Spectroscopic properties of HoAl3(BO3)4 single crystal

• Polarized absorption spectra of the stoichiometric crystal HoAl3(BO3)4.
• Judd–Ofelt parameters of the f–f transitions.
• Spectroscopic characteristics of the f–f transitions.
• Three luminescence bands in the visible.
• Kinetic equations explaining the relative luminescence intensities.

The Judd–Ofelt theory has been applied to analyze absorption spectra of Ho3+ ion in HoAl3(BO3)4 measured in spectral range 300–700 nm at room temperature. The Judd–Ofelt spectroscopic parameters have been determined as: Ω2 = 18.87 × 10−20 cm2, Ω4 = 17.04 × 10−20 cm2, Ω6 = 9.21 × 10−20 cm2. These parameters have been used to calculate radiative lifetimes and branching ratios of the luminescence manifolds. Three luminescent bands were found in the spectral range 450–700 nm ascribed to transitions from the 5F5, (5F4, 5S2) and 3K8 states to the ground state 5I8. Experimental intensities of these luminescence transitions were compared with those calculated by using Judd–Ofelt theory and the system of kinetic equations for populations of starting luminescing states. Probabilities of radiativeless transitions were evaluated from this comparison.