Condensed Matter and Interphases

Complex copper-based chalcogenides are among the most important functional materials in modern engineering and technology due to their diverse physical and physicochemical properties, environmental safety and availability. The development of new similar materials and the improvement of the applied characteristics of known compounds is largely associated with the use of approaches based on the physicochemical analysis and, in particular, the “composition-structure-property” relationship. This review summarizes the available data on phase equilibria in ternary systems Cu-Tl(BIV, BV)-X (BIV-Si, Ge, Sn; BV-As, Sb, Bi; X-S, Se, Te) and the thermodynamic properties of their intermediate phases. Similar data are also considered for more complex systems forming solid solutions of various types of substitution based on known ternary copper chalcogenides. A significant part of the presented sets of mutually consistent data on phase equilibria and thermodynamic properties of the considered systems was obtained by our group over the past 10-15 years. Although these data cover only a small part of the systems described above, they provide great possibilities for manipulation of composition and structure, including entropic engineering strategies. The authors consider it extremely important to further develop fundamental research on phase equilibria and thermodynamic properties of complex copper chalcogenides and use their results widely in selecting alloy compositions for physical measurements

Mahammad B. Babanly

Leyla F. Mashadieva

Samira Z. Imamaliyeva

Dunya M. Babanly

Dilgam B. Taghiyev

Yusif A. Yusibov

Конденсированные среды и межфазные границы

Complex copper-based chalcogenides: a review of phase equilibria and thermodynamic properties

复杂铜基硫族化合物：相平衡与热力学性质综述

The article presents the results of many years of studies of the growth of a low-temperature modification of barium borate b-BaB2O4 (R3с) crystals in the Na, Ba, B // O, F quaternary reciprocal system. Barium borate b-BaB2O4 is the most important nonlinear optical crystal of the UV spectrum. The key factor determining the quality of crystals is the choice of an optimal solvent. The article presents phase diagrams and the results of the growth of b-BaB2O4 crystals in several subsystems of the studied quaternary reciprocal system. Using atomistic modeling, we predicted and then experimentally obtained new high-pressure modifications: g-BaB2O4 (P21/n), whose structure includes edge-sharing tetrahedra, and d-BaB2O4 with assumed symmetry Pa3. In our study, we also focused on a solid solution with an “antizeolite” structure, which also crystallizes in the Na, Ba, B // O, F system.

Tatyana B. Bekker

Nursultan E. Sagatov

Aleksey V. Davydov

Functional borates and their high-pressure polymorphic modifications. Review

功能性硼酸盐及其高压多晶型改性。综述

This paper provides a review of variants of phase diagrams of binary and ternary systems constituting the TiO2-Al2O3-SiO2-ZrO2 four-component system. The study involved building spatial (three-dimensional (3D)) computer models of the isobaric phase diagrams for four ternary oxide systems (and their variants, in case of contradicting initial data obtained by different researchers) constituting this quaternary system. The geometric structure of its phase diagram was also predicted. For this purpose, phase diagram models were constructed as geometric objects in three-dimensional (3D) or four-dimensional (4D) space in the “concentration-temperature” coordinates by assembling (hyper)surfaces (unruled and ruled) and/or phase regions.As a result:– For the TiO2-Al2O3-SiO2 system, it was considered possible variants of the structure of liquidus surfaces. These variations were due to availability of different theories describing the formation of compounds in the TiO2-Al2O3 binary system (Al2TiO5 can melt congruently or incongruently and either possesses or does not possess the property of polymorphism).– For the TiO2-Al2O3-ZrO2 and TiO2-SiO2-ZrO2 systems, 3D-models of phase diagrams were developed at temperatures above 1,280 and 1,400 °C, respectively. The temperature limits were due to the lack of definitive description of the structure of subsolidus regions in the TiO2-ZrO2 binary boundaring system.– Since the main contradictions in the ZrO2-SiO2-Al2O3 system are associated with the type of phase reaction related to zircon formation (peritectic or peritectoid), the 3D model of the phase diagram was built according to the second variant, which involved the formation of the internal field of liquidus corresponding to the primary crystallization of ZrSiO4. The structure of the phase diagrams in the subsolidus was deduced for all four systems. It was also shown that in these systems at decreasing of temperature triangulation had a place twice. For the TiO2-Al2O3-SiO2-ZrO2 quaternary system, a scheme of phase reactions with the participation of the melt was deduced. This scheme includes six five-phase invariant reactions: two peritectic, two eutectic, and two quasi-peritectic reactions

