The effect of fullerenes C60 and C70 on the photo- and triboluminescence of terbium sulphate crystallohydrate in the solid phase

Abstract

It was found that the addition of C₆₀ and C₇₀ fullerenes to Tb₂(SO₄)₃·8H₂O crystals led to a decrease in the photo- and triboluminescence intensities of the Tb³⁺ ion, without affecting the positions of its luminescence maxima. An increase in the intensity of the emission band ascribed to fullerene at 630–850 nm, relative to that without terbium sulphate, was also observed in the photoluminescence spectra. The phosphor luminescence was quenched in a mechanical mixture with the quenchers and luminescence sensitization of the quenchers occurred, indicating that quenching took place in the solid phase by a mechanism similar to that observed in solution; this is due to radiationless energy transfer from the excited Tb³⁺ ion to the C₆₀ and C₇₀ molecules. The excitation energy is probably transferred through the contacting crystal surfaces of the phosphor and quencher.