The Rb2Ca3(SO4)4 compound was obtained by rapid cooling of the stoichiometric melt. The crystal structure was solved and refined using single crystal X-ray diffraction analysis (P21/c, a = 9.2847(9), b = 9.4094(6), c = 9.2917(8) & Aring;, beta = 114.646(1)degrees, V = 737.80(12) & Aring;3, R1 = 0.051). The thermal behavior of Rb2Ca3(SO4)4 was investigated by high-temperature powder X-ray diffraction in the range 25-1000 degrees C. Thermal decomposition of the Rb2Ca3(SO4)4 phase occurs at 300 degrees C, forming Rb2Ca2(SO4)3 and CaSO4. The decomposition is complete at 450 degrees C, and the mixture of Rb2Ca2(SO4)3 + CaSO4 persists up to 890 degrees C. Homogenization of the phases occurs at 900 degrees C, resulting in the formation of the Rb2Ca3(SO4)4 compound again at 970 degrees C. A structural interpretation of this thermal phase transformation is presented, and the relationship between the crystal structures of Rb2Ca3(SO4)4 and Rb2Ca2(SO4)3 of the langbeinite structure type is demonstrated. Thermal expansion of Rb2Ca3(SO4)4 is highly anisotropic: alpha 11 = 23.9(4), alpha b = 19.2(3), alpha 33 = 7.7(1), alpha beta = -1.9(7), alpha V = 50.8(9) & times; 10-6 degrees C-1 at 25 degrees C and alpha 11 = -7(2), alpha b = 17(5), alpha 33 = 25(7), alpha beta = -1.1(1), alpha V = 35(9) & times; 10-6 degrees C-1 at 1000 degrees C. The anisotropy of the thermal expansion is described in comparison with the Rb2Ca3(SO4)4 crystal structure. The optical band gap for the Rb2Ca3(SO4)4 compound was determined to be 3.7 eV from absorption spectroscopy data.

Three metamict thorium orthosilicate samples from the syenite pegmatites of the Larvic Plutonic Complex, Norway, were thoroughly examined using Raman spectroscopy, electron probe microanalyses (EPMA), electron back-scatter diffraction (EBSD) and differential scanning calorimetry (DSC). Their thermal evolution upon heating was investigated using in situ powder X-ray diffraction (HTXRD) in the range of 25-1200 degrees C. One of the samples is a colour-zoned metamict thorium silicate with a preserved tetragonal shape. The zonation is due to the increasing hydration and element distribution. The EBSD indicates that the ratio of huttonite to thorite after the crystallisation significantly varies from zone to zone within the same sample. The crystallisation of thorite starts in the range of 420-480 degrees C (lower than reported previously for mineral samples), while the emergence of huttonite peaks in HTXRD patterns occurs at 870-930 degrees C. In contrast to huttonite, no thorite crystallisation peak is observed in the DSC curve. A wide temperature range is observed where both thorite and huttonite can coexist. Several fluorite-type phases form upon heating. Thorianite exists in the range of 810-1140 degrees C. After the cooling, except for huttonite and thorite, the minor crystallised phases vary and may be represented by Ca-Th oxides and rhombohedral CaUO4.The thermal expansion of the crystalline huttonite and thorite was determined as $\overline\alpha$V = 20.66 x 10-6 deg-1 for huttonite and $\overline\alpha$V = 12.54 x 10-6 deg-1 for thorite in the temperature range 25-1200 degrees C. These findings contribute to a more in-depth understanding of the behaviour of thorium orthosilicates with complex compositions, both metamict and crystalline, at elevated temperatures. They have potential applications in mineralogy, nuclear chemistry and high-level waste management.

