- Crystal structure and physical properties of Ba2Nb3S8I: A new misfit-layered transition-metal dichalcogenide superconductor
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Single crystals of Ba2Nb3S8I have been grown using iodine-vapor transport in fused-quartz tubes. The crystals form as flakes with typical areas of 5–10 mm2 and thicknesses of 5–11 μm. The crystal structure was determined using single-crystal x-ray diffraction with the aid of an APEX II CCD diffractometer. The structure shows trigonal symmetry with space group P31c and lattice parameters a = b = 10.0156(5) ? and c = 25.1414(15) ?. Compositional analysis via x-ray spectroscopy confirms the presence of iodine. Superlattice reflections are evident in x-ray precession images. Measurements of the electrical resistivity reveal a metallic temperature dependence and superconductivity near 1 K. Polycrystalline samples of Ba2Nb3S8I were made in order to have samples large enough for other bulk physical properties measurements. Magnetic susceptibility reveals antiferromagnetism below 275 K. The coexistence of antiferromagnetism and superconductivity is surprising. Specific heat measurements reveal the electronic coefficient γ = 3.95(66) mJ/mol K2. The jump in the specific heat at the superconducting transition temperature Tc (ΔC/γTc = 1.4(2)) and the energy gap associated with the superconducting state (Eg = 0.405(17) meV) agree well with BCS theory.
- Baker, Mitchell T.,Benjamin, S. M.,Lin, Qisheng,Neumeier, J. J.,Smith, M. G.
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- High pressure phase of Ba2FeS3: An antiferromagnet with one-dimensional spin chains
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In this work, we report on the discovery of the high-pressure phase of Ba2FeS3 with quasi one-dimensional (1D) spin chains, which was synthesized under high-pressure and high-temperature conditions. A systematic study was carried out via structural, transport, magnetic and thermodynamic measurements. The high-pressure phase of Ba2FeS3 (denoted by Ba2FeS3 (HP)) crystallizes in a K2AgI3-typed orthorhombic structure with the space group of Pnma (62) and the lattice parameters of a = 8.6831 (1) ?, b = 4.2973 (1) ?, and c = 17.0254 (2) ?, respectively, which consists of chains of corner-sharing FeS4 tetrahedra along the b axis. Ba2FeS3 (HP) undergoes a long-range antiferromagnetic transition at TN ～56 K, above which the magnetic susceptibility curve exhibits a round hump behavior with the maximum temperature Tmax ～110 K. In addition, the intrachain coupling Jintra is about ?18 K obtained by using the Wagner-Friedberg model. The specific heat data suggest that the total magnetic entropy change ΔS caused by the long-range ordering transition is only ～20% of the expected value for a S = 2 system. For comparison, the properties of K2CuCl3-typed Ba2FeS3 with similar quasi 1D spin chains were presented as well. Our results indicate that both compounds exhibit a typical feature expected for compounds with 1D spin chains.
- Duan, Lei,Zhang, Jun,Wang, Xiancheng,Zhao, Zhiwei,Xiao, Changjiang,Li, Xiang,Hu, Zhiwei,Zhao, Jianfa,Li, Wenmin,Cao, Lipeng,Dai, Guangyang,Ren, Chongwen,He, Xin,Yu, Runze,Liu, QingQing,Tjeng, Liu Hao,Lin, Hong-Ji,Chen, Chien-Te,Jin, Changqing
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- Thermal reduction of barium sulphate with carbon monoxide-A thermogravimetric study
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The kinetic parameters of the reduction of barium sulphate to barium sulphide using carbon monoxide fractions of 2.4-9.6% and temperatures of 850-1000 °C, using an isothermal thermogravimetric method, were obtained. This reaction has shown to be temperature and carbon monoxide concentration dependent. By variation in temperature, at constant CO fractions, an average activation energy of 149 (±10) kJ/mol was observed. By changing the CO fraction at constant temperature, it is suggested that the reduction reaction is first order in CO. An overall reaction rate equation is proposed.
- Hlabela,Neomagus,Waanders,Bruinsma
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- Synthesis, Structure, and Optical Properties of Antiperovskite-Derived Ba2MQ3X (M = As, Sb; Q = S, Se; X = Cl, Br, I) Chalcohalides
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Six isostructural antiperovskite-derived chalcohalides, Ba2MQ3X (M = As, Sb; Q = S, Se; X = Cl, Br, I), crystallizing in the space group Pnma, have been synthesized by solid-state reactions. The crystal structure features a 3D framework with the [XBa5]9+ disordered square pyramids as building blocks and [MQ3]3- units filling the interspace. [XBa5]9+ disordered square pyramids are edge-sharing along [010], derived from the fusing of the two pyramids in octahedral [XBa6]11+. Surprisingly, Ba2AsS3X (X = Cl, Br, I) show almost the same optical band gap of 2.80 eV, and Ba2AsSe3X (X = Br, I) also have a similar band gap of 2.28 eV. The optical band gap of Ba2SbS3I is 2.64 eV. First-principles calculations reveal that the optical absorption is attributed to the transitions between Q np at the valence band maximum (VBM) and M np-Q np at the conduction band minimum (CBM). These compounds also possess interesting photoluminescence properties with splitting emission peaks on excitation at 200 nm.
