The Luminescence Spectra of Triply-ionized Dysprosium and Terbium in Alkaline Earth Fluorides

Abstract

Abstract (i) The luminescence spectra of dysprosium-(III) and terbium(III) ions have been measured in the cubic field (Oh5) of calcium fluoride, strontium fluoride and barium fluoride under excitation by cathode-ray-bombardment. (ii) The displacement of the luminescence bands of dysprosium (III) ion has been studied with relation to the matrices mentioned above, a blue shift being observed, with 25 and 22 bands as the matrix was changed in successive sequences of calcium fluoride to strontium fluoride and strontium fluoride to barium fluoride respectively. Similarly, this was the case with 35 bands of the terbium (III) luminescence when, the matrix was changed from calcium fluoride to strontium fluoride, and with 33 bands for that from strontium fluoride to barium fluoride. (iii) The magnitude of the relative crystalfield splittings Δν of the luminescence bands of dysprosium (III) and terbium(III) ions was reported in relation to the increasing strength of the crystal field, i.e., in the sequence of matrices barium fluoride, strontium fluoride and calcium fluoride. For the dysprosium (III) luminescence, the crystalfield splittings observed in the 6F11/2→6H11/2, 6F11/2→6H13/2 and 6F11/2→6H15/2 transitions had a tendency to increase in the matrix-sequence barium fluoride, strontium fluoride and calcium fluoride. In the case of the terbium (III) luminescence, variations similar to that found in the dysprosium (III) luminescence took place in the crystalfield splittings of the 5D4→7F3, 5D4→7F4, 5D4→7F5, 5D3→7F2, 5D3→7F3 and 5D3→7F5, transitions, while the reverse was the case with the 5D4→7F6 and 5D3→7F4 transitions. (iv) It was found that the band appearing at 18480cm−1 in the luminescence spectrum of the terbium(III) ion embedded in barium fluoride splits into its respective two components when the terbium ion was embedded in matrices of strontium fluoride and calcium fluoride with a more intense crystalfield strength. The magnitudes of these splittings, 30 and 50cm−1 as observed in strontium fluoride and calcium fluoride respectively, are presumably proportional to the differences between the crystalfield strength for barium fluoride, strontium fluoride and calcium fluoride.