共查询到20条相似文献,搜索用时 15 毫秒
1.
The compound Cs 2Hg 2USe 5 was obtained from the solid-state reaction of U, HgSe, Cs 2Se 3, 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) Å 3. The structure contains layers separated by Cs atoms. Within the layers are distorted HgSe 4 tetrahedra and regular USe 6 octahedra. In the temperature range of 25-300 K Cs 2Hg 2USe 5 displays Curie-Weiss paramagnetism with μeff=3.71(2) μ B. 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.
The alkaline-earth uranium chalcogenide Ba 2Cu 2US 5 was obtained in a two-step reaction from BaS, Cu 2S, and US 2. Ba 2Cu 2US 5 crystallizes in a new structure type in space group C2/ m of the monoclinic system with two formula units in a cell of dimensions a=13.606(3) Å, b=4.0825(8) Å, c=9.3217(19) Å, and β=116.32(3)° (153 K). The structure consists of layers separated by Ba atoms in bicapped trigonal-prismatic coordination. The two-dimensional layer is built from US 6 octahedra and CuS 4 tetrahedra. The connectivity of the MS n polyhedra within the layer in the [001] direction is oct tet tet oct tet tet. A μeff value of 2.69(2) μB/U was obtained from the magnetic susceptibility data. No magnetic transition was observed for Ba 2Cu 2US 5 down to 2 K. 相似文献
3.
The AnMnSe 3 ( An=Th, U) compounds were synthesized from high-temperature solid-state reactions of the constituent elements at 1223 and 1273 K, respectively. Both compounds are isostructural with UFeS 3 and crystallize in the space group Cmcm of the orthorhombic system with four formula units in a cell. Cell constants (Å) at 153 K are: ThMnSe 3, 4.0304(4), 12.795(1), 9.2883(9); UMnSe 3, 3.931(5), 12.705(14), 9.148(10). The structure comprises layers of MnSe 6 octahedra that alternate with layers of AnSe 8 bicapped trigonal prisms along the b-axis. Because there are no Se-Se bonds in the structure of AnMnSe 3 the formal oxidation states of An/Mn/Se are 4+/2+/2−. UMnSe 3 is a ferromagnet with TC=62 K. 相似文献
4.
The six LnYb Q3 compounds β-LaYbS 3, LaYbSe 3, CeYbSe 3, PrYbSe 3, NdYbSe 3, and SmYbSe 3 have been synthesized from high-temperature solid-state reactions of the constituent elements at 1223 K. The compounds are isostructural to UFeS 3 and crystallize in the space group Cmcm of the orthorhombic system with four formula units in a cell. Cell constants (Å) at 153 K are: β-LaYbS 3, 3.9238(8), 12.632(3), 9.514(2); LaYbSe 3, 4.0616(8), 13.094(3), 9.932(2); CeYbSe 3, 4.0234(5), 13.065(2), 9.885(1); PrYbSe 3, 4.0152(5), 13.053(2), 9.868(1); NdYbSe 3, 4.0015(6), 13.047(2), 9.859(1); SmYbSe 3, 3.9780(9), 13.040(3), 9.860(2). The structure is composed of layers of Yb Q6 ( Q=S or Se) octahedra that alternate with layers of LnQ8 bicapped trigonal prisms along the b-axis. Because there are no Q- Q bonds in the structure the formal oxidation states of Ln/Yb/ Q are 3+/3+/2−. Magnetic susceptibility measurements indicate that CeYbSe 3 and SmYbSe 3 are Curie-Weiss paramagnets over the temperature range 5-300 K. 相似文献
5.
The new compound MnSbS 2Cl was synthesised from a mixture of MnS, MnCl 2 and Sb 2S 3 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 MnSbS 2Cl is isotypic with stibnite Sb 2S 3 and consists of waved layers of corner-sharing MnS 4Cl 2 octahedra along the a axis and edge-sharing octahedra along the b axis, which are separated by antimony atoms. MnSbS 2Cl susceptibility shows an antiferromagnetic behaviour below 40 K with an increase at about 23 K. 相似文献
6.
