Zur Kenntnis des quaternären Systems Zn?In?S?Se Der Schnitt ZnIn2S4?Znln2Se4?In2S3?In2Se3

The Quaternary System ZnIn₂S₄? ZnIn₂Se₄? In₂Se₃? In₂S₃ The title system has been investigated on the indium rich side (ratio In/Zn ≥ 2) on samples quenched from 800°C to room temperature using x-ray methods. In this section 7 different phases could be identified the phase borders of which are given. ZnIn₂S₄-type and thiogallate type mixed crystals only show a small region of homogeneity while the monophase region of spinel type mixed crystals in the indiumsulfide rich part of the phase diagram has a larger extension. There is a new trigonal compound ZnIn₂S₂Se₂ (a_hex = 3.937, c_hex = 31.97 Å) with a large region of homogeneity. In the indiumselenide rich part there are two new phases: (i) Zn_0.4In₂Se_3.4 with unknown structure and (ii) a ternary phase of unknown structure in the system In₂S_3?xSe_x for 2.1 ≤ x ≤ 2.7.     

Zur Neuuntersuchung des Phasendiagramms InI—SnI2

Redetermination of the Phase Diagram InI—SnI₂ The phase diagram of the system InI—SnI₂ was redetermined with DTA and X-ray methods. We found that the compound given in the literature by the formula In₄SnI₆ is not formed. Instead of this a phase with lower InI content and having the composition In₃SnI₅ could be established, which crystallizes in three different low temperature polymorphs. This compound transforms to yet another, high temperature polymorph to 247^°C. Additionally a ternary compound with the formula Insn₂I₅ could be observed in the system InI—SnI₂, which has the tetragonal NH₄Pb₂Br₅ structure.     

In-situ Synthesis of the Thinnest In2Se3/In2S3/In2Se3 Sandwich-Like Heterojunction for Photoelectrocatalytic Water Splitting

The efficient utilization of solar energy for photoelectrocatalytic (PEC) water splitting is a feasible solution for developing clean energy and alleviating environmental issues. However, as the core of PEC technology, the existing photoanode catalysts have disadvantages such as poor photoelectrocatalytic conversion efficiency, low conductivity of photogenerated carriers, and instability. Here, we report the ultrathin two-dimensional sandwich-like (SW) heterojunction of In₂Se₃/In₂S₃/In₂Se₃ (SW In₂S₃@In₂Se₃) for the first time for PEC water splitting. Our findings identify the efficient separation of electrons and holes by constructing SW In₂S₃@In₂Se₃ heterojunction. The in situ synthesis of ultrathin nanosheet arrays by using surface substitution of Se atom to epitaxially grow cell In₂Se₃ maximizes the contact area of heterogeneous interface and accelerates the transmission of charge carrier. Benefitting from the unique structure and composition characteristic, SW In₂S₃@In₂Se₃ displays excellent performance in PEC water splitting. The photocurrent density of SW In₂S₃@In₂Se₃ reaches 8.43 mA cm⁻² at 1.23 V_RHE. Compared with In₂S₃, the SW In₂S₃@In₂Se₃ photoanode has nearly 12 times higher PEC performance, which represents the best performance among the In₂S₃-based photoanode heterojunction reported so far. The evolution rate of O₂ reaches 78.8 μmol cm⁻² h⁻¹, and the photocurrent has no apparent variety within 24 h.     