In accordance with the developed original method of the sol-gel synthesis of compositions, based on the separate precipitation of components (using the reverse precipitation technique) followed by their mixing and sintering, ceramic composites based on the LaPO4–ZrSiO4 system are obtained. The developed sol-gel synthesis technique is based on the separate preparation of colloidal solutions of LaPO4·nH2O and zirconium hydroxide ZrO(OH)2, formed after adding ammonia solution (sols) and an alcohol solution of TEOS (gel) by reverse precipitation and subsequent mixing of the sols and gel with the addition of the ammonia solution to obtain the corresponding compositions ((1 – x)LaPO4·nH2O–x(H2SiO3‒ZrO(OH)2)) in the form of gels. The physicochemical properties of the powders are studied using the X-ray diffraction, DSC/TG, and sorption methods. The Vickers microhardness of the ceramic samples sintered in the temperature range of 1000–1300°C is measured. A Russian patent was obtained for the method of synthesizing composites based on LaPO4. Mineral-like matrices based on the LaPO4–ZrSiO4 system are intended to be used for the immobilization and disposal of individual isotopes of the actinide–rare earth fraction of high-level waste (HLW).

Nanosized (1 – x)ZrSiO4–xHf(OH)4 precursor powders are synthesized using the sol-gel method with the separate precipitation of components for obtaining (1 – x)ZrSiO4–xHfO2 ceramic composites. The thermal behavior of the precursor powders is studied using the differential scanning calorimetry and thermogravimetry (DSC/TG) method. By sintering powders precalcined at 850°C in air in the temperature range of 1000–1300°C, ceramic composites with high microhardness are obtained. The phase composition is determined by the XPA method.

Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates.

Ceramic composites (1 ‒ x)ZrSiO4‒xZrO2 with low thermal conductivity were obtained by sintering nanosized powders in the range of 1000‒1300 °C in air. The fracture surface of ceramic samples after sintering at 1300 °C was investigated and their thermal behavior was studied by dilatometry. The chemical resistance of composites by leaching in distilled water was evaluated. In the future, such ceramic composites can be used as matrices for the purpose of long-term, environmentally safe storage and subsequent final isolation from the environment of individual isotopes of actinide-rare earth fraction of high-level waste (HLW).

We report the co-precipitation synthesis and properties of nanomaterials with multilayer Aurivillius phase structures Bim+1Fem-3Ti3O3m+3 (BFTO). This paper discusses the thermal behavior of materials based on seven-layer and eight-layer compounds and presents their magnetic characteristics. The structure and morphology were characterized using PXRD, helium pycnometry, and SEM/EDX. Thermal analyses were conducted using DSC/TG. The sintering behavior was investigated through dilatometry. Mossbauer spectroscopy revealed that varying the synthesis conditions allows control over the iron distribution within the Aurivillius phase structure. Spin-phonon coupling effects were examined using Raman spectroscopy. The magnetic characteristics were assessed using vibrating-sample magnetometry. The magnetic properties were analyzed by measuring the temperature dependence of magnetization and magnetic hysteresis loops. The magnetic experiments demonstrated that the composition has a more significant impact on the BFTO magnetic response than the size effect. The results of this study suggest that the obtained materials have promising functional applications.

Single crystals of a novel silver borate nitrate, Ag-12(B9O18)(NO3)(3) (1), were produced as a byproduct upon preparation of Ag3B6O10(NO3). 1 is hexagonal, (P6(3)/m, a = 11.2896(3) & Aring;, c = 11.6693(3) & Aring;); its structure exhibits just a second example of unique [B9O18](9-) nonaborate anions [9B:6 Delta 3 square:3(<2 Delta square>-)<3 square>] which can be described as three triborate groups linked in a large cycle. As commonly observed among silver borates, the Ag+ cations exhibit strongly anharmonic vibrations which were described using Gram-Chariler series up to 4th order. 1 is characterized by single-crystal X-ray diffraction, variable-temperature powder X-ray diffraction, IR, Raman, and UV-vis-NIR spectroscopy, complex thermal analysis, and DFT calculations. The thermal expansion of 1 is slightly anisotropic (alpha(a) = 15.0, alpha(c) = 17.7 x 10(-6) degrees C-1 at 200 degrees C). Upon heating, the compound decomposes with formation of metallic silver and another borate, AgBO2, which could be earlier prepared only at high oxygen pressure.