- Wang, Ruiqi,Zhang, Xian,He, Jianqiao,Bu, Kejun,Zheng, Chong,Lin, Jianhua,Huang, Fuqiang
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- Structure of Ba2Cu3 S2[VS4], a new alkaline-earth copper thiovanadate
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The new barium copper(I) sulfide tetrathiovanadate(V), Ba2Cu3S2[VS4], was obtained as a by-product of the reaction of BaS with sulvanite (Cu3VS4). The compound crystallizes monoclinically in the space group C2/c (No. 15), with four formula units in the unit cell, a=15.135(2) A, b=8.930(1) A, c=10.738(2) A and β=133.73(1)○. In the structure, infinite double-chains of condensed CuS4 and VS4 tetrahedra are running along [001]. The barium cations are located between the chains at the centers of tricapped trigonal prisms of sulfur atoms.
- Mujica,Ulloa,Llanos,Peters,Peters,Von Schnering
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- OPTICAL PROPERTIES OF ALKALINE-EARTH CHALCOGENIDES. II. VACUUM ULTRAVIOLET REFLECTION SPECTRA IN THE SYNCHROTRON RADIATION REGION OF 4-40 ev.
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The reflectivity spectra have been measured on single crystals of CaO, CaS, SrO, SrS, SrSe, BaO, BaS and BaSe in the synchrotron radiation region of 4-40 ev. In order to prevent surface deterioration effect, all measurements have been made at 77 K on the fresh (100) surfaces cleaved within a high vacuum. From a chemical trend of the spectra, the observed spectral features are classified into two groups, the interband and band-exciton transitions in the lower energy regions, and the core-excitons in the higher energy region.
- Kaneko,Morimoto,Koda
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- Vertex-linked ZnO2S2 tetrahedra in the oxysulfide BaZnOS: A new coordination environment for zinc in a condensed solid
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The wide-band-gap semiconductor BaZnOS adopts a high-symmetry modification of the SrZnO2 structure type and contains layers of vertex-linked ZnO2S2 tetrahedra, which represent a novel coordination environment for zinc in the solid state. BaZnOS: orthorhombic, space group Cmcm; a = 3.9619(2) A, b = 12.8541(7) A, c = 6.1175(4) A, Z = 4. Diffuse-reflectance spectroscopy measurements reveal a direct band gap of 3.9(3) eV, consistent with the white color and the results of band structure calculations. The band gap is larger than those observed in ZnO and ZnS, consistent with the more ionic nature of BaZnOS. Attempts to dope this compound electronically have so far not proved possible.
- Broadley, Sarah,Gal, Zoltan A.,Cora, Furio,Smura, Catherine F.,Clarke, Simon J.
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- Synthesis and characterization of two lead-containing metal chalcogenides: Ba5Pb2Sn3S13 and Ba6PbSn3Se13
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Two new metal chalcogenides, Ba5Pb2Sn3S13 (BPSS) and Ba6PbSn3Se13 (BPSSe), were successfully synthesized in vacuum–sealed silica tubes for the first time. Both of them are isostr
- Abudurusuli, Ailijiang,Ding, Hanqin,Wu, Kui
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- Catalytic effect of zinc oxide on the reduction of barium sulfate by methane
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Reduction of barium sulfate by methane was investigated in this work. The thermogravimetric method was used to obtain kinetic parameters of the reaction in the temperature range of 900-975 °C at atmospheric pressure. The kinetics of the reaction has been studied both in the absence and presence of zinc oxide as a catalyst. The conversion-time data have been interpreted by using the grain model, and the effect of catalyst on the kinetic parameters has been elucidated. It was found that zinc oxide acted as fairly strong catalyst for the reaction, especially at higher temperatures. At about 975 °C the reaction rate constant was increased more than 7 times by using 2% of zinc oxide. This enhancement in the rate constant is valuable for industries.
- Alizadeh,Jamshidi,Ale Ebrahim
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- Layered compounds BaM2Ge4Ch6 (M = Rh, Ir and Ch = S, Se) with pyrite-type building blocks and Ge-Ch heteromolecule-like anions
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The structures and chemical features of layered compounds BaM 2Ge4Ch6 (M = Rh, Ir; Ch = S, Se) synthesized by high-pressure and high-temperature methods have been systematically studied. These compounds crystallize in an o
- Lei, Hechang,Yamaura, Jun-Ichi,Guo, Jiangang,Qi, Yanpeng,Toda, Yoshitake,Hosono, Hideo
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- Using high pressure to prepare polymorphs of the Ba2Co 1-xZnxS3 (0 ≤ x ≤ 1.0) compounds
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In this work, high pressure was used as a tool to induce structural transition and prepare metastable polymorphs of ternary sulfides. Structural transformations under high pressure of compounds belonging to the Ba 2Co1-xZnxS3 (0 ≤ x ≤ 1.0) series were studied using X-ray diffraction and electron microscopy. All members of the Ba2Co1-xZnxS3 series show the Ba2CoS3-type one-dimensional structure, but, after heating under pressure, the Ba2CoS3 compound (x = 0) separates into BaS and the two-dimensional BaCoS2-δ (δ ≈ 0), while Ba2Co1-xZnxS3 compounds with x ≥ 0.25 maintain their one-dimensional features but rearrange into polymorphs showing the Ba2MnS3-type structure. All structural transformations can be linked to shortening in interchain metal-metal distances caused by the high pressure, and the role of the zinc in preventing loss of one-dimensionality is discussed.