Ternäre Thallium-Indium-Sulfide: Eine Zusammenfassung

Ternary Thallium Indium Sulfides: A Summary Combined thermal and X-Ray analyses in the ternary system Thallium—Indium—Sulfur show, that the two binary sections Tl₂S? In₂S₃ and TlS? InS contain ternary compounds with unique crystal structures. The chemical formulas of these ternary solids are TlIn₅S₈, TlIn₃S₅, TlInS₂ and Tl₃InS₃ for the section Tl₂S? In₂S₃ and TlIn₅S₆ as well as Tl₃In₅S₈ (metastable high temperature phase) for the section TlS? InS respectively. With TlIn₅S₇ an additional ternary solid could be detected, which is located outside the two sections. It is derived from the binary mixed valence compound In₆S₇ by complete substitution of In⁺ by Tl⁺. The following ionic formulations make the mixed valence character of the ternary Thallium—Indium-Sulfides reasonable: TlIn₅S₈ = Tl⁺(In³⁺)₅(S^2?)₈, TlIn₃S₅ = Tl⁺ (In³⁺)₃(S^2?)₅, TlInS₂ = Tl⁺In³⁺(S^2?)₂, Tl₃InS₃ = (Tl⁺)₃In³⁺ · (S^2?)₃, TlIn₅S₆ = Tl⁺([In₂]⁴⁺)₂In³⁺ (S^2?)₆, Tl₃In₅S₈ = 4 × [(Tl⁺)_0,75 · (In⁺)_0,25In³⁺(S^2?)₂], TlIn₅S₇ = Tl⁺[In₂]⁴⁺ (In³⁺)₃(S^2?)₇. All compounds contain Tl⁺-ions in a characteristic “lone pair coordination” of S^2? ions. Indium atoms however occur with the oxidation numbers +2 (formal, In₂ dumb bells with covalent In? In bonding) and +3 (with In³⁺ in tetrahedral and octahedral coordination of S^2?). Chemical preparation, crystal chemistry and general properties of the ternary solids are discussed, summarized and compared to each other.     

Hydrothermal synthesis of [C6H16N2][In2Se3(Se2)]: A new one-dimensional indium selenide

A new organically templated indium selenide, [C₆H₁₆N₂][In₂Se₃(Se₂)], has been prepared hydrothermally from the reaction of indium, selenium and trans-1,4-diaminocyclohexane in water at 170 °C. This material was characterised by single-crystal and powder X-ray diffraction, thermogravimetric analysis, UV-vis diffuse reflectance spectroscopy, FT-IR and elemental analysis. The compound crystallises in the monoclinic space group C2/c (a=12.0221(16) Å, b=11.2498(15) Å, c=12.8470(17) Å, β=110.514(6)°). The crystal structure of [C₆H₁₆N₂][In₂Se₃(Se₂)] contains anionic chains of stoichiometry [In₂Se₃(Se₂)]²⁻, which are aligned parallel to the [1 0 1] direction, and separated by diprotonated trans-1,4-diaminocyclohexane cations. The [In₂Se₃(Se₂)]²⁻ chains, which consist of alternating four-membered [In₂Se₂] and five-membered [In₂Se₃] rings, contain perselenide (Se₂)²⁻ units. UV-vis diffuse reflectance spectroscopy indicates that [C₆H₁₆N₂][In₂Se₃(Se₂)] has a band gap of 2.23(1) eV.     

Ba2In2Q5 (Q = S,Se): Synthesis,Crystal Structures,Electronic Structures,and Optical Properties

Two ternary metal chalcogenides, Ba₂In₂Q₅ (Q = S, Se) were successfully synthesized by solid‐state reactions. They are isostructural and crystallize in the orthorhombic space group Pbca (no. 61). Both of them have a similar three‐dimensional (3D) framework structure, which is composed of [InQ₄] (Q = S, Se) tetrahedra that are alternatingly connected on layer in the ab plane, with Ba²⁺ cations arranged between In–S or In–Se layers for electric charge balance. The measured Raman and IR spectra show that title compounds have broad transparency range up to 20 μm. From the UV/Vis/NIR diffuse reflectance spectra, it can be seen that the bandgaps of Ba₂In₂S₅ and Ba₂In₂S₅ are 2.47 eV and 2.12 eV, which are larger than these of the calculation values (Ba₂In₂S₅, 2.362 eV and Ba₂In₂Se₅, 1.908 eV), respectively. The calculated partial densities of states indicate that the bandgaps are determined by the interaction of S‐3p and In‐5s (Ba₂In₂S₅) or Se‐4p and In‐5s (Ba₂In₂Se₅), respectively. The calculated birefringences (Δn) are about 0.03 (Ba₂In₂S₅) and 0.05 (Ba₂In₂Se₅) as the wavelength above 1 μm, respectively.     

