XPS investigations on the feasibility of isomorphous substitution of octahedral Al3+ for Fe3+ in Keggin ion salts

Investigation of Keggin ion salts prepared by partial hydrolysis of Al3+ and Fe3+ ions followed by addition of sodium sulfate solution to generate the sulfate salt of the Keggin ion was carried out. Characterization of the salts was performed by classical analytical methods and FTIR and XP spectroscopy. Incorporation of iron in the Keggin ion produced a new photoemission peak probably as a satellite in the Fe(2p) XP spectrum. The results suggest that a small portion of Al3+ is replaced by Fe3+ in an octahedral position.