- Mezzadri, Francesco,Gilioli, Edmondo,Calestani, Gianluca,Migliori, Andrea,Harrison, Mark R.,Headspith, David A.,Francesconi, M. Grazia
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- Phase equilibria in the BaS-Cu2S-Gd2S3 system
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Phase equilibria in the BaS-Cu2S-Gd2S3 system have been studied along the 800 K isothermal section and the CuGdS 2-BaS, Cu2S-BaGdCuS3, BaGdCuS 3-Gd2S3, and BaGdCuS3-BaGd 2S4 polythermal sections. Complex sulfide BaGdCuS 3 is formed in the title system; it has an orthorhombic KZrCuSe 3-type structure (space group Cmcm) with the unit cell parameters equal to a = 0.40529(2) nm, b = 1.34831(6) nm, c = 1.02940(5) nm. This sulfide melts congruently at 1685 K. BaGdCuS3 is in equilibrium with sulfides Cu2S, BaS, Gd2S3, CuGdS2, BaGd 2S4, BaCu4S3, and BaCu 2S2 and with compositions in the C0 solid-solution region of the Cu2S-Gd2S3 system. Eutectics are formed between compounds CuGdS2 and BaGdCuS 3 at 7.0 mol % BaS and T = 1325 K, between BaGdCuS3 and BaS at 64.0 mol % BaS and T = 1625 K, between Cu2S and BaGdCuS 3 at 8.0 mol % BaGdCuS3 and T = 1125 K, between Gd 2S3 and BaGdCuS3 at 64.0 mol % Gd 2S3 and 1495 K, and between BaGdCuS3 and BaGd2S4 at 35 mol % BaGd2S4 and T = 1660 K.
- Sikerina,Solov'Eva,Toroshchin,Andreev
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- A simple route to complex materials: The synthesis of alkaline earth-transition metal sulfides
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A simple, low-temperature synthesis of a family of alkaline earth metal chalcogenide thin films is reported. These materials have previously only been produced from demanding, high temperature, high pressure reactions. The decomposition of calcium, barium and copper xanthates leads to the clean formation of CaS, BaS, CaCu2S2, β-BaCu2S2 and β-BaCu4S3.
- Al-Shakban, Mundher,Matthews, Peter D.,O'Brien, Paul
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- AHgSnQ4 (A = Sr, Ba; Q = S, Se): A Series of Hg-Based Infrared Nonlinear-Optical Materials with Strong Second-Harmonic-Generation Response and Good Phase Matchability
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Four Hg-based IR nonlinear-optical materials, AHgSnQ4 (A = Sr, Ba; Q = S, Se), were discovered and investigated systematically. Their structures are built of two-dimensional [HgSnQ4]2- layers, which are assembled alternately by distorted (HgQ4 and SnQ4) tetrahedra and separated by eight-coordinated A2+ cations. The two sulfides AHgSnS4 (A = Ba, Sr) exhibit large second-harmonic-generation (SHG) responses (2.8 and 1.9 × AgGaS2 at 2.09 μm), as well as large band gaps (2.77 and 2.72 eV). The two selenides AHgSnSe4 (A = Ba, Sr) show even stronger SHG responses, about 5 times that of AgGaS2. Furthermore, all four compounds show phase-matching behavior, and the results of first-principles calculation elucidate the key role of the HgQ4 group in the enhanced SHG effect in β-BaHgSnS4 and BaHgSnSe4.
- Guo, Yangwu,Liang, Fei,Li, Zhuang,Xing, Wenhao,Lin, Zhe-Shuai,Yao, Jiyong,Mar, Arthur,Wu, Yicheng
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- Role of extrusion process on kinetic of carbothermal reduction of barite
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In present study, the effect of extrusion process on kinetic of carbothermal reduction of barite was investigated. In order to improve the gasification rate potassium carbonate was doped on coke as catalyst. The mixture of barite and coke powder was shaped by a laboratory extruder and the reduction process was isothermally carried out at four temperatures, ranging 850-1000 °C. The effect of extrusion process on conversion of barite was evaluated by iodometry method. Also, a modified kinetic model was used to analyze the conversion data. The experimental results revealed that the extrusion process can effectively promote the rate constant both in catalytic and non-catalytic runs. It was proved that the rate of reaction is controlled by active site density in the presence of potassium carbonate and the extrusion process reduces activation energy approximately, 20 kJ/mol. Finally the reduction time was optimized to achieve the maximum conversion in the absence and presence of catalyst.
- Jamshidi,Salem
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- Reduction of recycled barium -ulfate
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Barium sulfate, which is recycled according to a new flowsheet of sodium sulfide production, was reduced by various carbon-containing materials (oil and furnace coke and Zh-grade coal). The reduction process was studied in comparison with the reduction of natural barite concentrate.
- Malysh,Gaisin,Volkova,Prokhorov,Tkachev
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- Synthesis, Structure, and Properties of Layered Sulfide BaCo1-xCuxS2-y
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The Cu-doped layered cobalt sulfides, BaCo1-xCuxS2-x/2and BaCo1-xCuxS2, have been synthesized with the single-phase region 0≤x≤0.5. Both series are semiconducting. The resistivity of BaCo1-xCuxS2decreases drastically with increasing Cu content. Increasing sulfur content has a similar effect in BaCo1-xCuxS2-x/2+ywith the fixed Cu concentration. In contrast, the resistivity of BaCo1-xCuxS2-x/2shows much less variation for different doping levels. Evolution from an antiferromagnetic to spin-glass state was observed for both series.