Single crystals of CsHo 3Te 5 and Cs 3Tm 11Te 18 have been grown as byproducts in the synthesis of Cs LnZnTe 3 ( Ln=Ho or Tm) through the reaction of Ln, Zn, and Te with a CsCl flux at 850 °C. The crystal structures have been determined from single-crystal X-ray diffraction data. CsHo 3Te 5 crystallizes in space group Pnma of the orthorhombic system whereas Cs 3Tm 11Te 18 crystallizes in the space group C2 /m of the monoclinic system. Each of the compounds adopts a three-dimensional structure; each possesses tunnels built from LnTe 6 octahedra that are filled with Cs atoms. The pseudo-rectangular tunnel in CsHo 3Te 5 is large enough in cross-section to accommodate two symmetrically equivalent Cs atoms. In the Cs 3Tm 11Te 18 structure there are two different sized tunnels: the smaller one is only large enough to host one Cs atom per unit cell whereas the larger one can accommodate two Cs atoms. The electronic structure of CsHo 3Te 5 was calculated. The band gap is estimated to be about 1.2 eV, consistent with the black color of the crystals. 相似文献
7.
Two new quaternary salts, [Hg 3Te 2][UCl 6] and [Hg 4As 2][UCl 6], have been synthesized and their structures determined by single-crystal X-ray diffraction analysis. [Hg 3Te 2][UCl 6] is the product of a reaction involving UCl 4, HgCl 2, and HgTe at 873 K. The compound crystallizes in space group P2 1/ c of the monoclinic system. [Hg 4As 2][UCl 6] results from the reaction of U, Hg 2Cl 2, and As at 788 K. It crystallizes in space group Pbca of the orthorhombic system. [Hg 3Te 2][UCl 6] has a two-dimensional framework of layers, whereas [Hg 4As 2][UCl 6] has a three-dimensional framework of layers interconnected by Hg atoms linearly bonded to As atoms. Both framework structures contain discrete [UCl 6] 2− anions between the layers. [Hg 3Te 2][UCl 6] exhibits temperature-independent paramagnetism. The optical absorption spectra of these compounds display f- f transitions. 相似文献
8.
The crystal structure of Sr 4Mn 2NiO 9 has been refined on single crystal. This phase belongs to the series A 1+x(A ′xB 1–x)O 3 ( 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. Sr 4Mn 2NiO 9 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 Ni 2+ ions in the spin state configuration S=0. 相似文献
9.
The (NH 4) 0.80Li 0.20[Fe(AsO 4)F] compound has been synthesized under mild hydrothermal conditions. The compound crystallize in the orthorhombic Pna2 1 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(PO 4) structure type, with chains alternating FeO 4F 2 octahedra and AsO 4 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
10.
The ternary selenides LnCuSe 2 ( Ln=La, Ce, Pr, Nd, Sm) have been synthesized by the reaction at 1173 K of Ln, Cu, and Se in a KBr or KI flux. The compounds, which are isostructural with LaCuS 2, crystallize with four formula units in the space group P2 1/ c of the monoclinic system. The structure may be thought of as consisting of layers of CuSe 4 tetrahedra separated by double layers of LnSe 7 monocapped trigonal prisms along the a-axis. Cell constants (Å or deg) at 153 K are: LaCuSe 2, 6.8142(5), 7.5817(6), 7.2052(6), 97.573(1)°; CeCuSe 2, 6.7630(5), 7.5311(6), 7.1650(6), 97.392(1)°; PrCuSe 2, 6.740(1), 7.481(1), 7.141(1), 97.374(2)°; NdCuSe 2, 6.7149(6), 7.4452(7), 7.1192(6), 97.310(1)°; SmCuSe 2, 6.6655(6), 7.3825(7), 7.0724(6), 97.115(1)°. There are no Se-Se bonds in the structure of LnCuSe 2; the formal oxidation states of Ln/Cu/Se are 3+/1+/2−. 相似文献
11.
The synthesis, crystal structure and magnetic properties are reported for the new bimetallic compound {(CuL 1)[Co(NCS) 4]} where L 1 = N- rac-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. The complex forms a one-dimensional zig-zag coordination polymer along the crystallographic c axis, with Co(II) and Cu(II) ions connected via thiocyanate bridges. The Co(II) centre in the [Co(NCS) 4] fragment approximates a distorted tetrahedral symmetry. The Cu(II) geometry is a distorted tetragonal bipyramid with the apical position occupied by the bridging thiocyanate ligand and the basal ones by the four nitrogen atoms from the macrocyclic ring. The polymer chain nearest Cu(1)?Co(1) distances are 6.4152(9) and 6.0988(9) Å and the nearest Cu(1)?Co(1) interchain distances are 6.8609(9), 6.9628(9) and 6.0336(10) Å. The magnetization measurements for the examined compound have been carried out over the range 1.8–300 K. This data suggest ferromagnetic interactions through the thiocyanate bridge. 相似文献
12.
