Synthesis and optical properties of non-stoichiometric lanthanide (Sm, Eu, Tm, Yb) fluorides

Nonstoichiometric samarium, europium, ytterbium, and thulium fluorides were prepared by reduction of the corresponding trifluorides with the same lanthanide metal or silicon. Crystal lattice type and lattice parameters of the compounds were determined by powder X-ray diffraction. In the synthesis of ytterbium fluoride, the formation of cubic superstructure Yb₂₇F₆₄ was detected. Data reflecting the relationship between the structure and optical characteristics of the phases (IR spectra, electronic diffuse reflectance spectra) were obtained and the spectral bands were assigned.