- Zhu,Ting,Feng,Hor
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- Photocatalytic, structural and optical properties of mixed anion solid solutions Ba3Sc2?xInxO5Cu2S2and Ba3In2O5Cu2S2?ySey
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Nine members of two contiguous solid solutions, Ba3Sc2?xInxO5Cu2S2and Ba3In2O5Cu2S2?ySey(x,y= 0, 0.5, 1, 1.5 and 2), were synthesised at temperatures between 800 °C and 900 °C by stoichiometric combination of binary precursors. Their structures were determined by Rietveld refinement of X-ray powder diffraction data and found to adopt the SmNi3Ge3structure withI4/mmmsymmetry. Approximate Vegard law relationships were found within each solution between the lattice parameters and composition, with an observed cell volume of 466.4 ?3for Ba3Sc2O5Cu2S2increasing to 481.0 ?3for Ba3In2O5Cu2S2and finally to 499.0 ?3for Ba3In2O5Cu2Se2. In the first solid solution, this volume increase is driven by the replacement of scandium by the larger indium ion, generating increased strain in the copper chalcogenide layer. In the second solution the substitution into the structure of the larger selenium drives further volume expansion, while relieving the strain in the copper chalcogenide layer. Band gaps were estimated from reflectance spectroscopy and these were determined to be 3.3 eV, 1.8 eV, and 1.3 eV for the three end members Ba3Sc2O5Cu2S2, Ba3In2O5Cu2S2, and Ba3Sc2In2O5Cu2Se2, respectively. For the intermediate compositions a linear relationship between band gap size and composition was observed, driven in the first solution by the introduction of the more electronegative indium lowering the conduction band minimum and in the second solution by the substitution of the electropositive selenium raising the valance band maximum. Photocatalytic activity was observed in all samples under solar simulated light, based on a dye degradation test, with the exception of Ba3In2O5Cu2Se1.5S0.5. The most active sample was found to be Ba3Sc2O5Cu2S2, the material with the largest band gap.
- Hyett, Geoffrey,Iborra-Torres, Antonio,Limburn, Gregory J.,Scanlon, David O.,Stephens, Matthew J. P.,Williamson, Benjamin A. D.
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- Crystal structures and magnetic properties of new quaternary sulfides BaLn2MS5 (Ln=La, Ce, Pr, Nd; M=Co, Zn) and BaNd2MnS5
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Crystal structures and magnetic properties are investigated for new quaternary sulfides BaLn2TS5 (Ln=La, Ce, Pr, Nd; T=Co, Zn) and BaNd2MnS5. These compounds crystallize in a tetragonal structure (space group I4mcm), which is isostructural with BaLa2MnS5. Their lattice parameters increase monotonically with the sizes of the lanthanide and transition metal. The increase of the a values is mainly due to the lanthanide size, and that of the c values is due to the transition metal size. In BaLn2CoS5, the Co2+ ions have the unquenched orbital moments. In BaNd2MnS5, the magnetic anomaly due to the antiferromagnetic ordering of the Mn2+ ion, is found at 63 K. Antiferromagnetic orderings for the Co2+ ions are observed at ca. 65 K in BaLn2CoS5 (Ln=La, Ce, Pr, Nd). For BaNd2TS5 (T=Mn, Co, Zn), the Nd3+ ions also show antiferromagnetic behavior below 6 K.
- Wakeshima, Makoto,Hinatsu, Yukio
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- Synthesis and the luminescent properties of Ba2ZnS 3:Ce,Ag phosphors
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Ba2ZnS3:Ce,Ag phosphors, emitting bluish to yellowish-green light, were synthesized by a double-crucible method. X-ray diffraction results indicate that the raw materials were completely sulfurized at 1000°C for 2 h, and all samples had a orthorhombic crystal structure with doping 0.1-1 mol % Ce3+ and codoping 0-0.2 mol % Ag+. The emission spectra resulted from (i) host-activator transition and (ii) 2D(5d)-7F5/2(4f) and 2D(5d)- 7F7/2(4f)Ce3+ transitions. The photoluminescence spectra show that the emission peaks in the 494-508 nm range (excited at λexc = 420 nm) and in the 493-537 nm range (excited around λexc = 356 nm), like the CIE color coordinate, depend on the doping concentration of the Ce3+ and Ag+ ions.
- Lin, Yu-Feng,Chang, Yen-Hwei,Tsai, Bin-Siang
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- Magnetic studies on quaternary iron sulfides BaLn2FeS 5 (Ln = Ce, Pr, Nd, Sm) by magnetic susceptibility, specific heat, 57Fe Moessbauer spectrum, and neutron diffraction measurements
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Magnetic properties of quaternary iron sulfides, BaLn2FeS 5 (Ln = Ce, Pr, Nd, Sm), have been investigated through magnetic susceptibility, electrical resistivity, specific heat, 57Fe Moessbauer spectrum, and powder neutron diffraction measurements. In these compounds, the Fe2+ ion exhibits an antiferromagnetic ordering at around 40 K. In the Nd and Sm compounds, these lanthanide ions show an antiferromagnetic ordering at 6.5 K for Ln = Nd and at 28 K for Ln = Sm. The reduction of the Fe2+ magnetic moment is observed below 120-170 K for all the compounds. Their electrical conductivities show an Arrhenius temperature-dependence, and the activation energies change at around the moment-reduction temperatures. The 57Fe Moessbauer spectra for BaPr2FeS5 indicate that the FeS4 tetrahedron is distorted prominently below the temperature at which both the magnetic susceptibility and the electrical resistivity show an anomaly in their temperature dependence. The neutron diffraction data collected for BaPr 2FeS5 at 10 K show that it has a collinear antiferromagnetic structure and that the magnetic moments of the Fe 2+ ions are parallel to the c-axis.
