Investigation of spectroscopic properties (absorption and emission) of Ho 3+ doped alkali, mixed alkali and calcium phosphate glasses

Abstract

Optical absorption and emission spectra of Ho 3+ doped alkali, mixed alkali and calcium phosphate glasses of the type (69.5NH 4H 2PO 4·15Na 2HPO 4)·15R 2CO 3 (R = Li, Na and K), (69.5NH 4H 2PO 4·15Na 2HPO 4)·7.5Li 2CO 3·7.5R 2CO 3 (R = Na and K), (69.5NH 4H 2PO 4·15Na 2HPO 4)·7.5Na 2CO 3·7.5K 2CO 3 and (69.5NH 4H 2PO 4·15Na 2HPO 4)·15CaCO 3 have been studied. Variation of Judd–Ofelt intensity of parameters ( Ω λ ), peak wavelengths of the hypersensitive transitions ( λ p ), radiative transition probabilities ( A rad) and peak emission cross-sections ( σ p ) with the variation of alkalis, mixed alkalis and calcium in the phosphate glass matrix has been studied. The shift in peak wavelength of the hypersensitive transition and Judd–Ofelt intensity parameter ( Ω 2) are correlated with the structural changes in the host matrix. Radiative lifetimes ( τ R ) are estimated for certain excited states of Ho 3+ in these glass matrices. From the luminescence spectra, the emission cross-sections ( σ p ) are evaluated for the two emission transitions of Ho 3+ ion. Variation of luminescence intensities of the two transitions, absorption and emission cross-sections with the variation of alkalies, mixed alkalies and calcium in the above phosphate glass systems has been studied.