Luminescence of Eu3+ and Tb3+ ions adsorbed on hydrated layer-lattice silicate surfaces

Abstract

The luminescence of Eu³⁺ and Tb³⁺ ions which have been cation exchanged on montmorillonite and hectorite clays has been monitored as a function of the amount of water co-adsorbed on the clay. The luminescence intensity of the montmorillonite samples was negligible, probably due to energy transfer to the Fe³⁺ ions of the montmorillonite lattice. With hectorite, the luminescence intensity displayed complex behaviour with a dramatic increase for some hydration states, which was qualitatively rationalized in terms of the rare-earth–clay interactions on the one hand and the rare-earth–water interactions on the other.