The luminescence properties of rare-earth ions in natural fluorite

For the first time, the luminescence properties of Pr 3+, Nd 3+ and Tm 3+ and Yb 3+ ions in fluorite crystal have been obtained by steady-state measurements. In addition, the luminescence spectra of Ce 3+, Sm 2+, Sm 3+, Dy 3+, Er 3+ and Yb 3+ were measured. It was pointed out that λ exc. = 415 nm is most suitable for measuring the Ho 3+ emission beside the Er 3+. The emission of trivalent holmium and erbium ions was measured independently using time-resolved measurements and tentative assignment of luminescence lines to C 3v and C 4v symmetry sites was proposed. Besides for natural fluorite crystal, the transitions between Stark energy levels of lanthanide ions were presented