Vasily I. Lutsyk

Anna E. Zelenaya

Vera V. Vorob’eva

Phase transformations in systems formed by titanium, silicon, aluminum, and zirconium oxides: Phase diagrams prediction and modeling. Review

钛、硅、铝和锆氧化物体系中的相变：相图预测与建模。综述

The nonstoichiometry of refractory compounds with a volatile component is based on solid-phase and heterophase processes. At the same time, measurements of the parameters of these high-temperature phase transformations are often inaccurate. The inaccuracy results from the instability of the equipment as well as the behavior of themselves samples. To overcome these limitations, we developed three new methods of physicochemical analysis, which were then used in a comprehensive approach to the study of nonstoichiometry and the chemical composition of defective phases at the macro and micro levels. We refer to are high-speed thermal analysis, static tensimetric membrane technique, and stoichiographic differential dissolution method. The methods were used to measure temperatures up to 2400 °С, pressure up to 10 atm, and the degree of nonstoichiometry up to 10–4 mol. %. The review demonstrates the effectiveness of the proposed methodology applied to refractory compounds LnS, Ln2S3 (Ln = РЗМ), Yb(Ln)14MnSb11, ZrGeO4, Zr3GeO8, MgO, and Mg(Ru)O, as well as highly volatile REM polychalcogenides and ZnMo(W)O4, presented in the form of powders, large crystals, ceramics, and films. For each of the studied substances, fundamental knowledge was gained regarding their spatial-temporal evolution responsible for the occurrence and the degree of nonstoichiometry. The data was obtained by studying Т-х and р-Т diagrams and by using of the stoichiographic method to determine the phase purity, microstructural inclusions, and spatial chemical inhomogeneity of individual phases at a micro level. The obtained new quantitative thermodynamic and physicochemical data regarding the nonstoichiometry of the studied compounds was used as a basis for the choice of the composition and the design of the crystallization process, sintering and chemical deposition of thin films to realize a directed synthesis of materials with the desired properties. The review was initiated by Professor Magomed Babanly, DSc in Chemistry, Associate Member of the Russian Academy of Sciences, and editor of the special issue of the journal Condensed Matter and Interphases dedicated to physicochemical analysis in material science.

Inga G. Vasil´eva

Nonstoichiometry of refractory inorganic compounds with a volatile component determined by new methods of physicochemical analysis. Review

采用新物理化学分析方法测定含挥发性组分的难熔无机化合物的非化学计量性。综述

The review analyses and, where possible, reconciles data on two large groups of inorganic substances that are very unusual in terms of structure and properties, designated as AIIIBVI compounds. The structures and properties of typical compounds of these systems: A1IIIB1VI and A2IIIB3VI were considered. The relationship between the structure and the nature of the chemical bond and the organization of stoichiometric vacancies in crystal lattices is described in detail. The genesis of structures was analyzed for various modifications of A2IIIB3VI sesqui-chalcogenides. The transformations of these compounds into each other were also considered in relation with the ordering/disordering processes of stoichiometric vacancies. The possibilities of forming nanolayer structures, tubulenes, and intercalates were demonstrated for A1IIIB1VI layered compounds. The prospects for the application of both nanolayer coatings and bulk single crystals of A1IIIB1VI and A2IIIB3VI phases were analyzed. The presented review is based on the analysis of both literary data and the results of the studies of the authors and some other researchers of Voronezh State University

Alexander Y. Zavrazhnov

Nikolay Y. Brezhnev

Ivan N. Nekrylov

Andrew V. Kosyakov

Viktor F. Kostryukov

Phases with layered (AB) and “defective” (A2B3) structures in AIII–BVI systems Part 1. Structural uniqueness and properties of bulk samples and films. Review