The synthesis, crystal structure and magnetic measurements of three new polynuclear tetracarboxylato-bridged copper(II) complexes, i.e. {[Cu 4(phen) 2(μ-O 2CC 2H 5) 8] · (H 2O)} n (1), [Cu 2(μ-O 2CC 6H 4OH) 4(C 7H 7NO) 2] · 6H 2O (2) and [Cu 2(μ-O 2CCH 3) 4(C 7H 7NO) 2] (3) (phen = 1,10-phenanthroline, O 2CC 6H 4OH = 3-hydroxy benzoate, C 7H 7NO = 4-acetylpyridine) are reported. All compounds consist of dinuclear units, in which two Cu(II) ions are bridged by four syn, syn-η 1:η 1:μ carboxylates, showing a paddle-wheel cage type with a square-pyramidal geometry, arranged in different ways. The structure of compound 1 consists of an one-dimensional structure generated by an alternating classical dinuclear paddle-wheel unit and an unusual dinuclear Cu 2(μ-OCOC 2H 5) 2(μ-O 2CC 2H 5) 2(phen) 2unit, which are connected to each other via a syn, anti-triatomic propionato bridge in an axial-equatorial configuration. The adjacent chains are connected to generate a 2D structure through the face-to-face π–π interaction between phen rings. Structures of compounds 2 and 3 both consist of a symmetric dinuclear Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of 4-acetylpyridine ligand at the apical position, and just differ in the substituents of the equatorial ligands. The magnetic properties have been measured and correlated with the molecular structures. It is found that in the two classical paddle-wheel compounds the Cu(II) ions are strongly antiferromagnetically coupled with J = −278.5 and −287.0 cm−1 for complexes 2 and 3, respectively. In compound 1 the magnetic susceptibility could be fitted with two different, independent Cu(II) units, one strongly coupled and one weakly coupled; the paddle-wheel dinuclear unit has the strongest antiferromagetic coupling with a value for J of −299.5 cm−1, whereas the Cu(II) ions in the propionato-bridged dinuclear unit of 1 display a very weak antiferromagnetic coupling with a value for J = −0.75 cm−1, due to the orthogonality of the magnetic orbitals. Also the exchange within the chain is therefore very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes. 相似文献
13.
Two novel metal sulfur chlorides - Zn 6S 5Cl 2 ( 1) and Hg 3ZnS 2Cl 4 ( 2) - were obtained by solid-state reactions and structurally characterized by single-crystal X-ray diffraction. Compound 1 is characteristic of a 1-D tunnel-like structure, which connects to each other to construct a 3-D framework with the chlorine atoms locating at the voids. Compound 2 crystallizes in the acentric space group P6 3mc of the hexagonal system. Compound 2 features a 2-D layered motif, which is composed by the interconnected 12-membered Hg 6S 3Cl 3 rings with chair-like conformation. There are ZnSCl 3 tetrahedra located between the layers, yielding a sandwich-like structure. TG-DTA measurement shows that compound 1 is thermally stable up to 220 °C. Optical absorption spectra reveal the presence of sharp optical gap of 2.71 and 2.65 eV for 1 and 2, respectively. 相似文献
14.
Three new ternary potassium(I) zinc(II) or cadmium(II) tellurides, namely, K 2Cd 2Te 3, K 6CdTe 4 and K 2ZnTe 2, were synthesized by solid-state reactions of the mixture of pure elements of K, Cd (or Zn) and Te in Nb tubes at high temperature. K 2Cd 2Te 3 belongs to a new structure type and its structure contains a novel two-dimensional [Cd 2Te 3] 2− layers perpendicular to the b-axis. K(5) cation is located at the center of five member rings of the 2D [Cd 2Te 3] 2− layer, whereas other K + cations occupy the interlayer space. K 6CdTe 4 with a K 6HgS 4 type structure features a “zero-dimensional” structure composed of isolated CdTe 4 tetrahedra separated by the K + ions. K 2ZnTe 2 in the K 2ZnO 2 structural type displays 1D [ZnTe 2] 2− anionic chains of edge sharing [ZnTe 4] tetrahedra separated by the potassium(I) ions. K 2Cd 2Te 3, K 6CdTe 4 and K 2ZnTe 2 revealed a band gap of 1.93, 2.51 and 3.0 eV, respectively. 相似文献
15.
