Glass formation and properties of novel GeS2-Sb2S3-In2S3 chalcogenide glasses

Novel chalcogenide glasses based on GeS₂-In₂S₃-Sb₂S₃ system were prepared by conventional melt-quenching method and their physicochemical properties, e.g. glass transition temperature, density, and Vickers micro-hardness, were studied in detail. The results show that the thermal, mechanical, and optical properties depend largely on four-coordinated Ge or In entities and are sensitive to the variation of the connectivity in the GeS₂-In₂S₃-Sb₂S₃ glass network. It is a promising chalcogenide glass system suitable for rare earth doping or crystallization of rare earth doped crystals, which aims at optical applications of IR optical amplifier or efficient solid state laser.     

Phase investigations in the system PbSIn2S3 and the crystal structures of PbIn2S4 and Pb6In10S21

The system PbS-In₂S₃ was examined by differential thermal analysis (DTA), chemical vapour transport (CVT), and X-ray diffraction. Five new phases of compositions closely related to the 1:1 ratio were found and prepared as needle-shaped single-crystals; their crystal data are reported. The structures of PbIn₂S₄ (orthorhombic, Pnma, a=11.688(1), b=3.8528(1), $\text{c}\text{=13.763(1)}\text{A}\text{?}$, Z=4) and Pb₆In₁₀S₂₁ (monoclinic, C2/m, a=27.629(3), b=3.8630(5), $\text{c}\text{=15.705(2)}\text{A}\text{?}$, β=95.9°, Z=2 were solved from 808 resp. 3554 independent reflexions and refined to R=0.116 resp. 0.068. In both structures the In-S coordination polyhedra are distorted octahedra, the Pb-S polyhedra are distorted bicapped trigonal prisms.     

Die strukturen von BaGa2S4 und BaAl2S4

The isotypic compounds BaGa₂S₄ and BaAl₂S₄ crystallize in the cubic system, space group Pa3 with the constants: BaGa₂S₄: a = 1268.5±0.4 pm, BaAl₂S₄: a = 1265.0±0.7 pm. BaS₄- resp. AlS₄-tetrahedra are connected by common corners to a threedimensional net. The Ba-ions are located in holes with coordination numbers 6 resp. 12.     

Phase equilibrium and growth of homogeneous crystals in the γLa2S3  γNd2S3 system

T-x diagram of the γLa₂S₃  γNd₂S₃ system was plotted for the temperature interval 1400–2100°C. γLa₂S₃ and γNd₂S₃ form unlimited solid solutions of the substitution type. Basing on this phase diagram the theoretical distribution curves of Nd₂S₃ along the ingot of length were calculated. The experimental distribution curves were determined by chemical and electron microprobe measurements of La and Nd content in γ(La,Nd)₂S₃ ingots directionally solidified from the melt of different composition. Character of the component distribution in the ingots shows that diffusion of neodymium and lanthanum is exeptionally fast at 1700–2000°C. This phenomenon is explained by vacancy diffusion mechanism in γLa₂S₃  γNd₂S₃ solid solutions. Crystal structure of these solid solutions belongs to Th₃P₄ type with high concentration of randomly distributed cation vacancies.     

Subsolidus phase equilibria in the RuO2-Bi2O3-ZrO2 system

Subsolidus equilibria in air in the RuO₂-Bi₂O₃-ZrO₂ system were studied with the aim of obtaining information on possible interactions between a Bi₂Ru₂O₇-based cathode and a ZrO₂-based solid electrolyte in solid-oxide fuel cells (SOFCs). No ternary compound was found in the system. The tie lines are between Bi₂Ru₂O₇ and ZrO₂, and between Bi₂Ru₂O₇ and gamma-Bi₂O₃—the ZrO₂ stabilised Bi₂O₃ phase, stable at temperatures over 710 °C.     

Etude cristallographique du systeme FeSSc2S3 preparations et structures de FeSc2S4 et Fe0.85Sc2.10S4

The crystal structures of FeSc₂S₄ and Fe_0.85Sc_2.10S₄ have been determined by three dimensional X-ray diffraction. The cubic cells, space group Fd3m, have lattice constants $\text{a}\text{= 10,501}\text{A}\text{?}$ for FeSc₂S₄ and $\text{a}\text{= 10,444}\text{A}\text{?}$ for Fe_0.85Sc_2.10S₄. Iron is divalent and scandium trivalent. FeSc₂S₄ is a direct spinel structure, Fe_0.85Sc_2.10S₄ is near a spinel structure. Only 0,5 iron atom is on every 8a position; 0,175 Fe and 1,05 Sc lie on octahedral 16d and 16c site.     

Die strukturen des MgAl2S4 und Mg0.830In2.113S4

MgAl₂S₄ crystallizes in the orthorhombic system, space group Pnma (No 62) with the lattice constants: a=1251.1 ± 0.6 pm, b =722.0 ± 0.4 pm, c=592.1 ± 0.4 pm The compound is isotypic to BeAl₂O₄.Mg_0.830In_2.113S₄ forms the spinel structure, space group Fd3m (No 227) with a=1071.9 ± 0.6 pm.     

Crystal structure of cubic MnSc2S4 and Mn2.29Sc1.14S4

The crystal structure of MnSc₂S₄ ($\text{a}\text{= 10.613}\text{A}\text{?}$, space group Fd3m) and Mn_2.29Sc_1.14S₄ ($\text{a}\text{= 10.523}\text{A}\text{?}$, space groupe Fd3m) were determined by three dimensional X-Ray diffraction. MnSc₂S₄ is a normal spinel structure and the atomic distribution shows that Mn_2.29Sc_1.14S₄ structure is intermediate between the rocksalt (MnS) and the spinel (MnSc₂S₄) types. Similar behaviour of Mn and Fe atoms in MnSSc₂S₃ and FeSSc₂S₃ systems was observed.     