Structural investigation of the Cu2Se-In2Se3-Ga2Se3 phase diagram, X-ray photoemission and optical properties of the Cu1−z(In0.5Ga0.5)1+z/3Se2 compounds

Structures of compounds in the Cu₂Se-In₂Se₃-Ga₂Se₃ system have been investigated through X-ray diffraction. Single crystal structure studies for the so-called stoichiometric compounds Cu(In,Ga)Se₂ (CIGSe) confirm that the chalcopyrite structure (space group I4¯2d) is very flexible and can adapt itself to the substitution of Ga for In. On the other hand a structure modification is evidenced in the Cu_1−z(In_0.5Ga_0.5)_1+z/3Se₂ series when the copper vacancy ratio (z) increases; the chalcopyrite structure turns to a modified-stannite structure (I4¯2m) when z≥0.26. There is a continuous evolution of the structure from Cu_0.74(In_0.5Ga_0.5)_1.09Se₂ to Cu_0.25(In_0.5Ga_0.5)_1.25Se₂ ((i.e. Cu(In_0.5Ga_0.5)₅Se₈), including Cu_0.4(In_0.5Ga_0.5)_1.2Se₂ (i.e. Cu(In_0.5Ga_0.5)₃Se₅). From this single crystal structural investigation, it is definitively clear that no ordered vacancy compound exists in that series. X-ray photoemission spectroscopy study shows for the first time that the surface of powdered Cu_1−z(In_0.5Ga_0.5)_1+z/3Se₂ compounds (z≠0) is more copper-poor than the bulk. The same result has often been observed on CIGSe thin films material for photovoltaic applications. In addition, optical band gaps of these non-stoichiometric compounds increase from 1.2 to 1.4 eV when z varies from 0 to 0.75.     

Electrosynthesis of a Defective Indium Selenide with 3D Structure on a Substrate for Tunable CO2 Electroreduction to Syngas

Syngas (CO/H₂) is a feedstock for the production of a variety of valuable chemicals and liquid fuels, and CO₂ electrochemical reduction to syngas is very promising. However, the production of syngas with high efficiency is difficult. Herein, we show that defective indium selenide synthesized by an electrosynthesis method on carbon paper (γ‐In₂Se₃/CP) is an extremely efficient electrocatalyst for this reaction. CO and H₂ were the only products and the CO/H₂ ratio could be tuned in a wide range by changing the applied potential or the composition of the electrolyte. In particular, using nanoflower‐like γ‐In₂Se₃/CP (F‐γ‐In₂Se₃/CP) as the electrode, the current density could be as high as 90.1 mA cm^?2 at a CO/H₂ ratio of 1:1. In addition, the Faradaic efficiency of CO could reach 96.5 % with a current density of 55.3 mA cm^?2 at a very low overpotential of 220 mV. The outstanding electrocatalytic performance of F‐γ‐In₂Se₃/CP can be attributed to its defect‐rich 3D structure and good contact with the CP substrate.     

Effects of evaporation and melting on nonstoichiometry and inhomogeneity of LiInSe<Subscript>2</Subscript> crystals

Evaporation and compositional changes of the liquids above the melting point of LiInSe₂ crystals have been characterized quantitatively by using special techniques of a rapid thermal analysis and differential dissolution. The occurrence of a liquid immiscible region in the Li₂Se-rich side of the Li₂Se-In₂Se₃ diagram and incongruent evaporation with the preferential evaporation of In₂Se₃ rising markedly above boiling point were determined from the peaks on the thermal curves and from precise control over the composition of the vapour and residual solid as a function of temperature. It was shown that both the processes could be the sources of nonstoichiometry and inhomogeneity of the LiInSe₂ crystals.     

Physicochemical study of the Sb2Se3-Ho2Se3 system

The chemical interaction in the Sb₂Se₃-Ho₂Se₃ system was studied by physicochemical analysis methods (by differential thermal, X-ray powder diffraction, and microstructural analyses and also by density and microhardness measurements). The state diagram of the system was constructed. It was found that the Sb₂Se₃-Ho₂Se₃ section is a quasi-binary section of the Ho-Sb-Se ternary system. In the system, the compound HoSbSe₃ forms, which melts incongruently at 1050 K and crystallizes in the rhombic system at the unit cell parameters a = 11.855 Å, b = 11.316 Å, c = 4.139 Å, and Z = 4 in the space group Pbnm-D _2h ¹⁶ . The solubility of solid solutions based on Sb₂Se₃ at room temperature reaches 8 mol % Ho₂Se₃, whereas solid solutions based on Ho₂Se₃ were not detected.     

