共查询到20条相似文献,搜索用时 6 毫秒
1.
Daniel E. Bugaris 《Journal of solid state chemistry》2009,182(5):1017-6666
The compound Cs2Hg2USe5 was obtained from the solid-state reaction of U, HgSe, Cs2Se3, Se, and CsI at 1123 K. This material crystallizes in a new structure type in space group P2/n of the monoclinic system with a cell of dimensions a=10.276(6) Å, b=4.299(2) Å, c=15.432(9) Å, β=101.857(6) Å, and V=667.2(6) Å3. The structure contains layers separated by Cs atoms. Within the layers are distorted HgSe4 tetrahedra and regular USe6 octahedra. In the temperature range of 25-300 K Cs2Hg2USe5 displays Curie-Weiss paramagnetism with μeff=3.71(2) μB. The compound exhibits semiconducting behavior in the [010] direction; the conductivity at 298 K is 3×10−3 S/cm. Formal oxidation states of Cs/Hg/U/Se may be assigned as +1/+2/+4/− 2, respectively. 相似文献
2.
RbAuUSe3, CsAuUSe3, RbAuUTe3, and CsAuUTe3: Syntheses and structure; magnetic properties of RbAuUSe3
The compounds RbAuUSe3, CsAuUSe3, and RbAuUTe3 were synthesized at 1073 K from the reactions of U, Au, Q, and A2Q3 (A=Rb or Cs; Q=Se or Te). The compound CsAuUTe3 was synthesized at 1173 K from the reaction of U, Au, Te, and CsCl as a flux. These isostructural compounds crystallize in the KCuZrS3 structure type in space group Cmcm of the orthorhombic system. The structure consists of layers that contain nearly regular UQ6 octahedra and distorted AuQ4 tetrahedra. The infinite layers are separated by bicapped trigonal prismatic A cations. The magnetic behavior of RbAuUSe3 deviates significantly from Curie–Weiss behavior at low temperatures. For T>200 K, the values of the Curie constant C and the Weiss constant θp are 1.82(9) emu K mol−1 and −3.5(2)×102 K, respectively. The effective magnetic moment μeff is 3.81(9) μB. Formal oxidation states of A/Au/U/Q may be assigned as +1/+1/+4/−2, respectively. 相似文献
3.
The new compound MnSbS2Cl was synthesised from a mixture of MnS, MnCl2 and Sb2S3 at 500 °C. Single crystal study indicates orthorhombic symmetry, space group Pnma (No. 62), with , , , and Z=4. The refinement converged to R=0.0374 and wR=0.0716 for 742 unique reflections and 32 parameters. The crystal structure of MnSbS2Cl is isotypic with stibnite Sb2S3 and consists of waved layers of corner-sharing MnS4Cl2 octahedra along the a axis and edge-sharing octahedra along the b axis, which are separated by antimony atoms. MnSbS2Cl susceptibility shows an antiferromagnetic behaviour below 40 K with an increase at about 23 K. 相似文献
4.
Shilie Pan Jared P. Smit Evan S. Stampler Jaewook Baek Kenneth R. Poeppelmeier 《Journal of solid state chemistry》2008,181(8):2087-2091
Bi2Cu5B4O14 crystallizes in the noncentrosymmetric triclinic space group P1 (No. 1) with cell parameters a=10.1381(11) Å, b=9.3917(11) Å, c=3.4566(4) Å, α=105.570(2)°, β=92.275(2)°, γ=107.783(2)°, Z=1 and R1=0.0401 and wR2=0.0980. It is a layered structure that is built up from sheets of rectangular CuO4 and trigonal BO3 groups. The sheets are connected by infinite chains of edge shared BiO6 polyhedra that intersect the bc plane at an angle slightly greater than 90°. The second-harmonic generation efficiency of Bi2Cu5B4O14, using 1064 nm radiation, is about one half times that of KH2PO4. 相似文献
5.
