Investigation of spectroscopic properties (absorption and emission) of Ho3+ doped alkali, mixed alkali and calcium phosphate glasses

Optical absorption and emission spectra of Ho3+ doped alkali, mixed alkali and calcium phosphate glasses of the type (69.5NH4H2PO4·15Na2HPO4)·15R2CO3 (R = Li, Na and K), (69.5NH4H2PO4·15Na2HPO4)·7.5Li2CO3·7.5R2CO3 (R = Na and K), (69.5NH4H2PO4·15Na2HPO4)·7.5Na2CO3·7.5K2CO3 and (69.5NH4H2PO4·15Na2HPO4)·15CaCO3 have been studied. Variation of Judd–Ofelt intensity of parameters (Ωλ), peak wavelengths of the hypersensitive transitions (λp), radiative transition probabilities (Arad) and peak emission cross-sections (σp) 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 (Ω2) are correlated with the structural changes in the host matrix. Radiative lifetimes (τR) are estimated for certain excited states of Ho3+ in these glass matrices. From the luminescence spectra, the emission cross-sections (σp) are evaluated for the two emission transitions of Ho3+ 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.