolidone) was intercalated into the oxovanadium phosphate by grinding in a mortar stoichiometric amounts of both reagents at room temperature for 30 min. C, H and N elemental analyses of the obtained intercalation compound gave the formula VOPO4·(EU)·H2O. The profile of the absorption bands due to the VOPO4 lattice vibration around 1000 cm-1 was retained after reaction, providing evidence that an intercalation compound and not merely a salt of V-P-O species was produced. For ALPHA-VOPO4·2H2O, the interlayer distance is 0.75 nm, whereas for the EU inter-calation compound it is 0.95 nm. The obtained SEM micrographs show that the microstructure of VOPO4·2H2O is changed after reaction, with a total exfoliation of the oxovanadium matrix.