D.-G. Chen D.-S. Wu H. Zhang Y.-C. Zhang Y.-J. Gong Z.-G. Kan 《Journal of solid state chemistry》2004,177(11):3927-3933
A novel compound Ba2ZnV2O8 has been synthesized in high temperature solution reaction and its crystal structure has been characterized by means of single crystal X-ray diffraction analysis. It crystallizes in monoclinic system and belongs to space group P21/c with a=7.9050(16), b=16.149(3), , β=90.49(3). It builds up from 1-D branchy chains of [ZnV2O84−]∞, and the Ba2+ cations are located in the space among these chains. The IR spectrum, ultraviolet-visible diffuse reflection integral spectrum and fluorescent spectra of this compound have been investigated. The calculated results of energy band structure by the density functional theory method show that the solid-state compound of Ba2ZnV2O8 is an insulator with direct band gap of 3.48 eV. The calculated total and partial density of states indicate that the top valence bands are contributions from the mixings of O-2p, V-3d, and Zn-3d states and low conduction bands mostly originate from unoccupied antibonding states between the V-3d and O-2p states. The V-O bonds are mostly covalence characters and Zn-O bonds are mostly ionic interactions, and the ionic interaction strength is stronger between the Ba-O than between the Zn-O. The refractive index of nx, ny, and nz is estimated to be 1.7453, 1.7469, and 1.7126, respectively, at wavelength of 1060 nm for Ba2ZnV2O8 crystal. 相似文献
6.
RbVSe2 has been synthesized at 773 K through the reaction of V and Se with a Rb2Se3 reactive flux. The compound crystallizes in the orthorhombic space group D2h24-Fddd with 16 formula units in a cell of dimensions , , and at . The structure possesses infinite one-dimensional chains of edge-sharing VSe4 tetrahedra separated from the Rb+ ions. These chains distort slightly to chains. The V-V distance within these chains is 2.8362(4) Å. First-principles total energy calculations indicate that a non-magnetic configuration for the V3+ cations is the most stable. 相似文献
7.
Mikhail Sofin 《Journal of solid state chemistry》2005,178(12):3708-3714
Na3Cu2O4 and Na8Cu5O10 were prepared via the azide/nitrate route from stoichiometric mixtures of the precursors CuO, NaN3 and NaNO3. Single crystals have been grown by subsequent annealing of the as prepared powders at 500 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structures (Na3Cu2O4: P21/n, Z=4, a=5.7046(2), b=11.0591(4), c=8.0261(3) Å, β=108.389(1)°, 2516 independent reflections, R1(all)=0.0813, wR2 (all)=0.1223; Na8Cu5O10: Cm, Z=2, a=8.228(1), b=13.929(2), , β=111.718(2)°, 2949 independent reflections, R1(all)=0.0349, wR2 (all)=0.0850), the main feature of both crystal structures are CuO2 chains built up from planar, edge-sharing CuO4 squares. From the analysis of the Cu-O bond lengths, the valence states of either +2 or +3 can be unambiguously assigned to each copper atom. In Na3Cu2O4 these ions alternate in the chains, in Na8Cu5O10 the periodically repeated part consists of five atoms according to CuII-CuII-CuIII-CuII-CuIII. The magnetic susceptibilities show the dominance of antiferromagnetic interactions. At high temperatures the compounds exhibit Curie-Weiss behaviour (Na3Cu2O4: , , Na8Cu5O10: , , magnetic moments per divalent copper ion). Antiferromagmetic ordering is observed to occur in these compounds below 13 K (Na3Cu2O4) and 24 K (Na8Cu5O10). 相似文献
8.
The crystal structure of Sr4Mn2NiO9 has been refined on single crystal. This phase belongs to the series A1+x(A′xB1–x)O3 (x=1/3) related to the 2H-hexagonal perovskite. The structure contains transition metals in chains of oxide polyhedra (trigonal prisms and octahedra); neighboring chains are separated from each other by the Sr atoms. The sequence of the face sharing polyhedra along the chains is two octahedra + one trigonal prism. Mn occupies the octahedra and Ni is disordered in the trigonal prism with ≈80% in the pseudo square faces of the prism and ≈20% at the centre. This result has been confirmed by XANES experiments at Mn K and Ni K edges, respectively. Sr4Mn2NiO9 is antiferromagnetic with a Néel temperature at T=3 K. The Curie constant measured at high temperature is in good agreement with ≈80% of the Ni2+ ions in the spin state configuration S=0. 相似文献
9.
Two new potassium uranyl molybdates K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6 have been obtained by solid state chemistry . The crystal structures were determined by single crystal X-ray diffraction data, collected with MoKα radiation and a charge coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least square method on the basis of F2 for all unique reflections, with R1=0.046 for 136 parameters and 1412 reflections with I?2σ(I) for K2(UO2)2(MoO4)O2 and R1=0.055 for 257 parameters and 2585 reflections with I?2σ(I) for K8(UO2)8(MoO5)3O6. The first compound crystallizes in the monoclinic symmetry, space group P21/c with a=8.250(1) Å, b=15.337(2) Å, c=8.351(1) Å, β=104.75(1)°, ρmes=5.22(2) g/cm3, ρcal=5.27(2) g/cm3 and Z=4. The second material adopts a tetragonal unit cell with a=b=23.488(3) Å, c=6.7857(11) Å, ρmes=5.44(3) g/cm3, ρcal=5.49(2) g/cm3, Z=4 and space group P4/n.In both structures, the uranium atoms adopt a UO7 pentagonal bipyramid environment, molybdenum atoms are in a MoO4 tetrahedral environment for K2(UO2)2(MoO4)O2 and MoO5 square pyramid coordination in K8(UO2)8(MoO5)3O6. These compounds are characterized by layered structures. The association of uranyl ions (UO7) and molybdate oxoanions MoO4 or MoO5, give infinite layers [(UO2)2(MoO4)O2]2− and [(UO2)8(MoO5)3O6]8− in K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6, respectively. Conductivity properties of alkali metal within the interlayer spaces have been measured and show an Arrhenius type evolution. 相似文献
10.