Among germatranes, 1-germatranol hydrate is the most well-studied compound with a broad spectrum of biological activity. It is synthesized in one step by the reaction of tris(2-hydroxyethyl)amine with germanium dioxide in an aqueous medium without the use of organic solvents. Using this approach, new potentially biologically active compounds of germanium with hydroxyalkylamines and sulfonic and amino acids containing hydroxyalkyl groups were synthesized. The products were considered as new analogues of biologically active 1-germatranol hydrate. Their formation was confirmed by the results of elemental analysis, IR and NMR spectroscopy. In silico ADME and Pass analysis were used to assess the potential bioavailability and pharmacological activity profiles for new compounds. The results of in vitro study of the antiviral activity (influenza virus A/Aichi/2/68 (H3N2)) of the synthesized compounds are presented.

The metamict fergusonite-(Y) with the formula (Y0.70Ln0.20Ca0.13U0.02Th0.02)∑1.07(Nb0.72Ta0.17W0.06Ti0.04)∑1(O3.97(OH)0.11F0.08Cl0.03) · 2.12H2O from the Blyumovskaya Pit, Ilmeny Mountains (Russia) was studied by the means of high-temperature X-ray diffraction, thermal analysis, Raman spectroscopy and microprobe analysis. Thermal expansion was studied for both tetragonal (α-fergusonite) and monoclinic (β-fergusonite) polymorphs. The expansion of β-fergusonite is anisotropic and strongly negative along the α33. In contrast, α-fergusonite exhibits a relatively isotropic thermal expansion upon heating. The volume CTE (αV) for β-fergusonite varies in the range 22.87(94)–75.4(2.5) × 10–6 ºC−1, whereas α-fergusonite has αV = 32.33(57)–31.66(49) × 10-6 ºC−1 in the temperature range 850–1200 °C. After heating to 1100 °C, the mineral develops a porous texture, and the radioactivity is reduced by 37

Bismuth ferrites have attracted much attention in recent years because of the possibility of their promising practical applications in sensing systems as well as digital memory. In this study, nanocrystalline material based on bismuth ferrite with mullite-like structure was synthesized by solution combustion technique. The results of XRD confirmed the formation of a Bi2Fe4O9 orthorhombic phase with an average crystallite size 60 +/- 3 nm. The composition, morphology and porosity were characterized by SEM/EDX and helium pycnometry. The peculiarities of the material formation from the initial mixture with a glycine deficiency by subsequent calcination of the combustion product in air, were characterized by XRD, EDX and simultaneous thermal analysis. Magnetic properties of the substance were studied by Mo center dot ssbauer spectroscopy and magnetometry which showed that its magnetization is enhanced in comparing to similar materials by several times. Specific features in the Bi2Fe4O9 magnetization with changing temperature were analyzed for the first time. The photocatalytic activity of Bi2Fe4O9 during the decay of rhodamine B has been studied. It is demonstrated that the degradation of rhodamine B increased by about 70% when irradiated with visible light.

In this work, nanostructured diamond particles are considered as fillers for epoxy coatings. Nanodiamonds and a diamond charge obtained as a result of detonation synthesis from a mixture of TNT and hexogen are characterized by IR spectroscopy, scanning electron microscopy, and thermal analysis. It has been shown that nanodiamonds are characterized by thermal stability up to 450°C and increase the thermal stability of epoxy coatings. The influence of nanodiamonds and diamond charge, depending on their quantity and synthesis conditions, on the physical and mechanical properties (hardness, contact angle, adhesion, impact and bending strength) of epoxy coatings is studied. The results of a study of the anticorrosion resistance of epoxy coatings with 10 wt

The thermal behavior of aqueous sulfate NaHSO4·H2O and the product of its dehydration α‑NaHS-O4 is studied. The studies are carried out using high temperature X-ray diffraction and complex thermal analysis. Based on the data of three experiments, the temperature, nature, and sequence of phase transformations are established: NaHSO4·H2O(30–50°C) → α-NaHSO4(140–180°C) → Na2S2O7 + Na3H(SO4)2. With increasing temperature increasing in the NaHSO4·H2O structure hinge deformations occur at the level of a chain of NaO3(OH)(H2O)2 polyhedra. The anisotropy of thermal expansion is αmax/αmin = 1.9 for NaHSO-4·H2O and αmax/αmin = 1.3 for NaHSO4.

