Luminescence spectra of Ho3+ in distorted parity-breaking HoF63− octahedra

Low temperature luminescence spectrum of holmium ions in monoclinic Rb2KHoF6 crystal was found to be well analyzable by the comparison with earlier studied cubic Cs2NaHoF6. The manifestation of the local symmetry influence on the strength of individual lines is found to be distinctive. In the absence of structural data, the local symmetry of holmium in Rb2KHoF6 is proved to be a non-centrosymmetric one. The concentration quenching of holmium luminescence in Rb2KHoF6 is found to be rather modest.