Low-temperature infrared luminescence and high-resolution absorption spectra of undoped high-quality SiC single crystals of hexagonal modifications 4H and 6H were investigated. Narrow lines with widths less than 0.2 cm^(-1) were detected, several of which were observed for the first time. It was found that some of the lines in the 4H and 6H modifications have a similar structure, however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~ 180 cm^(-1). For the most intense quartet in the region of 1.3 μm, the energy scheme of the levels for both 4H and 6H modifications were constructed.

The work deals with the synthesis and luminescent properties of calcium fluoride doped with ytterbium (5 mol.%) and erbium (1 mol.%). For synthesis technique was used co-precipitation from aqueous solutions, which comprises reacting aqueous solutions of calcium nitrate and rare-earth elements (0.2 M) with aqueous solutions of various fluorinating agents: HF (5 vol.%) or NH4F (0.62 M) with varying methods of mixing solutions. Dropping the solution of calcium nitrate and rare earths elements into reactor with fluorinating agent named direct synthesis, dropping the fluorinating agent solution into the reactor with nitrate solutions named reverse synthesis, simultaneous dropping fluorinating agent with solutions of nitrates in water (joint synthesis). Centrifuge (8000 rpm, 5 min) and aging in during time (about 1 month) was used for separation of the precipitate from the mother solution. The resulting precipitate was washed and dried in air at 45 and 600 °C. SEM data size of the precursor particles correlate with largest coherent scattering region — 26 nm. The study determined that when using a reverse procedure the values of the energy yield is higher than the direct method of mixing. When using joint methods of synthesis and centrifugation energy yield is the highest, reaching 2.62 and 3.11 % with NH4F and HF, respectively. In summary it can be noted that in order to achieve high energy yield should be used joint mixing procedure with centrifugation.

Методом соосаждения из водных растворов синтезированы прозрачные ксерогели фторидов как гексагональной (NdF3, PrF3, CeF3, структурный тип тисонита), так и кубической (Sr0.6Y0.4F2.4, Ba4Y3F17:Bi, Ba4Y3F17:Yb, структурный тип флюорита) сингоний. По данным СЭМ, ПЭМ и АСМ установлено, что прозрачные ксерогели имеют иерархическую структурную организацию: первичные наночастицы размером 20–30 нм образуют агломераты размером около 100 нм, которые в свою очередь образуют т.н. “скелет” с множественными полостями и каналами размером до сотен нм.

Определены условия синтеза ультрадисперсных порошков составов Sr1 - xNdxF2 + x c высокой фазовой однородностью. Полученные порошки охарактеризованы методами рентгенофазового анализа и растровой электронной микроскопии. Частицы в виде ограненных нано- и микрокубов в зависимости от условий осаждения имеют размеры 30–100 нм и 0.3–2.5 мкм.