Xn:Harmful;21109-95-5Relevant articles and documents
Crystal structure and physical properties of Ba2Nb3S8I: A new misfit-layered transition-metal dichalcogenide superconductor
Baker, Mitchell T.,Benjamin, S. M.,Lin, Qisheng,Neumeier, J. J.,Smith, M. G.
, (2021)
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.
Thermal reduction of barium sulphate with carbon monoxide-A thermogravimetric study
Hlabela,Neomagus,Waanders,Bruinsma
, p. 67 - 70 (2010)
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.
Synthesis, Structure, and Optical Properties of Antiperovskite-Derived Ba2MQ3X (M = As, Sb; Q = S, Se; X = Cl, Br, I) Chalcohalides
Wang, Ruiqi,Zhang, Xian,He, Jianqiao,Bu, Kejun,Zheng, Chong,Lin, Jianhua,Huang, Fuqiang
, p. 1449 - 1454 (2018)
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.
OPTICAL PROPERTIES OF ALKALINE-EARTH CHALCOGENIDES. II. VACUUM ULTRAVIOLET REFLECTION SPECTRA IN THE SYNCHROTRON RADIATION REGION OF 4-40 ev.
Kaneko,Morimoto,Koda
, p. 4385 - 4396 (1983)
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.
Synthesis and characterization of two lead-containing metal chalcogenides: Ba5Pb2Sn3S13 and Ba6PbSn3Se13
Abudurusuli, Ailijiang,Ding, Hanqin,Wu, Kui
, p. 133 - 138 (2017)
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
Layered compounds BaM2Ge4Ch6 (M = Rh, Ir and Ch = S, Se) with pyrite-type building blocks and Ge-Ch heteromolecule-like anions
Lei, Hechang,Yamaura, Jun-Ichi,Guo, Jiangang,Qi, Yanpeng,Toda, Yoshitake,Hosono, Hideo
, p. 5684 - 5691 (2014)
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
Phase equilibria in the BaS-Cu2S-Gd2S3 system
Sikerina,Solov'Eva,Toroshchin,Andreev
, p. 1982 - 1986 (2007)
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.
A simple route to complex materials: The synthesis of alkaline earth-transition metal sulfides
Al-Shakban, Mundher,Matthews, Peter D.,O'Brien, Paul
, p. 10058 - 10061 (2017)
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.
Role of extrusion process on kinetic of carbothermal reduction of barite
Jamshidi,Salem
, p. 108 - 114 (2010)
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.
Synthesis, Structure, and Properties of Layered Sulfide BaCo1-xCuxS2-y
Zhu,Ting,Feng,Hor
, p. 111 - 113 (1998)
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.
Crystal structures and magnetic properties of new quaternary sulfides BaLn2MS5 (Ln=La, Ce, Pr, Nd; M=Co, Zn) and BaNd2MnS5
Wakeshima, Makoto,Hinatsu, Yukio
, p. 163 - 169 (2001)
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.
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
Wakeshima, Makoto,Ino, Kentaro,Hinatsu, Yukio,Ishii, Yoshinobu
, p. 1519 - 1525 (2003)
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.
Material Design of Green-Light-Emitting Semiconductors: Perovskite-Type Sulfide SrHfS3
Hanzawa, Kota,Iimura, Soshi,Hiramatsu, Hidenori,Hosono, Hideo
, p. 5343 - 5349 (2019/03/29)
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.
