卷 123, 编号 3-4 (2024): THEMED SECTION: STRUCTURAL DIAGNOSTICS OF MATERIALS

The peculiarities of formation and growth of crystals of linear oligophenyls (from diphenyl to p-sexiphenyl) under conditions of physical vapor transport have been investigated. Two structural variants of horizontal growth furnaces were used to study the crystal growth processes: single-zone with a gradient temperature field (classic type) and with two temperature zones. Optimal conditions for growing crystals on a scale of 0.1 to 1 cm were determined for the studied compounds. It was found that under conditions of a two-zone temperature field, at certain temperature difference values between the hot and cold zones, it is possible to obtain larger crystals of better morphological quality compared to growth under conditions of a single-zone gradient thermal field. The crystal structure of the grown single crystalline films was investigated using X-ray diffraction methods.

Mass synthesis techniques of photoluminescent β-NaRF4 (R=Y, Er–Lu) nanoparticles by utilizing “topdown” and “bottom-up” technological approaches have been optimized. Technological regimes for high-energy milling of β-NaRF4 polycrystal ingots fabricated by melt directional crystallization have been developed for the synthesis of particles in the size range up to 100 nm with a mass yield of up to 2.5 g per technological process. The subsequent heat treatment of milling nanoobjects in the presence of appropriate trifluoroacetate precursors in a high-boiling organic solvent medium significantly improves their photoluminescent characteristics due to surface passivation. The synthesis of β-NaRF4 nanoparticles by heterogeneous crystallization on ultrafine seed crystals has been developed and optimized. This technique allows to stabilize the growth process and solve the observed synthetic difficulties determined by the polymorphism of this kind of compounds. The simplicity and efficiency of the proposed technology for the mass production of β-NaRF4 nanoparticles based on “heavy” R=Yb, Lu (up to 50 g per synthesis) with a complex “seed–core–shell” structure in a broad size range with controlled morphological and structural characteristics are demonstrated in detail.

The encapsulation of riboflavin in polymer particles is a promising direction in the development of long-acting forms of riboflavin delivery. Polymorphic forms of riboflavin – type B/C and type P – are encapsulated in sodium alginate particles. When incorporated into an alginate matrix, riboflavin forms spherical agglomerates of crystals with fluorescent properties. A release study showed a prolonged release pattern for particles loaded with type P riboflavin.

The application of modern methods of materials science to cultural heritage allows us to obtain fundamentally new information about historical materials, necessary for solving both fundamental problems of history and archeology, and applied issues of preservation of cultural and historical monuments.
The proposed integrated approach to multilevel research of ceramic historical materials, based on a combination of integrated and localizing physico-chemical structural methods of materials science and developed for the study of antique ceramics. The resulting data set of macro- and micro indicators (the size and quantitative content of inclusions and pores, mineralogical and elemental composition of natural and artificial impurities etc.) allows us to identify the characteristic parameters of products from various production centers, since it contains information about the specifics of the materials used and the features of the manufacturing technology of the objects under study. This approach has shown its effectiveness for the study of not only ceramics, but also other multiphase multicomponent mineral composite materials of cultural heritage sites of various eras – in particular, medieval building ceramics (tiles), ancient Roman dishes (called terra sigillata) and medieval mortars and plasters.