Phase Equilibrium in the SeO2–Bi2O3 System

The subject of the present study is the system SeO₂-Bi₂O₃ that comprises two oxides with low melting points. All batches are thermal treatment in quartz ampoules, which are evacuated and sealed at a pressure P=0.1 Pa. On the basis of DTA (differential thermal analysis) and X-ray data, the most probable liquidus line of the system has been plotted. The eutectic composition lies about 90 mol% SeO₂,with on eutectic temperature at 230°C. Above 20 mol% Bi₂O₃ the liquidus temperature extremely increases. The formation of three compounds is proved:Bi₂Se₃O₉ and Bi₂Se₄O₁₁ are melting incongruently at 540 and 350°C respectively and Bi₂SeO₅ congruently at 915°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structural models for intergrowth structures in the phase system Al2O3-TiO2

The phase system Al₂O₃-TiO₂ was investigated in the compositional range from 48:52 to 62:38 mol% Al₂O₃:TiO₂. The samples were prepared by melting the binary oxides in an arc-imaging furnace and the obtained samples were examined by powder X-ray diffraction. The recorded powder patterns could be interpreted in terms of intergrowth structures consisting of two basic building blocks, which were deduced from the known crystal structures of β-Al₂TiO₅ and Al₆Ti₂O₁₃. The structure of a new ordered compound with the formula Al₁₆Ti₅O₃₄ is proposed. The thermal stability was estimated from DTA and tempering experiments and showed that all prepared samples decompose at temperatures around 800 °C into the binary oxides corundum and titania.     

Phase diagram of the In3As2Se6-In3As2S3Se3 system

The In₃As₂Se₆-In₃As₂S₃Se₃ system has been investigated by methods of physicochemical analysis (DTA, X-ray powder diffraction, MSA) and by microhardness and density measurements. The phase diagram of the system, which is the quasi-binary section of the As-In-S-Se quaternary system, has been constructed. The region of the In₃As₂Se₆-based solid solutions is extended to 7 mol %, and the In ₃As₂S₃Se₃-based region to 15 mol %. A new quaternary compound In₆As₄S₃Se₉ is found in the system. Original Russian Text ? I.I. Aliev, R.S. Magammedragimova, A.A. Farzaliev, Dzh. Veliev, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 4, pp. 691–694.     

Thermal stability of In2(MoO4)3 and phase equilibria in the MoO3–In2O3 system

Thermal stability of a compound forming in a binary system MoO₃?CIn₂O₃ was investigated by DTA/TG, XRD and SEM methods in this study. For the first time, the diagram of phase equilibria established in the whole range of concentrations of this system's components has been constructed. The temperature and concentration ranges of the components of MoO₃?CIn₂O₃ system in which the compound In₂(MoO₄)₃ co-exists in solid state with MoO₃ or In₂O₃ or with the liquid were determined. The composition and melting point of the eutectic mixture consisting of In₂(MoO₄)₃ and MoO₃ were found.     

Phase Instability in van der Waals In2Se3 Determined by Surface Coordination

van der Waals In₂Se₃ has attracted significant attention for its room-temperature 2D ferroelectricity/antiferroelectricity down to monolayer thickness. However, instability and potential degradation pathway in 2D In₂Se₃ have not yet been adequately addressed. Using a combination of experimental and theoretical approaches, we here unravel the phase instability in both α- and β′-In₂Se₃ originating from the relatively unstable octahedral coordination. Together with the broken bonds at the edge steps, it leads to moisture-facilitated oxidation of In₂Se₃ in air to form amorphous In₂Se_3−3xO_3x layers and Se hemisphere particles. Both O₂ and H₂O are required for such surface oxidation, which can be further promoted by light illumination. In addition, the self-passivation effect from the In₂Se_3−3xO_3x layer can effectively limit such oxidation to only a few nanometer thickness. The achieved insight paves way for better understanding and optimizing 2D In₂Se₃ performance for device applications.     