- Wakeshima, Makoto,Ino, Kentaro,Hinatsu, Yukio,Ishii, Yoshinobu
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- Crystal growth and characterization of a new quaternary hexagonal nonlinear crystal for the mid-IR: Ba2Ga8GeS16
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The non-centrosymmetric hexagonal Ba2Ga8GeS16 (B2GGS) crystal is grown for the first time with good optical quality by the vertical Bridgman-Stockbarger technique. The linear (transmission, dispersion, and birefringence) and nonlinear (second order susceptibility) properties of this new uniaxial nonlinear crystal for the mid-IR part of the spectrum are studied.
- Badikov, Valeriy V.,Badikov, Dmitrii V.,Shevyrdyaeva, Galina S.,Kato, Kiyoshi,Umemura, Nobuhiro,Miyata, Kentaro,Panyutin, Vladimir L.,Petrov, Valentin
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- Material Design of Green-Light-Emitting Semiconductors: Perovskite-Type Sulfide SrHfS3
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A current issue facing light-emitting devices is a missing suitable material for green emission. To overcome this, we explore semiconductors possessing (i) a deep conduction band minimum (CBM) and a shallow valence band maximum (VBM), (ii) good controllability of electronic conductivity and carrier polarity, and (iii) a directly allowed band gap corresponding to green emission. We focus on early transition metal (eTM)-based perovskites. The eTM cation's high and stable valence state makes its carrier controllability easy, and the eTM's nonbonding d orbital and the anion's p orbital, which constitute the deep CBM and shallow VBM, are favorable to n- and p-type doping, respectively. To obtain a direct band gap, we applied a scheme that folds the bands constituting the VBM at the zone boundary to the zone center where the CBM appears. Orthorhombic SrHfS3 was chosen as the candidate. The electrical conductivity was tuned from 6 × 10-7 to 7 × 10-1 S·cm-1 with lanthanum (La) doping and to 2 × 10-4 S·cm-1 with phosphorus (P) doping. Simultaneously, the major carrier polarity was controlled to n type by La doping and to p type by P doping. Both the undoped and doped SrHfS3 exhibited intense green photoluminescence (PL) at 2.37 eV. From the PL blue shift and short lifetime, we attributed the emission to a band-to-band transition and/or exciton. These results demonstrate that SrHfS3 is a promising green-light-emitting semiconductor.
- Hanzawa, Kota,Iimura, Soshi,Hiramatsu, Hidenori,Hosono, Hideo
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p. 5343 - 5349
(2019/03/29)
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- Design and synthesis of a nonlinear optical material BaAl4S7 with a wide band gap inspired from SrB4O7
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The most convenient method to generate mid-infrared (mid-IR) high-power lasers is through nonlinear optical (NLO) process using NLO materials with high laser damage threshold (LDT). The LDT is intrinsically dependent on the energy band gap, but often inverse of the NLO effect. Therefore, achieving a good balance between band gap (Eg > 3.0 eV) and NLO response (dij > 10 × KDP) in a good mid-IR NLO material is necessary. In this study, inspired by the oxide SrB4O7 with the highest LDT among all known borate crystals, we propose that the chalcogenide BaAl4S7 with similar crystal structure may have attractive NLO properties. The experiments revealed that BaAl4S7 possesses the broadest band gap (>3.95 eV) among all known mid-IR NLO chalcogenides, and its LDT is above 10 times that of the commercial material AgGaS2. Moreover, its NLO coefficient is above 10 × KDP (half of that of AgGaS2). All these features demonstrate that BaAl4S7 is a potential candidate as a good mid-IR NLO material.
- Mei, Dajiang,Jiang, Jianqiao,Liang, Fei,Zhang, Shiyan,Wu, Yuandong,Sun, Congting,Xue, Dongfeng,Lin, Zheshuai
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p. 2684 - 2689
(2018/03/23)
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- BaAu2S2: A Au-Based Intrinsic Photocatalyst for High-Performance Visible-Light Photocatalysis
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A new Au-based sulfide BaAu2S2 was obtained through solid-state reaction. It crystallizes in the tetragonal space group I41/amd with unit cell parameters of a = 6.389 72(2) ?, b = 6.389 72(2) ?, c = 12.7872(1) ?, and Z = 4. Its structure features [AuS2/2]∞ zigzag chains composed of corner-sharing AuS2 linear units. With a direct band gap of 2.49 eV, BaAu2S2 is suitable for the visible-light harvesting. Moreover, it exhibits excellent visible-light photocatalytic activity, which is 1.3 times that of graphitic carbon nitride (g-C3N4) and also demonstrates excellent circulating stability. On the basis of the crystal and electronic structure analysis, the electrons are highly delocalized along the [AuS2/2] chains, and the electron effective mass of BaAu2S2 is only approximately one-fifth of that of g-C3N4, which may help the separation of the electron/hole pairs during the photocatalytic process. Additionally, the absorption coefficient of BaAu2S2 is extremely high, exceeding 1 × 104 cm-1 over the entire absorbable visible spectrum (hν > Eg), which is significantly higher than that of g-C3N4. Such factors may contribute to its outstanding photocatalytic performances. According to our best knowledge, BaAu2S2 is the first noble metal-based chalcogenide photocatalyst reported as intrinsic light-harvesting and electron/hole-generating centers. This study may provide valuable insights for further research on photocatalytic materials.
