Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

Структура, зеренное строение и диэлектрические свойства керамик твердых растворов YCu-=SUB=-x-=/SUB=-Mn-=SUB=-1-x-=/SUB=-O-=SUB=-3-=/SUB=-

Solid solution ceramics of the YCuxMn1-xO3 system at x = 0.05; 0.10; 0.15 were prepared by solid-phase reactions followed by sintering using conventional ceramic technology. The study of their structure, microstructure and dielectric properties including of temperature and frequencies investigation of dielectric permittivity, conductivity and tangent of dielectric loses is carried out. It is established that hexagonal phase is predominantly formed in the ceramics. Its grain structure is unhomogenius, while synthesis is performed with the formation of liquid phases of eutectic origin. It is shown that anomalous behavior of dielectric characteristics at Т=30-200 ºС connected to interlayer polarization effects, while features at Т = 222 ºС (x = 0.05), 234 ºС (x = 0.10) and 247 ºС (x = 0.15) we connected to “isostructural” phase transition that is intermediate between the ferroelectric and paraelectric phases.

Cocrystal Formation through Solid-State Reaction between Ibuprofen and Nicotinamide Revealed Using THz and IR Spectroscopy with Multivariate Analysis

Cocrystallisation can enhance the solubility and bioavailability of active pharmaceutical ingredients (APIs); this method may be applied to improve the availability of materials that were previously considered unsuitable. Terahertz (THz) spectroscopy provides clear, substance-specific fingerprint spectra; the transparency of the THz wave allows us to probe inside a sample to identify medicinal materials. In this study, THz and infrared (IR) spectroscopy were used to characterise cocrystallisation in solid-phase reactions between ibuprofen and nicotinamide. Multivariate curve resolution with alternating least squares (MCR-ALS) was applied to both time-dependent THz and IR spectra to identify the intermolecular interactions between these cocrystallising species. The analytical results revealed cocrystal formation through a two-step reaction, in which the steps were dominated by thermal energy and water vapour, respectively. We infer that the presence of water molecules significantly lowered the activation energy of cocrystal formation.

BARIUM AND STRONTIUM FERRITS SYNTHESIZED IN THE SUN FURNACE

Magnetic materials synthesized from a melt in a solar furnace were studied. It is shown that melts consist of crystallites of a metastable structure and an amorphous phase. This state contributes to a directed change in structurally sensitive properties (electrical, magnetic, and optical). It has been revealed that the magnetization values of barium and strontium ferrites synthesized from a melt in a stream of concentrated solar radiation increase 1.8 times in comparison with materials synthesized from solid-phase reactions. KEYWORDS- ferrites, magnetic material, solar furnace, structural defects, magnetization.

Rapid synthesis of cesium lead halide perovskite nanocrystals by l-lysine assisted solid-phase reaction at room temperature

By comparing three different solid-phase reactions of perovskite powder synthesized using lysine, the reaction process and properties were studied.

МОДЕЛИРОВАНИЕ ВЗАИМОДИФФУЗИИ И ФАЗООБРАЗОВАНИЯ В ТОНКОПЛЕНОЧНОЙ ДВУХСЛОЙНОЙ СИСТЕМЕ ПОЛИКРИСТАЛЛИЧЕСКИХ ОКСИДОВ ТИТАНА И КОБАЛЬТА

Предложена модель, развивающая теорию Даркена взаимной диффузии в бинарной системе с неограниченной растворимостью, на случай реакционной взаимодиффузии в двухслойной системе, состоящей из поликристаллических фаз оксидов двух металлов и содержащей подвижные и неподвижные компоненты в каждой из фаз. В рамках модели проведён численный анализ экспериментальных концентрационных распределений титана и кобальта в тонкоплёночной системе TiO2-x–Co1-yO, полученных методом резерфордовского обратного рассеяния, при отжиге в вакууме. Анализ выявил доминирующую роль диффузии подвижного кобальта в фазу TiO2-x по сравнению с диффузией подвижного титана в фазу Co1-yO и область локализации образования фаз сложных окси-дов в окрестности межфазной границы TiO2-x–Co1-yO. REFERENCES Chebotin V. N. Fizicheskaya khimiya tverdogo tela [Physical chemistry of a solid body]. M.: Khimiya Publ., 1982, 320 p. (in Russ.) Tretyakov Yu. D. Tverdofaznye reaktsii [Solid phase reactions]. M.: Khimiya Publ., 1978, 360 p. (in Russ.) Afonin N. N., Logacheva V. A. Interdiffusion and phase formation in the Fe–TiO2 thin-fi lm system. Semiconductors, 2017, v. 51(10), pp. 1300–1305. https://doi.org/10.1134/S1063782617100025 Afonin N. N., Logacheva V. A. Cobalt modifi cation of thin rutile fi lms magnetron-sputtered in vacuum technical. Technical Physics, 2018, v. 63(4), pp. 605–611. https://doi.org/10.1134/S1063784218040023 Kofstad P. Nonstoichiometry, diffusion, and electrical conductivity in binary metal oxides. Wiley-Interscience, 1972, 382 p. Smigelskas A. D., Kirkendall E. O. Zinc Diffusion in alpha brass. Trans. AIME, 1947, v. 171, pp. 130–142. Chambers S. A., Thevuthasan S., Farrow R. F. C., Marks R. F., Thiele J. U., Folks L., Samant M. G., Kellock A. J., Ruzycki N., Ederer D. L., Diebold U. Epita xial growth and properties of ferromagnetic co-doped TiO2 anatase. Appl. Phys. Lett., 2001, v. 79, pp. 3467–3469. https://doi.org/10.1063/1.1420434 Matsumoto Y., Murakami M., Shono T., Hasegawa T., Fukumura T., Kawasaki M., Ahmet P., Chikyow T., Koshihara S., Koinumaet H. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide. Science, 2001, v. 291, pp. 854–856. https://doi.org/10.1126/science.1056186 Darken L. S. Diffusion, mobility and their interrelation through free energy in binary metallic systems. Trans. AMIE, 1948, v. 175, pp. 184–190. Samarsky A. A. [Theory of difference schemes]. M.: Nauka Publ., 1977, 656 с. (in Russ.) Afonin N. N., Logacheva V. A., Gerasimenko Yu. A., Dolgopolova E. A., Khoviv A. M. Interaction of cobalt and titanium with thin fi lms of their oxides during vacuum annealing // [Condensed Matter and Interphase], 2013, v. 15 (3), p. 232-237. URL: https://journals.vsu.ru/kcmf/article/view/902/984 (in Russ.)