AIII–BVI体系中具有层状（AB）和“缺陷型”（A2B3）结构的相 第1部分：块体样品和薄膜的结构独特性与性能。综述

The GeTe-SnTe-Bi2Te3 system is of great interest due to the potential formation of a series of cation-substituted solid solutions based on ternary layered compounds with a tetradymite-type structure, which have significant potential as valuable thermoelectric materials and topological insulators. This study presents the results of investigating this system in the composition range of GeBi2Te4-SnBi2Te4-Bi2Te3 using powder X-ray diffraction analysis. Particular attention is given to obtaining equilibrium alloys. An isothermal section of the phase diagram at 300 K has been constructed, consisting of four single-phase regions separated by three two-phase regions. The X-ray diffraction patterns of the equilibrium alloys were refined using the Rietveld method. The obtained diffraction results clearly indicate the presence of continuous series of solid solutions along the sections GeBi2Te4-SnBi2Te4, GeBi4Te7-SnBi4Te7, and GeBi6Te10-SnBi6Te10. The lattice parameters for all the solid solution series were determined, showing a linear increase with the rise in Sn concentration.

Elnur R. Nabiyev

Elnur N. Orujlu

Aytan I. Aghazade

Alakbar A. Hasanov

Магомед Баба Бабанлы

The solid-phase equilibria in the GeBi2Te4-SnBi2Te4-Bi2Te3 system at 300 K and the characterization of tetradymite-type layered solid solutions

GeBi2Te4-SnBi2Te4-Bi2Te3体系在300 K下的固相平衡及辉碲铋矿型层状固溶体的表征

The research involved synthesizing b-cyclodextrin hydrates of the b-CD·nH2O (n = 11.9–0.9) composition. The obtained compounds were studied by powder X-ray diffraction (XRD), which revealed the transition from a monoclinic unit cell to an orthorhombic one with a decrease in the water content in the samples. The pressure of saturated vapor of the water in the b-CD·nH2O (n = 10.6–7.0) hydrates was measured by static tensimetry with membrane null-manometer over a wide temperature range (293–384 K) under conditions of a quasi-constant hydrate composition. The measured vapor pressure increases in proportion to the increase in the water content of the hydrate samples. The experimental data reduced to a single composition of b-CD·1H2O were approximated by the lnp(1/T) equation, from which the thermodynamic parameters (∆prH°T and ∆prS°T) of the process of b-cyclodextrin hydrate dehydration were calculated. This information was used to estimate the binding energies of the water molecules to the b-CD framework

Lyudmila N. Zelenina

Tatyana V. Rodionova

Tamara P. Chusova

Anastasia V. Sartakova

Andrey Yu. Manakov

Physicochemical study of the processes of b-cyclodextrin hydrates dehydration

β-环糊精水合物脱水过程的物理化学研究

The article considers ternary sulfide Cu1.1Fe1.9S3 with a metal/sulfur ratio corresponding to the complete stoichiometry of cubanite CuFe2S3 as an intermediate phase of a solid solution with chemically disordered Cu and Fe cations in the ordered anionic framework. A new approach to determining the nature of the solid solution, its stability and behavior during cooled over a wide temperature and time range is suggested. To synthesize the sample, we used controlled directional solidification of a homogeneous melt with the Cu1.1Fe1.9S3 composition under quasi-equilibrium conditions and obtained a solidified zoned ingot, where the distribution of Cu, Fe, and S elements along its length was quantitatively determined. To detect small-scale structural and chemical changes, we used optical and electron microscopy methods, electron-probe X-ray spectral microanalysis, full-profile X-ray diffraction analysis, and the differential dissolution method, which allowed to determine the phase and chemical states of the samples both at the macro level and with a high spatial resolution. With this approach, we established the following: Cu1.1Fe1.9S3 is an intermediate phase of a system with end-members of cubanite CuFe2S3 and chalcopyrite CuFeS2; a homogeneous solid solution of chalcopyrite with 5 mol. % of cubanite exists near 930 °С with a chaotic distribution of Cu and Fe between the existing crystallographic positions; a solid solution of chalcopyrite with 6 mol. % of cubanite at 900 °С facilitates lattice strain relaxation through the formation of a block nanostructure; there is a solid solution of cubanite with 30 mol. % of chalcopyrite at 900–720 °С, with small-size clusters with a chalcopyrite stoichiometry evenly distributed inside the Cu0.94Fe2S3 matrix. The factors determining the evolution and stability of solid solutions are discussed taking into account the polymorphism of chalcopyrite phase. The newly obtained data is important for the synthesis of magnetic nanosized Cu-Fe sulfide materials and can also be used in the processing of sulfide ores rich in copper