Fu Qiang Huang 《Journal of solid state chemistry》2003,174(2):334-341
Three new compounds, Cs2Bi2ZnS5, Cs2Bi2CdS5, and Cs2Bi2MnS5, have been synthesized from the respective elements and a reactive flux Cs2S3 at 973 K. The compounds are isostructural and crystallize in a new structure type in space group Pnma of the orthorhombic system with four formula units in cells of dimensions at 153 K of a=15.763(3), b=4.0965(9), c=18.197(4) Å, V=1175.0(4) Å3 for Cs2Bi2ZnS5; a=15.817(2), b=4.1782(6), c=18.473(3) Å, V=1220.8(3) Å3 for Cs2Bi2CdS5; and a=15.830(2), b=4.1515(5), c=18.372(2) Å, V=1207.4(2) Å3 for Cs2Bi2MnS5. The structure is composed of two-dimensional ∞2[Bi2MS52−] (M=Zn, Cd, Mn) layers that stack perpendicular to the [100] axis and are separated by Cs+ cations. The layers consist of edge-sharing ∞1[Bi2S66−] and ∞1[MS34−] chains built from BiS6 octahedral and MS4 tetrahedral units. Two crystallographically unique Cs atoms are coordinated to S atoms in octahedral and monocapped trigonal prismatic environments. The structure of Cs2Bi2MS5, is related to that of Na2ZrCu2S4 and those of the AMM′Q3 materials (A=alkali metal, M=rare-earth or Group 4 element, M′= Group 11 or 12 element, Q=chalcogen). First-principles theoretical calculations indicate that Cs2Bi2ZnS5 and Cs2Bi2CdS5 are semiconductors with indirect band gaps of 1.85 and 1.75 eV, respectively. The experimental band gap for Cs2Bi2CdS5 is ≈1.7 eV, as derived from its optical absorption spectrum. 相似文献
11.
Unique magnetic properties of a ternary uranate Ba2U2O7 are reported. Magnetic susceptibility measurements reveal that this compound undergoes a magnetic transition at 19 K. Below this temperature, magnetic hysteresis was observed. The results of the low-temperature specific heat measurements below 30 K support the existence of the second-order magnetic transition at 19 K. Ba2U2O7 undergoes a canted antiferromagnetic ordering at this temperature. The magnetic anomaly which sets in at 58 K may be due to the onset of one-dimensional magnetic correlations associated with the linear chains formed by U ions. The analysis of the experimental magnetic susceptibility data in the paramagnetic temperature region gives the effective magnetic moment μeff=0.73 μB, the Weiss constant θ=−10 K, and the temperature-independent paramagnetic susceptibility χTIP=0.14×10−3 emu/mole.The magnetic susceptibility results and the optical absorption spectrum were analyzed on the basis of an octahedral crystal field model. The energy levels of Ba2U2O7 and the crystal field parameters were determined. 相似文献
12.
Single crystals of the tungstates Ba2MgWO6 and Ba2ZnWO6 have been grown for the first time. The crystals were prepared with molten potassium carbonate acting as a flux. According to the single-crystal X-ray diffraction structure determination, the compounds crystallize in space group Fm3¯m of the cubic system with a double perovskite structure, A2BB′O6. These structural findings were confirmed with neutron diffraction on polycrystalline samples synthesized by a high-temperature solid-state route. Both sets of diffraction data reveal that the M2+ and W6+ cations are fully ordered on the B and B′ sites. Ba2MgWO6 and Ba2ZnWO6 exhibit room-temperature luminescence with green and yellow emissions, respectively. 相似文献
13.
