Phase transformations in LnF3-(Ln, Zr)-ZrF4 systems, where Ln = Sm, Eu, Tm, Yb

Phase transformations in LnF₃-(Ln, Zr)-ZrF₄ systems (where Ln = Sm, Eu, Tm, Yb) in the temperature range 700-900 °C have been investigated by chemical and X-ray phase analyses, UV and IR spectroscopy. Synthesis conditions of nonstoichiometric samarium, europium, ytterbium and thulium fluorides, which are products of interaction between LnF₃ and Ln and original substances for the preparation of compounds such as LnZrF₆ are given. The crystal lattice of the fluorozirconates obtained is similar to the Yb₂₇F₆₄ superstructure. Thulium fluorozirconate (TmZrF₆), whose structure is indexed as the Tm₁₃F_32−δ superstructure of hexagonal system, is an exception. For all compounds obtained, the lattice parameters have been calculated and the absorption bands of IR spectra have been interpreted.