The temperature dependence of the heat capacity of Y2Ti2O7 and Eu2Ti2O7 with a pyrochlore structure in the temperature range of 7–1800 K has been studied. The existence of a small shallow anomaly of the heat capacity of europium titanate in the range of 10–60 K was confirmed. The thermodynamic properties (entropy, enthalpy change, and reduced Gibbs energy) were calculated. Based on the results of calculation of the Gibbs energy of formation of the titanates from oxides it was concluded that both titanates are thermodynamically stable in the high temperature region.

The specific magnetization and magnetic susceptibility of ferrogarnets of the composition Y3–xCex(Fe0.5Ga0.5)5O12 (x = 0; 0.5) obtained by the gel combustion method have been measured. It has been found that after synthesis and subsequent crystallization at pressure ≈ 10–2 Pa at 1023 K for 2 h, the temperature of magnetic phase transformation in the studied compositions Y3–xCex(Fe0.5Ga0.5)5O12 increases with the replacement of yttrium ions Y3+ by Ce3+. In this case, the effective Curie–Weiss temperature Ɵeff of the antiferromagnetic component of exchange magnetic interactions in Y2.5Сe0.5Fe2.5Ga0.5O12 varies from |–570| to |–650| K.

Modern otology faces challenges in treating tympanic membrane (TM) perforations. Instead of surgical intervention, alternative treatments using biomaterials are emerging. Recently, we developed a robust collagen membrane using semipermeable barrier-assisted electrophoretic deposition (SBA-EPD). In this study, a collagen graft shaped like a sponge through SBA-EPD was used to treat acute and chronic TM perforations in a chinchilla model. A total of 24 ears from 12 adult male chinchillas were used in the study. They were organized into four groups. The first two groups had acute TM perforations and the last two had chronic TM perforations. We used the first and third groups as controls, meaning they did not receive the implant treatment. The second and fourth groups, however, were treated with the collagen graft implant. Otoscopic assessments were conducted on days 14 and 35, with histological evaluations and TM vibrational studies performed on day 35. The groups treated with the collagen graft showed fewer inflammatory changes, improved structural recovery, and nearly normal TM vibrational properties compared to the controls. The porous collagen scaffold successfully enhanced TM regeneration, showing high biocompatibility and biodegradation potential. These findings could pave the way for clinical trials and present a new approach for treating TM perforations.

To maintain the single-phase nature of the cubic solid solution Ba2(Y, Cu, Mo)2O6, which is prone to polymorphism, titanium oxide was used. As a result of the synthesis by gel burning, annealing at 1000°C, and subsequent cooling in an inertial thermal mode, the cubic modification F 4̅ 3m of Ba5Y2CuMoTiO14 was obtained for the first time without an admixture of perovskite Fm3m. A comparative study of samples Ba4Y2CuMoO11 and Ba5Y2CuMoTiO14 was carried out using X-ray powder diffraction, X-ray fluorescence spectrometry, IR spectroscopy, and diffuse reflectance spectroscopy.

The heat capacity of LaMgAl11O19 with a magnetoplumbite structure was measured in the temperature range of 7–1865 K using relaxation, adiabatic, and differential scanning calorimetries. The obtained temperature dependences of the heat capacity are consistent based on adiabatic calorimetry data. Thermodynamic functions (entropy, enthalpy change, and reduced Gibbs energy) in the range 0–1865 K were calculated from fitted values. By using high-temperature X-ray diffraction, thermal expansion in the range of 300–1200 K was studied and the coefficient of thermal expansion of LaMgAl11O19 was calculated.

A two-component magnetodielectric coating has been obtained based on an organic matrix, namely, photoresist of the FP-9120 series, into which powder Mg(Fe0.7Ga0.3)2Ox has been uniformly incorporated. The coating is characterized by the preservation of the properties of the original components and the uniform distribution of particles. The coating possesses phase stability and stable magnetic properties, which allows it to be used in the microwave region with low losses.

This work reports on the possibility of producing oxide InGaMgO4 by two-stage heat treatment of glycine-, starch- and PVA-nitrate precursors. The products formed as a result of their heating at low temperatures (≈ 90°С) were studied by powder X-ray diffraction. It was found that the powder formed from the glycine-nitrate precursor contains nanocrystalline In2O3, and drying of the polymer-nitrate compositions leads to the production of a thermally stable X-ray amorphous product. Its annealing at temperatures above 800°C allows synthesizing powder InGaMgO4 free of impurity phases. High-temperature treatment of the powder formed from the glycine-nitrate precursor also leads to the production of InGaMgO4, but does not remove the In2O3 impurity. Using scanning electron microscopy, it was found that single-phase InGaMgO4 powders synthesized from polymer-nitrate precursors have a similar grain structure but differ in grain size distribution. Presumably, this difference is due to the structural features of starch and PVA macromolecules used for the preparation of precursors. Oxide InGaMgO4 was characterized using differential scanning calorimetry, Raman and diffuse reflectance spectroscopy. The value of its band gap energy Eg was determined using the Tauc method.