Wei Liu Xin Xin Yang Hao Hong Chen Ya Xi Huang Walter Schnelle Jing Tai Zhao 《Solid State Sciences》2004,6(12):1375-1380
A nickel diphosphate with mixed cations, Na(NH4)[Ni3(P2O7)2(H2O)2] with a layered structure has been synthesized under hydrothermal conditions for the first time and characterized by single crystal X-ray diffraction, IR spectroscope and magnetization measurements. The structure consists of cis- and trans-edge sharing NiO6 octahedral chains linked via P2O7 units to [Ni3P4O16]2− layers. The ammonium and sodium cations are alternately located in the interlayer spaces. The mixed cations play an important role in the structural formation of this layered compound, leading to a new layer-stacking variant. The magnetic susceptibility obeys a Curie–Weiss law with μeff of 3.32 μB, showing the Ni2+ character and weak antiferromagnetic interactions. 相似文献
14.
Mariya Zelinska 《Journal of solid state chemistry》2011,184(3):516-11812
The new lanthanum copper telluride La3Cu5−xTe7 has been obtained by annealing the elements at 1073 K. Single-crystal X-ray diffraction studies revealed that the title compound crystallizes in a new structure type, space group Pnma (no. 62) with lattice dimensions of a=8.2326(3) Å, b=25.9466(9) Å, c=7.3402(3) Å, V=1567.9(1) Å3, Z=4 for La3Cu4.86(4)Te7. The structure of La3Cu5−xTe7 is remarkably complex. The Cu and Te atoms build up a three-dimensional covalent network. The coordination polyhedra include trigonal LaTe6 prisms, capped trigonal LaTe7 prisms, CuTe4 tetrahedra, and CuTe3 pyramids. All Cu sites exhibit deficiencies of various extents. Electrical property measurements on a sintered pellet of La3Cu4.86Te7 indicate that it is a p-type semiconductor in accordance with the electronic structure calculations. 相似文献
15.
Kang Min Ok 《Journal of solid state chemistry》2006,179(5):1345-1350
A new one-dimensional tellurite phosphate, Ba2TeO(PO4)2 has been synthesized by standard solid-state reaction techniques using BaCO3, TeO2, and (NH4)H2PO4 as reagents. The structure of Ba2TeO(PO4)2 was determined by single-crystal X-ray diffraction. Ba2TeO(PO4)2 crystallizes in the triclinic space group P-1 (No. 2), with , , , α=76.843(4)°, β=79.933(4)°, γ=75.688(4)°, , and Z=2. Ba2TeO(PO4)2 has a novel one-dimensional chain structure that is composed of PO4 tetrahedra and TeO5 polyhedra. Te4+ cations are in asymmetric coordination environments attributable to their lone pairs. The lone pairs on the Te4+ cations point in the [100] and [−100] direction and interact with the Ba2+ cations. Infrared, Raman, and UV-Vis diffuse reflectance spectroscopy, thermogravimetric analysis, and dipole moment calculations are also presented. 相似文献
16.
Carlo Bellitto Elvira M. Bauer Alain Meerschaut Guido Righini 《Journal of solid state chemistry》2006,179(2):579-589
Fe[(CH3(CH2)2PO3)(H2O)] (1) and Fe[(CH3(CH2)17PO3)(H2O)] (2) were synthesized by reaction of FeCl2·6H2O and the relevant phosphonic acid in water in presence of urea and under inert atmosphere. The compounds were characterized by elemental and thermogravimetric analyses, UV-visible and IR spectroscopy. The crystal structure of (1) was determined from X-ray single crystal diffraction studies at room temperature: monoclinic symmetry, space group P21, , , , and β=98.62(3)°. The compound is lamellar and the structure is hybrid, made of alternating inorganic and organic layers along the c direction. The inorganic layers consist of Fe(II) ions octahedrally coordinated by five phosphonate oxygen atoms and one from the water molecule, separated by bi-layers of propyl groups. A preliminary structure characterization of compound (2) suggests a similar layered structure, but with an interlayer spacing of 40.3 Å. The magnetic properties of the compounds were both studied by a dc and ac SQUID magnetometer. Fe[(CH3(CH2)2PO3)(H2O)] (1) obeys the Curie-Weiss law at temperatures above 50 K (, ), indicating a Fe +II oxidation state, a high-spin d6 (S=2) electronic configuration and an antiferromagnetic exchange couplings between the near-neighbouring Fe(II) ions. Below , Fe[(CH3(CH2)2PO3)(H2O)] exhibits a weak ferromagnetism. The critical temperature of has been determined by ac magnetic susceptibility measurements. Compound (2) shows the same paramagnetic behaviour of the iron (II) propyl derivative. The values of C and θ were found to be and −44 K, respectively, thus suggesting the presence of Fe +II ion in the S=2 spin state and antiferromagnetic interactions between Fe(II) ions at low temperatures. Zero-field and field cooled magnetic susceptibility vs. T plots do not overlap below , suggesting the presence of an ordered magnetic state. The critical temperature, TN, has been located by the peaks at from the ac susceptibility (χ′and χ″) vs. T plots. Below TN hysteresis loops recorded in the temperature region show an S-shape, while below 15 K assume an ellipsoid form. They reveal that compound (2) is a weak ferromagnet. The critical temperature TN in these layered Fe(II) alkylphosphonates is independent of the distance between the inorganic layers. 相似文献
17.
