Eryomin O. Binary and complex fluorides of lanthanides: synthesis, structure and optical properties

The dissertation is devoted to the development of optimal synthesis methods of binary and complex fluorides of lanthanides and their systems, the study of regularities of behaviour and interaction of fluorides of lanthanides with variable degrees of oxidation at high temperatures in vacuum, in inert atmosphere, and in air, obtaining the thin-film coatings on the basis of these fluorides with high optical and operational properties and studying their optical characteristics. Synthesized binary fluorides of lanthanides in oxidation states (II) and (IV), the most suitable temperature modes and gas atmosphere for their synthesis are positioned, their thermal stability intervals have been determined. The systems EuF2 – EuF3, EuF3 – Ln'F3 (where Ln'F3 – CeF3, TbF3, PrF3), CeF3 – LnF3 (where LnF3 – YbF3, SmF3, TmF3) are researched. The formation of solid solutions based on initial fluorides in these systems is stated, the fields of stability and temperature of formation of new phases are defined. It is found that increasing temperature results in a reduction of an amount of initial phases LnF3 – Ln'F3 and formation of new phases – LnF2 – Ln'F4. The diffuse reflectance spectra of samples of the systems, calcinated at different temperatures in UV, visible, and near infrared ranges are recorded. The parameters of magnetic susceptibility are established. The investigated systems in the intensity of interaction can be placed in the following series: EuF3 – CeF3 > YbF3 – CeF3 > SmF3 – CeF3 > TmF3 – CeF3 ? EuF3 – TbF3 > YbF3 – TbF3 > SmF3 – TbF3 > EuF3 – PrF3. Optical and operational properties of the systems EuF2 – EuF3, EuF3 – CeF3 and CeF3 – YbF3 in the thin-film state are studied. It is established that the thin-film coatings produced by the method of vacuum evaporation, contain mainly a high-temperature phase ?-EuF3 and demonstrate high optical and operational properties. Keywords: fluorides, lanthanides, synthesis, structure, optical and operational properties.