Dipotassium Sodium Diantimonidoindate,K2Na[InSb2], a compound with the polyanion [In2Sb2Sb4/2]6−

The novel compound K₂Na[InSb₂] was synthesized from the elements at 900 K in sealed niobium ampoules. The compound forms plate-like crystals with silver metallic luster, which are very unstable in air and moisture. The crystal structure of K₂NaInSb₂ has been determined using single-crystal X-ray diffraction methods (space group Cmca (No. 64); a = 14.032(2), b = 16.399(3), c = 7.009(1) Å; Z = 8; Pearson symbol oC48). The structure contains pairs of edge-sharing InSb₄ tetrahedra which are linked to four other pairs via common vertices and form a two-dimensional [In₂Sb₂Sb_4/2]^6? anionic partial structure. The resulting pairs of tetrahedral holes are filled by Na⁺ cations. These [In₂Sb₂Sb_4/2]^6? layers are stacked along the b-axis and are interconnected by K⁺ cations. The whole structure can be considered as an ordered derivative of the KMnP structure (PbFCl type).     

Schichtanionen in den Kristallstrukturen der isotypen Verbindungen Sr2[Ga2S5], Ba2[In2S5] und Ba2[In2Se5]

Layer-Anions in the Crystal Structures of the Isotypic Compounds Sr₂[Ga₂S₅], Ba₂[In₂S₃], and Ba₂[In₂Se₅] The compounds Sr₂[Ga₂S₅], Ba₂[In₂S₅], and Ba₂[In₂Se₅] have been prepared from stoichiometric mixtures of the elements at temperatures between 1150°C and 1250°C. They are isotypic (space group Pbca, Z = 8) with the lattice constants see ?Inhaltsübersicht”?. In the anionic part of the structure GaS₄-(InS₄-/InSe₄)-tetrahedra share three common vertices to form layers with rings built by four and eight tetrahedra. The cations are placed between the sheets and have the coordination number seven.     

Zur Neuuntersuchung des Phasendiagramms TlI—SnI2

Redetermination of the Phase Diagram TlI—SnI² A reinvestigation of the phase diagram TlI—SnI₂ revealed the existence of a not yet known ternary 4 : 1 compound of the formula Tl₄SnI₆, which decomposes peritectoidally at 229^°C. The congruent melting points of the other three ternary compounds in the system, Tl₃SnI₅, TlSnI₃, and TlSn₂I₅, at 329^°C, 292^°C and 307^°C, respectively, agreed well with former specifications. However the polymorphic transitions of the compounds Tl₃SnI⁵ and TlSn₂I₅ described by other authors could not be verified.     

Eine neue metastabile Verbindung mit eigenem Strukturtyp: BaNi2In8O15

A New Metastable Compound with a Hitherto Unknown Structure Type: BaNi₂In₈ O₁₅ A new metastable compound: BaNi₂In₈O₁₅ was prepared by high temperature technique and investigated by X-ray single crystal studies. It crystallizes with orthorhombic symmetry, space group D_2h¹⁸–Cmca (a = 12.2811, b = 11.0214, c = 9.9103 Å; Z = 4). A typical feature of the metastable property of BaNi₂In₈O₁₅ is the statistical occupation of one of the point positions with In³⁺ and Ni^2? ions. The structure, especially the InO₆/NiO₆-octahedral network are shown and discussed in respect to the metastable behavior of BaNi₂In₈O₁₅.     

Interaction in the TlSe-Pr2Se3 system

The interaction of components in the TlSe-Pr₂Se₃ system was studied by differential thermal, X-ray powder diffraction, and microstructural analyses and also by microhardness and density measurements. The state diagram of this system was constructed. It was found that the section TlSe-Pr₂Se₃ is a quasi-binary section of the Tl-Pr-Se ternary system. In the TlSe-Pr₂Se₃ system at the component ratio 1: 1, a new chemical compound, TlPr₂Se₄, forms, which melts congruently at 1295°C. In the system based on TlSe, solid solutions form until 3.5 mol % Pr₂Se₃, and in the system based on Pr₂Se₃, solid solutions occur until 2.5 mol % TlSe.