- Zhou, Molin,Jiang, Xin,Jiang, Xingxing,Xiao, Ke,Guo, Yangwu,Huang, Hongwei,Lin, Zheshuai,Yao, Jiyong,Tung, Chen-Ho,Wu, Li-Zhu,Wu, Yicheng
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p. 5173 - 5181
(2017/05/08)
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- Preparation method of bismuth subgallate
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The invention provides a preparation method of bismuth subgallate, comprising the following steps: Step (1), adding bismuth trioxide into concentrated nitric acid to dissolve bismuth trioxide, and then adding deionized water to obtain a bismuth nitrate solution; Step (2) adding deionized water into gallic acid to dissolve gallic acid so as to obtain a gallic acid aqueous solution; Step (3), adding the gallic acid aqueous solution into the bismuth nitrate solution at the molar ratio of gallic acid in the gallic acid aqueous solution to bismuth nitrate in the bismuth nitrate solution being 1.1:1-1.2:1, so as to obtain a yellow precipitate; and Step (4) filtering the yellow precipitate to obtain a filter cake, washing the filter cake with deionized water and finally drying so as to obtain bismuth subgallate. The preparation method of bismuth subgallate is simple to operate and is cost-saving.
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Paragraph 0031
(2017/05/27)
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- Ba2GeS4 and Mg2SnS4: Synthesis, structures, optical properties and electronic structures
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Two ternary metal chalcogenides, Ba2GeS4 and Mg2SnS4, have been synthesized by a high-temperature solid-state reaction. Single-crystal X-ray diffraction analysis reveals that they crystallize in the same space group Pnma with a three-dimensional framework composed of discrete MS4 (M = Ge and Sn) tetrahedra, but they are not isostructural. The arrangements of isolated MS4 (M = Ge and Sn) units are obviously different in the Ba2GeS4 and Mg2SnS4 structures - they have their a and c axes interchanged - and this leads to different structures for the title compounds. The UV-Vis-IR diffuse reflectance spectra show that the optical band gap is about 2.05 eV for Mg2SnS4. IR spectra of the title compounds are also measured and show a wide IR transmission range. First-principle theoretical studies are used to aid the understanding of the electronic structures and linear optical properties.
- Wu, Kui,Pan, Shilie,Yang, Zhihua
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p. 33646 - 33652
(2015/04/27)
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- Syntheses and Crystal Structures of BaAgTbS3, BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and CsAgUTe3
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Five new quaternary chalcogenides of the 1113 family, namely BaAgTbS3, BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and CsAgUTe3, were synthesized by the reactions of the elements at 1173-1273 K. For CsAgUTe3 CsCl flux was used. Their crystal structures were determined by single-crystal X-ray diffraction studies. The sulfide BaAgTbS3 crystallizes in the BaAgErS3 structure type in the monoclinic space group C3,2h-C2/m, whereas the tellurides BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and CsAgUTe3 crystallize in the KCuZrS3 structure type in the orthorhombic space group D1,27,h-Cmcm. The BaAgTbS3 structure consists of edge-sharing [TbS69-] octahedra and [AgS59-] trigonal pyramids. The connectivity of these polyhedra creates channels that are occupied by Ba atoms. The telluride structure features 2∞[MLnTe32-] layers for BaCuGdTe3, BaCuTbTe3, BaAgTbTe3, and 2∞[AgUTe31-] layers for CsAgUTe3. These layers comprise [MTe4] tetrahedra and [LnTe6] or [UTe6] octahedra. Ba or Cs atoms separate these layers. As there are no short Q?Q (Q = S or Te) interactions these compounds achieve charge balance as Ba2+M+Ln3+(Q2-)3 (Q = S and Te) and Cs+Ag+U4+(Te2-)3.
- Prakash, Jai,Mesbah, Adel,Beard, Jessica C.,Ibers, James A.
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p. 1253 - 1257
(2015/06/30)
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- Syntheses, Characterization, and Optical Properties of Centrosymmetric Ba3(BS3)1.5(MS3)0.5 and Noncentrosymmetric Ba3(BQ3)(SbQ3)
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The most advanced UV-vis and IR NLO materials are usually borates and chalcogenides, respectively. But thioborates, especially thio-borometalates, are extremely rare. Here, four new such compounds are discovered by solid state reactions representing 0D structures constructed by isolated BQ3 trigonal planes and discrete MQ3 pyramids with Ba2+ cations filling among them, centrosymmetric monoclinic P21/c Ba3(BS3)1.5(MS3)0.5 (M = Sb, Bi) 1, 2 with a = 12.9255(9), 12.946(2) ?; b = 21.139(2), 21.170(2)?; c = 8.4194(6), 8.4207(8) ?; β = 101.739(5), 101.688(7)°; V = 2252.3(3), 2259.9(3) ?3 and noncentrosymmetric hexagonal P62m Ba3(BQ3)(SbQ3) (Q = S, Se) 3, 4 with a = b = 17.0560(9), 17.720(4) ?; c = 10.9040(9), 11.251(3) ?; V = 2747.1(3), 3060(2) ?3. 3 exhibits the strongest SHG among thioborates that is about three times that of the benchmark AgGaS2 at 2.05 μm. 1 and 3 also show an interesting structure relationship correlated to the size mismatching of the anionic building units that can be controlled by the experimental loading ratio of B:Sb. Syntheses, structure characterizations, and electronic structures based on the density functional theory calculations are reported. (Figure Presented).
