Optical properties and Judd–Ofelt parameters of Dy3+ doped K2GdF5 single crystal

•The energy transfer occurs from Gd3+ to Dy3+.•The bonding of Dy3+ ions with the local host is ionic bonding.•The coordination structure surrounding the RE ion has high symmetry.•4F9/2 → 6H13/2 transition can give rise to lasing action.

Dy3+-doped K2GdF5 single crystals with 10.0 mol% have been prepared by hydrothermal condition. The spectra are analyzed in term of the Judd–Ofelt theory, the intensity parameters (Ωλ, λ = 2, 4, 6) have been evaluated for Dy3+-doped K2GdF5 sample. The electric (Sed), magnetic (Smd) dipole line strength, radiative (A), and total radiative (AT) transition probabilities, lifetime (τR), branching ratios (βR) for the excited levels of Dy3+ doped K2GdF5 crystals were investigated by using the intensity parameters. In addition, the stimulated emission cross-sections (σλp) and integrated emission cross-section (Σif) have been predicted for the transitions from excited level, 4F9/2, to the 6H15/2, 6H13/2 and 6H11/2 levels. The energy transfer occurs from Gd3+ to Dy3+, resulting in the additional intense excitation UV-narrow bands for the luminescence of the Dy3+ ions.