The ionic composition of ferrogranate powder samples of composition Y2.5Ce0.5Fe2.5Ga2.5O12 obtained by gel combustion followed by crystallization at 750°С in a furnace for 5 h at a pressure of ≈ 1 × 10–2 Pa has been studied by XANES method. The results are compared with the X-ray powder diffraction and X-ray photoelectron spectroscopy (XPS) data obtained by the authors earlier. It is shown that according to X-ray powder diffraction data, ferrogranate Y2.5Ce0.5Fe2.5Ga2.5O12 is single-phase, but according to the results of XANES and XPS, spectroscopy along with Ce3+ in the sample Ce4+ is present both in the volume and on the surface of crystallites.

A new phase Ba2(Y,Cu,Mo)2O6 with the cubic perovskite structure Fm-3m has been obtained in the BaO–CuO–Y2O3–MoO3 quasiquaternary system, and the possibility of coexistence of two limited solid solutions with cubic structures Fm-3m and F-43m has been established. The samples were synthesized by gel combustion followed by calcination at 1000°C and cooling in the inertial thermal regime. The studies were carried out by X-ray phase analysis, X-ray fluorescence spectrometry, infrared spectroscopy, and diffuse reflectance spectroscopy.

Lutetium stannate with a pyrochlore structure was synthesized using solid state reaction. The heat capacity of polycrystalline Lu2Sn2O7 in the temperature range of 7.99–1871 K was measured by adiabatic and differential scanning calorimetry methods. Entropy, enthalpy change, and derived Gibbs energy were calculated from the smoothed heat capacity data. The Gibbs free energy of Lutetium stannate from elements was estimated, using the ΔfS°(Т) values obtained in this work and the ΔfH°(Т) values known from the literature. The temperature dependence of the cubic crystal lattice parameter and the value of the coefficient of thermal expansion in the temperature range of 300–1273 K were determined by high-temperature X-ray diffraction.

Phase equilibria in CaCl2–CaCl2⋅4CO(NH2)2–H2O system sections are studied at temperatures from 0 to –55°C. The earlier hypothesis that the formation of a low-temperature eutectic (–55°C) in the system is caused by CaCl2⋅4CO(NH2)2 is confirmed. A number of low-temperature eutectic mixtures promising for the development of anti-icing reagents on their basis are revealed.

Polycrystalline samples of the pseudobinary system Ba2YMoO6–[Ba2YCuO5] were synthesized using the gel combustion method. The obtained samples were investigated using X-ray diffraction and photoluminescence spectroscopy. The substitution of Mo with Cu led to the stabilization of cubic phases Fm3̅m and F4̅3m of the solid solution Ba2YMo1 – xCuxO6 – δ (0 ≤ x ≤ 0.5) in air.

Samples of Mg3 – nNinBPO7 (n = 0–3), synthesized by gel combustion followed by annealing at 980°C and cooled in the inertial-thermal mode, were studied by X‑ray powder diffraction, infrared spectroscopy, and X-ray fluorescence spectrometry. For the first time, the crystalline phase of Ni3BPO7 with the β-Zn3BPO7 structure has been experimentally obtained. When the composition of the samples changed from Mg3BPO7 to Ni3BPO7, a region of coexistence of α‑Mg3BPO7 and β-Ni3BPO7 phases was found. An analysis of the diffuse reflectance spectra of the Mg1.5Ni1.5BPO7 sample showed the presence of Ni2+ cations in an arrangement not symmetric octahedral or tetrahedral.

The main goal of this study is the preparation of single-phase MgFe2O4 and Mg(Fe0.8Ga0.2)2O4 powders using a gel auto-combustion method. X-ray powder diffraction (PXRD), micro-X-ray fluorescence spectrometry (μ-XRF), CHNS elemental analysis, scanning and transmission electron microscopies (SEM and TEM) methods have been used to characterize morphology and chemical composition of the synthesized sample. The cationic distribution in the ferrites has been evaluated from the 57Fe Mössbauer spectroscopy measurements. Mössbauer measurements were used to characterize the paramagnet-ferrimagnet phase transition in MgFe2O4.

X-ray powder diffraction, X-ray photoelectron, and Mössbauer spectroscopy are used to study the ionic and phase compositions of samples of powdered ferrogarnet Y2.5Ce0.5Fe2.5Ga2.5O12 obtained by gel combustion followed by crystallization in vacuum and additional annealing in air at 750°С. According to X-ray photoelectron and Mössbauer spectroscopy data, the iron and cerium cations in the homogeneous ferrogarnet structure are stabilized in the formal oxidation state Fe3+. At the same time, along with Ce3+, the surface of Y2.5Ce0.5Fe2.5Ga2.5O12 particles contains Ce4+ ions. The results obtained can be used to create functional materials for a new generation of magnetooptical devices.