- Li, Yan-Yan,Li, Bing-Xuan,Zhang, Ge,Zhou, Liu-Jiang,Lin, Hua,Shen, Jin-Ni,Zhang, Cheng-Yi,Chen, Ling,Wu, Li-Ming
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p. 4761 - 4767
(2015/05/27)
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- Syntheses, crystal structures, transport properties, and theoretical studies of five members of the MAn2Q5 Family: SrU2S5, BaU2Se5, PbU2S5, BaTh2S5, and BaU2Te5
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Five compounds of the MAn2Q5 family, namely, SrU2S5, BaU2Se5, PbU2S5, BaTh2S5, and BaU2Te5, have been synthesized by higherature solid-state reactions. The crystal structures of these compounds were determined by single-crystal X-ray diffraction studies. SrU2S5, BaU2Se5, PbU2S5, and BaTh2S5 crystallize in the PbU2Se5 structure type in space group C2h5-P21/c of the monoclinic system, whereas BaU2Te5 adopts the (NH4)Pb2Br5 structure type in space group D4h18-I4/mcm of the tetragonal system. There are no Q-Q bonds in these structures, so the formulas charge balance as M2+(An4+)2(Q2-)5. The An atoms in the monoclinic structure are seven- or eight-coordinated by Q atoms; the U atoms in the tetragonal structure are eight-coordinated. The M atoms in the monoclinic structure are coordinated to either eight or nine Q atoms, depending on the monoclinic angle; the M atoms in the tetragonal structure are 10-coordinated. Resistivity studies on single crystals of SrU2S5, BaU2Se5, and PbU2S5 show metallic behavior with resistivities of 0.24, 10, and 3.3 m·cm, respectively, at 298 K. Spin-polarized density functional theory in the generalized gradient approximation applied to the four U compounds suggests that they are ferromagnetic. In each compound, the density of states of one spin channel is found to be finite at the Fermi level, whereas there is a gap in the density of states of the other spin channel; this is characteristic of a half-metal.
- Prakash, Jai,Tarasenko, Mariya S.,Mesbah, Adel,Lebgue, Sbastien,Malliakas, Christos D.,Ibers, James A.
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p. 11626 - 11632
(2015/01/08)
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- Five new chalcohalides, Ba3GaS4X (X = Cl, Br), Ba3MSe4Cl (M = Ga, In), and Ba7In 2Se6F8: Syntheses, crystal structures, and optical properties
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Five new chalcohalides, Ba3GaS4X (X = Cl, Br), Ba3MSe4Cl (M = Ga, In), and Ba7In 2Se6F8, have been synthesized by conventional high-temperature solid-state method. The
- Feng, Kai,Yin, Wenlong,Lin, Zuohong,Yao, Jiyong,Wu, Yicheng
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p. 11503 - 11508
(2013/10/22)
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- High-Spin cobalt(II) ions in square planar coordination: Structures and magnetism of the oxysulfides Sr2CoO2Cu2S 2 and Ba2CoO2Cu2S2 and their solid solution
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The antiferromagnetic structures of the layered oxychalcogenides (Sr 1-xBax)2CoO2Cu2S 2 (0 ≥ x ≥ 1) have been determined by powder neutron diffraction. In these compounds Co2+ is
- Smura, Catherine F.,Parker, Dinah R.,Zbiri, Mohamed,Johnson, Mark R.,Gal, Zoltan A.,Clarke, Simon J.
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p. 2691 - 2705
(2011/04/23)
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- The effect of particle size distribution on barite reduction
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The present study is a follow-up of investigation on barite reduction to barium sulfide as a function of starting particle size distribution and temperature of reaction. In this work we study the high temperature reduction process of barite from the view
- Salem,Osgouei, Y. Tavakkoli
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p. 1489 - 1493
(2009/07/10)
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- M(SCN)2 (M = Eu, Sr, Ba): Crystal structure, thermal behaviour, vibrational spectroscopy
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Single crystals of M(SCN)2 (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl2 (M = Eu, Sr, Ba) at 340°C. The isotypic crystal structures of the thiocyanates M(SCN)2 (C2/c, Z = 4, Eu: a = 979.3(2), b = 660.8(1), c = 815.7(2) pm, β = 91.58(3)°, Rall = 0.0245, Sr: a = 985.5(2), b = 662.9(2), c = 819.6(2) pm, β = 91.29(3)°, Rall = 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, β = 92.43(2)°, Rall = 0.0392) contain alternating layers of M2+ and SCN-. According to M(SCN)4/4(NCS)4/4 M2+ is eight-coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed. WILEY-VCH Verlag GmbH, 2001.
- Wickleder, Claudia
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p. 1693 - 1698
(2008/10/08)
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- Investigation on thermal decomposition of FeS2 and BaO2 mixtures. Part II
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The thermal decomposition of FeS2 and BaO2 mixtures (mol ratio from 2 to 8) was studied in oxygen containing gas medium using dynamic heating rate. The solid decomposition products have been investigated with X-ray power diffraction and Moessbauer spectrometer. The thermal process has two main stages. In the presence of BaO2 the mixtures have a lower initial temperature of iron sulfide burning. The same time by the increasing of BaO2 content in the mixtures the diffusion difficulties are withdrawn in higher temperature ranges. It is proved that as intermediates BaSO4, nonstoichiometric sulfide, barium ferrites and Fe2O3 are formed. The content of many solid phases in the final product is in relationship with the initial ratio of BaO2 and FeS2.
