Preparation and characterization of Eu-magadiite intercalation compounds

The intercalation of europium ions (Eu³+) into the interlayer space of a layered silicate, magadiite, was conducted by ion-exchange reactions between magadiite and europium(III) chloride. X-ray diffraction and elemental analysis results indicated that Eu³⁺ cations were intercalated into the interlayer space of magadiite. The ion exchange between Eu³⁺ and Na⁺ occurred preferentially so that the adsorbed Eu³⁺ amounts were controlled quantitatively. Thermal transformation of the original layered structure was suppressed by the intercalation of Eu³⁺. The resulting intercalation compounds exhibited photoluminescence arising from the intercalated Eu³⁺. The luminescence intensity varied in accordance with the amount of Eu³⁺ absorbed, suggesting that the self-quenching occurred at higher loading levels. The luminescence intensity was also changed by the heat treatment, corresponding to the change in the surroundings of the Eu³⁺ adsorbed, induced by the removal of the adsorbed water molecules and the hydroxyl groups of the silicate.