Extensive searches for new monovalent metal borates as promising nonlinear optical materials continuously provide new exciting results. Attempts to add the iodine end-member of the acentric Na3B4O7X family resulted in a compound with a complex twofold monoclinic superstructure, Na17B24O42I5. As for the lighter-halide analogies, its crystal structure is formed by a 12B:infinity(3)[3(4:2 Delta + 2T)] framework of B4O9 tetraborate groups, 4B:2 Delta 2 square:=, yet the guest metal- halide sublattice is less dense and contains 5 NaI per 6 Na2B4O7 formula units, most likely due to the large size of the iodide ion. Upon heating in the presence of excess NaI, Na17B24O42I5 converts into a simple hexagonal Na3B4O7I structure, completely analogous to Na3B4O7Br, which exists above 444 degrees C.

Thermal behavior of vergasovaite, ideally Cu3O(SO4)(MoO4), and its synthetic analog has been studied by high-temperature single-crystal X-ray diffraction in the temperature range of 300-1100 K. According to EMPA results, the empirical formulas are (Cu2.36Zn0.61)sigma 2.97O[(Mo0.91S0.08V0.04)sigma 1.03O4](SO4) for vergasovaite and Cu2.97O[(Mo0.92S0.09)sigma 1.01O4](SO4) for its synthetic analog. The mineral is stable up to 950 +/- 15 K; at 975 K, the unit-cell parameters and volume increase abruptly due to topotactic transformation of vergasovaite to cupromolybdite, Cu3O(MoO4)2. The transformation is accompanied by loss of sulfur (and excess copper) without destruction of the crystal. The thermal expansion of the vergasovaite structure is strongly anisotropic, being minimal along the [O2Cu6]8+ chains comprised of vertex-sharing OCu4 tetrahedra. This peculiar thermal behavior can be explained by the anisotropy of bond-length evolution in the Cu1O6 and Cu3O6 octahedra and the flexibility of the S-O-Cu and Mo-O-Cu bond angles. Synthetic Zn- and V-free analogs demonstrate negative thermal expansion at 425-625 K and melt at as low temperature as 700 K with no indication of transformation or recrystallization at least below 1200 K. The topotactic transformation observed in vergasovaite may have important implications for the design of novel materials and for understanding the alteration processes of copper minerals.

Aside from its economic value, davidite and its synthetic analogs may have potential applications in materials science. The unique properties of the crichtonite group minerals, including davidite-(La), make them attractive candidates for high-level waste (HLW) immobilization. We studied the thermal evolution of the metamict davidite-(La) from the Radium Hill, Australia. The investigation of the temperature-induced crystallization process was conducted, and the thermal expansion coefficients (TEC) for the recrystallized davidite (RD) were determined for the first time. Our results demonstrate that RD has relatively low TEC indicating its thermophysical stability. The following TECs of davidite- (La) for the temperature range 25–1200 °C were obtained: α a = α b = 9.96 (3) × 10–6 ºC−1; α c = 10.79 (4) × 10–6 ºC−1. The character of the thermal expansion is in agreement with the structure characterized by layers stacked along the c axis. The volume TEC αV = 24.81 (47)—36.80 (48) × 10–6 ºC−1. Davidite-(La) exhibits an almost isotropic thermal expansion and shows one of the most superior thermal performances in comparison to the other mineral-like phases utilized for the immobilization of HLW.