Inga G. Vasilyeva

Elena F. Sinyakova

Sergey A. Gromilov

Phase transformations of ternary copper iron sulfide Cu1.1Fe1.9S3.0 under temperature variations: thermodynamic and kinetic aspects

温度变化下三元铜铁硫化物Cu1.1Fe1.9S3.0的相变：热力学与动力学研究

NaF–RF3 systems, which are composed of sodium fluorides and rare earth trifluorides, are sources of many functional materials. Data on phase formation and phase equilibria in these systems were analyzed. The polymorphism and morphotropy of rare earth fluorides were considered taking into account the influence of pyrohydrolysis. A summary series of NaF–RF3 phase diagrams are presented and the coordinates of invariant equilibria are tabulated. The data of research by Thoma et al., performed in the sixties of the twentieth century, are now only of historical interest. In these systems, a-Na0.5–xR0.5+xF2+2x (cubic, R = Pr-Lu, Y) and b-Na3xR2–xF6 (hexagonal, R = La–Lu,Y) phases of variable composition with fluorite and gagarinite structures, respectively, are formed. In addition, solid solutions based on rare earth trifluorides with the LaF3–tysonite (R = La–Gd) structure and the berthollide phase of such a structure in the system with TbF3 were identified. Data was presented on the concentration dependence of the lattice parameters of fluorite phases. High temperature a-phases with maxima on the melting curves allow growing single crystals from the melt. A complex pattern of ordering of these phases with decreasing temperature was observed. Low-temperature syntheses of intermediate phases in these systems led, in accordance with the Ostwald’s step rule, to the initial formation of nonequilibrium phases of a fluorite structure, usually designated as “a-NaRF4”, which were then replaced by equilibrium low-temperature hexagonal phases of “b-NaRF4”. The hexagonal phase in the NaF–YF3 system, doped with ytterbium and erbium (“b-NaYF4:Yb,Er”), is one of the most well-known, efficient up-conversion phosphors

Pavel P. Fedorov

Irina I. Buchinskaya

Sodium fluoride and rare earth trifluorides systems. Review

氟化钠与稀土三氟化物体系研究综述

Publication Information	Publisher: Voronezh State University，Publishing cycle: ，Journal Type: journal，Open Access Journals: Yes
Basic data	Year of publication: 2019，Proportion of original research papers: 0.00%，Self Citation Rate:N.A.， Gold OA Rate: 0.00%
Average review cycle	网友分享经验：8 Weeks

Condensed Matter and Interphases

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Complex copper-based chalcogenides: a review of phase equilibria and thermodynamic properties

Functional borates and their high-pressure polymorphic modifications. Review

Phase transformations in systems formed by titanium, silicon, aluminum, and zirconium oxides: Phase diagrams prediction and modeling. Review

Nonstoichiometry of refractory inorganic compounds with a volatile component determined by new methods of physicochemical analysis. Review

Phases with layered (AB) and “defective” (A2B3) structures in AIII–BVI systems Part 1. Structural uniqueness and properties of bulk samples and films. Review

The solid-phase equilibria in the GeBi2Te4-SnBi2Te4-Bi2Te3 system at 300 K and the characterization of tetradymite-type layered solid solutions

Physicochemical study of the processes of b-cyclodextrin hydrates dehydration

Phase transformations of ternary copper iron sulfide Cu1.1Fe1.9S3.0 under temperature variations: thermodynamic and kinetic aspects

Sodium fluoride and rare earth trifluorides systems. Review

Phases with layered (AB) and “defective” (A2B3) structures in AIII–BVI systems Part 1. Structural uniqueness and properties of bulk samples and films. Review

ISSN	1606-867X, 2687-0711
h-index	6