— Using LaBWO 6 as a host, we have prepared a series of erbium-doped lanthanum borotungstates (LBTs), La 1 – x Er x BWO 6 , and Yb/Er-codoped La 1 – x – y Yb x Er y BWO 6 , which crystallize in monoclinic crystal system (sp. gr. P 2 1 ). The materials have been synthesized by ceramic route and a sol–gel (Pechini) process, followed by annealing. We have studied the spectral properties of the synthesized LBTs exhibiting the luminescence in the green spectral region upon the excitation in the near-infrared region. The highest efficiency, with B en = 0.55%, has been obtained for La 0.97 Yb 0.02 Er 0.01 BWO 6 composition. Sol–gel synthesis (Pechini process) has been shown to be the optimal approach for the preparation of such phosphors. Due to a combination of high upconversion efficiency and thermal stability, the synthesized upconversion phosphors can be used for the design of white light sources pumped in the near-IR spectral region.

Mg 3 – n Ni n BPO 7 samples ( n = 0–3) were synthesized by gel combustion followed by annealing at 980°C, cooled under inertial-thermal conditions, and then studied by X-ray powder diffraction analysis, IR spectroscopy, and X-ray fluorescence spectrometry. A crystalline phase of Ni 3 BPO 7 with the β-Zn 3 BPO 7 structure was experimentally obtained for the first time. When varying the composition of the samples from Mg 3 BPO 7 to Ni 3 BPO 7 , in borophosphate, a region of coexistence of α‑Mg 3 BPO 7 and β-Ni 3 BPO 7 was discovered. Analysis of diffuse reflectance spectra of Mg 1.5 Ni 1.5 BPO 7 showed the presence of Ni 2+ cations in an environment different from the symmetrical octahedral or tetrahedral environment.

На основе матрицы LaBWO 6 получены серии боратовольфраматов лантана (БВЛ), допированных эрбием La 1 – x Er x BWO 6 и содопированных Yb–Er La 1 – x – y Yb x Er y BWO 6 , которые кристаллизуются в моноклинной сингонии, пр. гр. P 2 1 . Синтез проводили керамическим и золь–гель (Печини) методами с последующим отжигом. Исследованы спектрально-люминесцентные свойства синтезированных БВЛ, которые при возбуждении в ближней инфракрасной области люминесцируют преимущественно в зеленой области спектра. Наиболее высокая энергетическая эффективность была получена для состава La 0.97 Yb 0.02 Er 0.01 BWO 6 и составила B en = 0.55%. Показано, что оптимальным для получения люминофоров является золь–гель-синтез (метод Печини). Синтезированные ап-конверсионные люминофоры, обладающие высокой энергетической эффективностью и термостабильностью, могут использоваться для создания источников белого света с накачкой в ближней ИК-области.

A series of single-phase lanthanum-gadolinium germanate borates (LGGBs) La3Gd11 ‒ x ‒ yYbxEryGe2B6O34 co-doped with Yb3+ and Er3+ ions, which are promising for the development of up-conversion phosphors in the visible range, has been prepared by coprecipitation followed by annealing of the intermediates. Morphology of the prepared LGGBs has been determined by SEM. The luminescence spectra of LGGBs under infrared (IR) laser excitation (λ = 974 nm) have been recorded, and the effect of the concentration of the sensitizer (Yb3+) and luminescence activator (Er3+) on the energy yield of up-conversion luminescence has been studied. The concentration of active ions in the composition of LGGBs has been monitored by inductively coupled plasma atomic emission spectroscopy (ICP AES). It is shown that the Yb3+/Er3+ ratio optimal for obtaining the brightest phosphors is 7 : 3. The influence of the temperature of final annealing on the luminescent properties of the prepared LGGBs has been determined.

Samples of the composition Ce 0.9 (Mg 1 – x Ni x ) 0.1 O 2 (0 ≤ x ≤ 1, step x = 0.1) have been obtained by gel combustion followed by hydrothermal treatment. X-ray powder diffraction data have showed that after gel combustion and annealing at 1100°C, composite CeO 2 (fluorite structure)/solid solution Mg 1 – x Ni x O (halite structure) is formed, and additional hydrothermal treatment followed by annealing promotes the formation of limited solid solution Ce 0.9 (Mg 1 – x Ni x ) 0.1 O 2 . According to the results of IR spectroscopy, the CeO 2 /Mg 1 – x Ni x O composite does not adsorb CO 2 even in the presence of water vapor, which is also confirmed by diffuse reflectance spectra in the UV-visible region. On the contrary, the Ce 0.9 (Mg 1 – x Ni x ) 0.1 O 2 solid solution absorbs CO 2 , as evidenced by the results of IR spectroscopy and thermogravimetric analysis.