- Pelovski,Petkova
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p. 101 - 108
(2008/10/08)
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- Diagrams of the BaS-Ln2S3 (Ln = Sm, Gd) Systems
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The BaS-Sm2S3 and BaS-Gd2S3 systems are studied by physicochemical methods. They are found to have similar phase diagrams. BaSm2S4 and BaGd2S4, orthorhombic compounds, with a = 1.224 nm, b = 1.443 nm, c = 0. 412 nm for BaSm2S4 and a = 1.221 nm, b = 1.462 nm, c = 0.410 nm for BaGd2S4, melting congruently at 1990 and 2000 K, respectively, exist in these systems. The BaSm2S4-based solid solution extends at 1720 K from 50 to 56 mol % Sm2S3. The eutectic between BaS and BaSm2S4 lies at 35 mol % Sm2S3, 1900 K; that between BaSm2S4 and Sm2S3, at 65 mol % Sm2S3, 1890 K; at 33 mol % Gd2S3, 1890 K lies between BaS and BaGd2S4; and at 73 mol % Gd2S3, 1825 K is between BaGd2S4 and Gd2S3. The solubilities are 2 mol % Sm2S3 in BaS at 1820 K; 15 and 7 mol % BaS in γ-Sm2S3 at 1820 and 1470 K, respectively; 2 mol % Gd2S3 in BaS at 1800 K; and 4 mol % BaS in γ-Gd2S3 at 1800 K. With increasing BaS content from zero to the solubility limits, the α ? γ transition temperatures decrease for the Sm2S3- and Gd2S3-based solid solutions from 1445 to 1400 K and from 1475 to 1465 K, respectively.
- Andreev,Parshukov,Bamburov
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p. 775 - 778
(2008/10/08)
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- Enthalpies of formation of BaPdS2 and LaPd3S4
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The BaPdS2 mixed palladium sulfide has been synthesized by direct reaction of a stoichiometric mixture of the PdS and BaS binary constituent sulfides. The standard molar enthalpies of formation of BaPdS2 and LaPd3S4 mixed sulfides were determined by the method of direct reaction calorimetry through synthesizing the respective compounds in a calorimetric cell from the stoichiometric mixture of appropriate starting materials. Combining the experimental results with the reference data for the starting materials, we found Δf,298H0m(BaPdS 2)=-515.4±16.8 kJ mol-1; and Δf,298H0m(LaPd3S 4)=-817.6±43.8 kJ mol-1.
- Zubkov,Fujino,Waseda,Sato,Yamada
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- Mechanism and kinetics of inorganic sulphates decomposition
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Thermal decomposition of different inorganic sulphates are presented. A number of techniques, but mainly TG and DTA, are used to prove the mechanism and kinetics of CaSO4, BaSO4, FeSO4·xH 2O, Al2(SO4)3·xH2O under various gas atmospheres. It is shown how the partial pressure of gas components and heating rate may effect the mechanism and kinetic parameters. There are also examples on the effects of some additives and initial treatment on the thermal processes. On the base of the results obtained some recommendations are given concerning the precautions to be taken into account in the thermal decomposition studies and the sulphur recovering.
- Pelovski,Petkova
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p. 1227 - 1241
(2008/10/08)
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- Synthesis and properties of BaCuxNi1-xS2-δ (0.0 < x < 0.4; 0.0 < δ < 0.09)
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BaCuxNi1-xS2-δ is found to be single phase for x = 0, 0.1, 0.2, 0.3 and 0.4, and δ = 0.00 to 0.09 and is isostructural with tetragonal BaNiS2. Lattice parameters (a = 4.4374(2) angstrom and c = 8.9089(4) angstrom for x = 0.0; a = 4.4659(2) angstrom and c = 8.9549(5) angstrom for x = 0.4) were determined using X-ray powder diffraction. For x > 0 the resistivity is only weakly temperature dependent and ρ(300) ' 10-3 Ω cm. Magnetic susceptibility data indicate Pauli paramagnetic behavior with χ0 = 0.8 × 10-6 emu g-1.
- Brock, Stephanie L.,Kauzlarich, Susan M.
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- Chemistry and thermodynamics of solid and vapor phases in the barium-sulfide, gallium-sulfide system
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The technologically important BaS-Ga2S3 solid system was studied and interpreted with a generalized acid-base theory counting BaS(s) as a strong base and Ga2S3(s) as an acid. The strongest bonding in any MS-Ga2S3 system was found. Vaporization of solid samples whose initial composition was BaGa2S4(s) was studied in the temperature range 1234-1361 K by the simultaneous Knudsen-effusion and Volmer-effusion methods. The sample vaporized incongruently and the composition of the solid changed successively to yield a number of phases The vaporization reactions and the average third-law ΔvH°(298 K) in kJ are presented, as well as the enthalpies of ternary phases with respect to those of the binary constituents BaS(s) and Ga2S3(s) in kJ per mole of Ga2S3.
- Mukdeeprom-Burckel,Edwards
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p. 163 - 172
(2008/10/08)
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- Optical properties of alkaline-earth chalcogenides. I. Single crystal growth and infrared reflection spectra due to optical phonons
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Single crystals of alkaline-earth chalcogenides, CaS, CaSe, SrS, SrSe, BaS and BaSe, have been prepared by the floating-zone method using a Xe-arc image furnace. Details of the crystal growth technique are described. As the first report of our studies on the optical properties of these IIa-VIb compounds, the infrared reflection spectra due to the optical phonons are presented. From a dispersion analysis of the spectra, the frequencies of transverse and longitudinal optical phonons and related dispersion parameters are determined. Discussions are made on the effective charges and the chemical trend of these binary compounds.
- Kaneko, Yoshio,Morimoto, Koichi,Koda, Takao
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p. 2247 - 2254
(2008/10/08)
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