Luminescence of lanthanide(III) sulfate crystals under photo-, X-ray and triboexcitation

The comparative studies of the luminescent characteristics (photo-, X-ray, triboluminescence spectra, lifetime of excited states and quantum yield of photoluminescence) of crystalline hydrates of lanthanide(III) sulfates (Ce, Pr, Sm, Eu, Gd, Tb, Dy) were carried out. The positions of the Ln(III) ions bands in the triboluminescence spectra of the studied compounds coincide with the positions in the photo- and X-ray luminescence spectra, which indicates the identity of the luminescence emitters. It has been shown that the triboluminescence spectrum of inorganic lanthanide salts in the air atmosphere is caused by gas (emitter – N$_2$) and solid-state (emitter – Ln(III)) components. The excitation of Ln$^{3+}$ triboluminescence occurs according to the type of electroluminescence, namely due to the separation and recombination of charge carriers in the electric field of the crystal volume.