Comments on the system Ag2SIn2S3

The high temperature polymorph of AgInS₂ has been found to be orthorhombic with $\text{a}\text{=7.001}$, $\text{b}\text{=8.278}$, $\text{c}\text{=6.698}\text{A}\text{?}$, space group probably Pna2₁ with a distorted wurtzite structure. The phase transition temperature was found to be 620 ± 10°C and the melting point 880 ± 10°C. A new cubic spinel type phase was found at the composition AgIn₅S₈ with $\text{a}\text{=10.827}\text{A}\text{?}$.     

Zur kenntnis von Na2Cu4S3 und KCu3Te2

The crystal structures of the new compounds Na₂Cu₄S₃ and KCu₃Te₂ have been solved. Na₂Cu₄S₃ crystallizes in the K₂Ag₄S₃ structure (space group: C2/m, a = 1563(3) pm, b = 386(2) pm, c = 1033(2) pm, β = 107.6^o, N = 4), KCu₃Te₂ in the CsAg₃S₂ structure (space group: C2/m, a = 1645.3(9) pm, b = 429.4(4) pm, c = 866.1(6) pm, β = 111.86^o, N = 4).     

Preparation of ferrimagnetic SnCr2S4

SnCr₂S₄ has been prepared for the first time. It is hexagonal ($\text{a}\text{= 21.325}\text{A}\text{?}$ and $\text{c}\text{= 3.4690}\text{A}\text{?}$) and ferrimagnetic (T_C = 100 K).     

Photoluminescence spectra of MnIn2S4

MnIn₂S₄ single crystals grown by the directional crystallization method were investigated by using the temperature and excitation power dependencies of photoluminescence (PL) spectra. PL spectra consist of one broad band resulting from donor-acceptor pair recombination. The analysis of the temperature quenching of the PL intensity yields one defect donor level with a thermal ionization energy of about 0.17 eV. The broad band of PL spectra indicates that radiative recombination is related to multiphonon optical processes. The energy of the involved phonon was found to be around 0.025 eV and the energy of the acceptor level is about 0.86 eV.     

New compounds Cu2MnTi3S8 and Cu2NiTi3S8 with thiospinel structure

Cu₂MnTi₃S₈ and Cu₂NiTi₃S₈ compounds were prepared by high-temperature synthesis. The crystal structure of these quaternary phases was investigated by X-ray powder diffraction. The compounds are described in the thiospinel structure (space group ) with the lattice constants a = 1.00353(1) nm (Cu₂MnTi₃S₈) and a = 0.99716(1) nm (Cu₂NiTi₃S₈). The atomic parameters were calculated in anisotropic approximation (R_I = 0.0456 and R_I = 0.0520 for Cu₂MnTi₃S₈ and Cu₂NiTi₃S₈, respectively).     

Structure cristalline du spinelle CdEr2S4

The crystal structure of CdEr₂S₄ is solved from single crystal determinations. The R factor is 0.06 for 120 independent reflections. It is normal spinel, with regular occupancy of the sites. Interatomic distances are : 2.67 Å for ErS, and 2.57 Å for CdS.     

Topotactic redox reactions of the channel type chalcogenides Mo3S4 and Mo3Se4

Mo₃S₄ and Mo₃Se₄ were found to undergo topotactic electron-ion exchange reactions at ambient temperatures in aqueous and non-aqueous electrolytes containing transition or main group cations. The products of cathodic reduction are ternary phases A_xMo₃X₄. Mobilities of the exchangeable cations are rather high inside the solid and are responsible for high reaction rates. Cathodic reduction of Mo₃S₄ and Mo₃Se₄ represents a suitable method for the preparation of both stoichiometric and nonstoichiometric ternary phases which are of interest with respect to the superconducting properties of these chalcogenides.     

Order-disorder transition of vacancies in FeTi2S4

Vacancy-ordered FeTi₂S₄ was prepared by a prolonged heat treatment. X-ray and magnetic measurements showed the transition of vacancies to the disordered state at about 450°C. The magnetic property was antiferromagnetic, having the Nèel temperature at 138K. The increase of ferromagnetic character was associated with the disordering of vacancies.     

V2S3: Structure and thermal stability

Vanadium sesquioxide, V₂O₃, has been considered as a potential desulfurization agent for hot coal gases. The proposed process is based on the conversion of V₂O₃ to V₂S₃ via reaction with H₂S. Prompted by conflicting information in the literature on the thermodynamic stability and crystal structure of the potential desulfurization product, V₂S₃ was synthesized; its thermal stability determined using thermogravimetric analysis; and its structure studied using x-ray diffraction. In a relatively inert atmosphere, V₂S₃ commences decomposition near 270°C; in oxygen, near 240°C; and in 10% hydrogen, near 325°C. Analysis of the x-ray diffraction data from both powder and crystals indicated a large hexagonal unit cell with a = 6.634(3), $\text{c}\text{= 22.49(4)}\text{A}\text{?}$.     

Synthesis of Sb2S3 peanut-shaped superstructures

Peanut-shaped Sb₂S₃ superstructures have been synthesized via a hydrothermal process at 120 °C for 8 h using hydrochloric acid and antimony O-benzyl dithiocarbonate (benzylxanthate, Sb(S₂COC₇H₇)₃) as starting materials. The powder X-ray diffraction (XRD) pattern shows the product corresponds to the pure orthorhombic phase of Sb₂S₃, the purity and composition of which are further confirmed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies reveal that the peanut-shaped Sb₂S₃ superstructures are aggregated by nanorods. The possible mechanistic pathways in the formation of the structures are discussed.