Three new compounds, Cs 2Bi 2ZnS 5, Cs 2Bi 2CdS 5, and Cs 2Bi 2MnS 5, have been synthesized from the respective elements and a reactive flux Cs 2S 3 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) Å 3 for Cs 2Bi 2ZnS 5; a=15.817(2), b=4.1782(6), c=18.473(3) Å, V=1220.8(3) Å 3 for Cs 2Bi 2CdS 5; and a=15.830(2), b=4.1515(5), c=18.372(2) Å, V=1207.4(2) Å 3 for Cs 2Bi 2MnS 5. The structure is composed of two-dimensional ∞2[Bi 2MS 52−] ( 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[Bi 2S 66−] and ∞1[ MS 34−] chains built from BiS 6 octahedral and MS 4 tetrahedral units. Two crystallographically unique Cs atoms are coordinated to S atoms in octahedral and monocapped trigonal prismatic environments. The structure of Cs 2Bi 2MS 5, is related to that of Na 2ZrCu 2S 4 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 Cs 2Bi 2ZnS 5 and Cs 2Bi 2CdS 5 are semiconductors with indirect band gaps of 1.85 and 1.75 eV, respectively. The experimental band gap for Cs 2Bi 2CdS 5 is ≈1.7 eV, as derived from its optical absorption spectrum. 相似文献
16.
Two new complexes [Ni(pydc)(H 2O) 2] n (1) and [Ni 2(pydc) 2(H 2O) 5] n (2) (H 2pydc = 2,4-pyridinedicarboxylic acid) have been obtained by hydrothermal synthetic method and characterized by single crystal X-ray analysis. In 1 six-coordinate Ni(II) ions are coordinated by pydc ligands to form 2-D layer structures; while in 2 six-coordinate Ni(II) ions are only connected into 1-D zigzag chains constructed by dinuclear nickel units. Although the coordination geometries around Ni(II) centers in both complexes are similar, their structure topologies are greatly tuned by coordination modes of pydc. Variable temperature magnetic susceptibility studies have shown that both compounds 1 and 2 may display antiferromagnetic coupling between paramagnetic metal centers mediated by bridging carboxylate groups. 相似文献
17.
The ternary copper indides RE2CuIn 3≡ RECu 0.5In 1.5 ( RE=Ce, Pr, Nd, Sm and Gd) were synthesized from the elements in sealed tantalum tubes in an induction furnace. They crystallize with the CaIn 2-type structure, space group P6 3/ mmc, with a statistical occupancy of copper and indium on the tetrahedral substructure. These indides show homogeneity ranges RECu xIn 2−x. Single crystal structure refinements were performed for five crystals: CeCu 0.66In 1.34 ( a=479.90(7) pm, c=768.12(15) pm), PrCu 0.52In 1.48 ( a=480.23(7) pm, c=759.23(15) pm), NdCu 0.53In 1.47 ( a=477.51(7) pm, c=756.37(15) pm), SmCu 0.46In 1.54 ( a=475.31(7) pm, c=744.77(15) pm), and GdCu 0.33In 1.67 ( a=474.19(7), c=737.67(15) pm). Temperature-dependent susceptibility measurements show antiferromagnetic ordering at TN=4.7 K for Pr 2CuIn 3 and Nd 2CuIn 3 and 15 K for Sm 2CuIn 3. Fitting of the susceptibility data of the samarium compound revealed an energy gap Δ E=39.7(7) K between the ground and the first excited levels. 相似文献
18.