Single crystals of KBaMnO4 and KBaAsO4 were grown using the hydroflux method and characterized by single crystal X-ray diffraction. Both compounds crystallize in the orthorhombic space group Pnma with a = 7.7795(4) Å, b = 5.8263(3) Å, and c = 10.2851(5) Å for the manganate and a = 7.7773(10) Å, b = 5.8891(8) Å, and c = 10.3104(13) Å for the arsenate. The materials exhibit a three-dimensional crystal structure consisting of isolated MnO43− or AsO43− tetrahedra, with the charge balance maintained by K+ and Ba2+. Each tetrahedron is surrounded by six K+ and five Ba2+, and shares its corner/edge with KO10 polyhedra and corner/edge/face with BaO9 polyhedra, respectively. The crystal growth, crystal structure and magnetic properties are discussed. 相似文献
18.
A quaternary phase, Ba3La3Mn2W3O18, was synthesized in reduced atmosphere (5% H2/Ar) at 1200 °C and characterized by using powder X-ray diffraction, electron diffraction and high resolution TEM. Ba3La3Mn2W3O18 crystallizes in rhombohedral space group with the cell parameters, and , and can be attributed to the n=6 member in the B-site deficient perovskite family, AnBn−1O3n. The structure can be described as close-packed [La/BaO3] arrays in the sequence of (hcccch)3, wherein the B-site cations, W and Mn, occupy five octahedral layers in every six octahedral layers, which leave a vacant octahedral layers separating the 5-layer perovskite blocks. The B-cation layers in the perovskite block alternate along the c-axis in a sequence of W6+-Mn2+-W5+-Mn2+-W6+. The bond valence calculation and optical reflection spectrum confirm the presence of W5+. This compound behaves paramagnetically in wide temperature range and weak antiferromagnetic interaction only occurs at low temperatures. 相似文献
19.
Teresa Berrocal José L. Mesa Edurne S. Larrea Begoña Bazán José L. Pizarro Luis Lezama Teófilo Rojo María I. Arriortua 《Journal of solid state chemistry》2011,184(10):2623-2628
The (NH4)0.80Li0.20[Fe(AsO4)F] compound has been synthesized under mild hydrothermal conditions. The compound crystallize in the orthorhombic Pna21 space group, with cell parameters a=13.352(9), b=6.7049(9), c=10.943(2) Å and Z=8. The compound belongs to the KTiO(PO4) structure type, with chains alternating FeO4F2 octahedra and AsO4 tetrahedra, respectively, running along the “a” and “b” crystallographic axes. The diffuse reflectance spectrum in the visible region shows the forbidden electronic transitions characteristic of the Fe(III) d5-high spin cation in slightly distorted octahedral geometry. The Mössbauer spectrum at room temperature is characteristic of iron (III) cations. The ESR spectra, carried out from room temperature to 200 K, remain isotropic with variation in temperature; the g-value being 1.99(1). Magnetic measurements indicate the predominance of strong antiferromagnetic interactions. 相似文献
20.
In the presence of NBu4nBr acting as phase-transfer reagent, organosilicon trichloride C2H5SiCl3 reacts in acetonitrile with the trivacant tungstophosphate sodium salt β-A-Na8H[PW9O34]·24H2O to give hybrid organosilyl polyoxotungstate derivative α-A-[NBu4n]3[PW9O34(C2H5SiO)3(C2H5Si)]. X-ray single crystal structural analysis indicates that the title compound is monoclinic, space group Cc, with lattice constants a=26.828(5), b=22.459(5), c=17.517(4) Å, β=103.19(3)°, V=10,276(4) Å3, Z=4, R=0.0462. According to the result of X-ray single crystal diffraction and chemical analysis, the hybrid polyanion consists of one α-A-[PW9O34]9− framework on which are grafted simultaneously three RSiO groups through six Si-O-W bridge bonds, each of which is attached to the fourth RSi group through three Si-O-Si bridge bonds. The hybrid polyanion becomes a partial saturated, closed cage structure and also has an assembly of virtual C3V symmetry. 相似文献