5d-4f luminescence of Ce3+, Gd3+ and Lu3+ in LiCaAlF6

► First observation of VUV 5d-4f luminescence of Gd3+ and Lu3+ ions doped into LiCaAlF6. ► Fine vibronic structure in the high-resolution (∼0.5 Å) VUV spectra was well resolved. ► Modeling of f-d/d-f spectra taking into account the real crystal vibrational spectrum. ► Calculated Ce3+, Lu3+ spectra in LiCaAlF6 agree qualitatively with experimental data.