Three new uranyl tungstates, A8[(UO 2) 4(WO 4) 4(WO 5) 2] ( A=Rb ( 1), Cs ( 2)), and Rb 6[(UO 2) 2O(WO 4) 4] ( 3), were prepared by high-temperature solid-state reactions and their structures were solved by direct methods on twinned crystals, refined to R1=0.050, 0.042, and 0.052 for 1, 2, and 3, respectively. Compounds 1 and 2 are isostructural, monoclinic P2 1/ n, ( 1): a=11.100(7), b=13.161(9), , β=90.033(13)°, , Z=8 and ( 2): , , , β=89.988(2)°, , Z=8. There are four symmetrically independent U 6+ sites that form linear uranyl [O=U=O] 2+ cations with rather distorted coordination in their equatorial planes. There are six W positions: W(1) and W(2) have square-pyramidal coordination (WO 5), whereas W(3), W(4), W(5), and W(6) are tetrahedrally coordinated. The structures are based upon a novel type of one-dimensional (1D) [(UO 2) 4(WO 4) 4(WO 5) 2] 4− chains, consisting of WU 4O 25 pentamers linked by WO 4 tetrahedra and WO 5 square pyramids. The chains run parallel to the a-axis and are arranged in modulated pseudo-2D-layers parallel to (0 1 0). The A + cations are in the interlayer space between adjacent pseudo-layers and provide a 3D integrity of the structures. Compounds 1 and 2 are the first uranyl tungstates with 2/3 of W atoms in tetrahedral coordination. Such a high concentration of low-coordinated W 6+ cations is probably responsible for the 1D character of the uranyl tungstate units. The compound 3 is triclinic, P1¯ a=10.188(2), b=13.110(2), , α=97.853(3), β=96.573(3), γ=103.894(3)°, , Z=4. There are four U positions in the structure with a typical coordination of a pentagonal bipyramid that contain uranyl ions, UO 22+, as apical axes. Among eight W sites, the W(1), W(2), W(3), W(4), W(5), and W(6) atoms are tetrahedrally coordinated, whereas the W(7) and W(8) cations have distorted fivefold coordination. The structure contains chains of composition [(UO 2) 2O(WO 4) 4] 6− composed of UO 7 pentagonal bipyramids and W polyhedra. The chains involve dimers of UO 7 pentagonal bipyramids that share common O atoms. The dimers are linked into chains by sharing corners with WO 4 tetrahedra. The chains are parallel to [−101] and are arranged in layers that are parallel to (1 1 1). The Rb + cations provide linkage of the chains into a 3D structure. The compound 1 has many structural and chemical similarities to its molybdate analog, Rb 6[(UO 2) 2O(MoO 4) 4]. However, the compounds are not isostructural. Due to the tendency of the W 6+ cations to have higher-than-fourfold coordination, part of the W sites adopt distorted fivefold coordination, whereas all Mo atoms in the Mo compound are tetrahedrally coordinated. Distribution of the WO 5 configurations along the chain extension does not conform to its ‘typical’ periodicity. As a result, both the chain identity period and the unit-cell volume are doubled in comparison to the Mo analog, which leads to a new structure type. 相似文献
19.
RbVSe 2 has been synthesized at 773 K through the reaction of V and Se with a Rb 2Se 3 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 VSe 4 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 V 3+ cations is the most stable. 相似文献
20.
CuSbTeO 3Cl 2 has been isolated during an investigation of the system Cu 2O:TeCl 4:Sb 2O 3:TeO 2. The new compound is light yellow and crystallises in the monoclinic system, space group C2/ m, a=20.333(5) Å, b=4.0667(9) Å, c=10.778(2) Å, Z=6. The structure is layered and is built up from corner and edge sharing [(Sb,Te)O 4E] trigonal bipyramids that have the lone pair (E) directed towards one of the equatorial positions, those groups build up [(Sb,Te) 2O 3E 2+] n layers. The copper and the chlorine atoms are located in between those layers. There are two different Cu positions. The [Cu1Cl 4] group is a slightly distorted tetrahedron and these tetrahedra make up chains by corner sharing. The electron density for the half occupied Cu2 atom is spread out in the structure like a worm that run along the b-axis in the space in between two chains of [Cu1Cl 4] tetrahedrons. Analysis of the diamagnetic response in magnetic susceptibility measurements is in perfect agreement with a Cu + valence. Conductivity measurements in the temperature range 355–590 K gives an activation energy of 0.55 eV. The delocalised Cu2 position in the structure suggests that the compound is a Cu + ionic conductor along the b-axis. 相似文献
|