Luminescence centers in anhydrite,barite, celestite and their synthesized analogs

The intrinsic luminescence center (LC) of SO ₄ ^2? appears at 360 nm in all types of sulfates, but is absent in sulfates with large quantities of impurities. Three nonequivalent Gd³⁺ LC have been observed in luminescence spectra of anhydrite. Gd³⁺, Ce³⁺ O ₂ ^? LC were established in celestite. Photoluminescence (PL) bands in the sulfates were assigned as follows: the band at 460 nm is related to Eu²⁺ (a connection with Al³⁺ or donor-acceptor pair is possible also) in sulfates of Ca and Ba; bands at 520 nm and 590 nm are related to VO₄, MoO₄ and TiO₄ substituting SO₄; the band at 660 nm is assigned to Ti³⁺ X-ray luminescence (XL) band at 620 nm is assigned to Ag⁺.