共查询到20条相似文献,搜索用时 15 毫秒
1.
Qingbiao Zhao 《Materials Research Bulletin》2011,46(2):166-169
Crystals of K2Hf2O5 and K4Hf5O12 were grown from molten potassium hydroxide flux. The crystal structures were determined by single-crystal X-ray diffraction. K2Hf2O5 crystallizes in the space group Pnna of the orthorhombic system, with unit cell dimensions of a = 5.780(1) Å, b = 10.640(2) Å, and c = 8.666(2) Å. This compound contains infinite chains of HfO6 octahedra that form a channel structure. K4Hf5O12 crystallizes in the space group of the trigonal system, with unit cell dimensions of a = 5.7877(2) Å and c = 10.3693(7) Å. This compound possesses a layered structure with six-coordinate Hf in three different coordination environments (trigonal prismatic, distorted octahedral, and regular octahedral). 相似文献
2.
The crystal structure of Pb3BiV3O12 was solved using single-crystal X-ray diffraction technique. The compound crystallizes in the cubic system (No. 220) with eulytite structure with a = 10.7490(7) Å, V = 1241.95(14) Å3 and Z = 4. The final R1 value of 0.0198 (wR2=0.0384) was achieved for 359 independent reflections during the structure refinement. The Pb2+ and Bi3+ cations occupy the special position (16c) while the oxygen anions occupy the general position (48e) in the crystal structure. Unlike many other eulytite compounds, all the crystallographic positions are fully occupied. The structure consists of edge-shared Pb/Bi octahedra linked at the corners to independent [VO4]3− tetrahedra units, generating a eulytite-type network in the crystal lattice. 相似文献
3.
L. Guelmami 《Materials Research Bulletin》2009,44(3):549-554
Structural properties of the 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate are discussed on the basis of an X-ray structure investigation. (C4H8N5)2H2P2O7·2H2O is monoclinic, C2/c, with a = 10.414(1) Å, b = 13.365(1) Å, c = 13.736(2) Å, β = 98.39(4)°, and Z = 4. The structure has been solved by a direct method and refined to a reliability R factor of 0.0375 (Rw = 0.0961) using 2751 independent reflections. The structural arrangement can be described as inorganic infinite ribbons, , spreading along the c direction; the organic groups, [C4H8N5]+, link the precedent ribbons, via their hydrogen bonds, to form a three-dimensional network. The present work, deals with crystal structure, thermal behavior and IR analysis of this new compound. 相似文献
4.
Noura Jouini 《Materials Research Bulletin》2007,42(1):56-63
Crystals of a new organic compound, the isonicotinic acid hydrazide dihydrogendiphosphate, (C6H9N3O)H2P2O7 (denoted INHDP) were prepared and grown at room temperature. The INHDP crystallizes in the triclinic system with the space group. Its unit cell dimensions are: a = 7.316(3) Å, b = 7.783(3) Å, c = 10.802(4) Å, α = 82.41(3)°, β = 75.19(3)°, γ = 72.57(3)°, with V = 566.3(4) Å3 and Z = 2. Crystal structure has been determined and refined to a reliability R factor of 0.0389. The atomic arrangement can be described as inorganic infinite ribbons of H2P2O72− anions spreading parallel to the b-axis. These ribbons are themselves interconnected by the organic (C6H9N3O)+ cations so as to build a three dimensional arrangement. In the present work, we describe the crystal structure, thermal behaviour and IR analysis of this new compound. 相似文献
5.
Chemical preparation, crystal structure, calorimetric studies and spectroscopic investigation are given for a new organic cation dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2. This compound is triclinic with the following unit cell parameters: a=9.030(6) Å, b=16.124(5) Å, c=8.868(3) Å, α=75.04(3)°, β=110.71(4)°, γ=104.61(1)°, Z=4, V=1148.0(1) Å3, Z=2 and ρcal.=1.454 g cm−3. Crystal structure was solved and refined to R=0.04, 2752 independent reflections. The atomic arrangement can be described as inorganic layers of H2PO4− anions parallel to planes, between which are located the organic groups. Solid-state and MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups. 相似文献
6.
Transformation of Dion-Jacobson phase to Aurivillius phase: synthesis of (PbBiO2)MNb2O7 (M = La, Bi)
T. Sivakumar 《Materials Research Bulletin》2005,40(1):39-45
We describe transformations of the Dion-Jacobson (D-J) phases, KLaNb2O7 and RbBiNb2O7, to the Aurivillius (A) phases, (PbBiO2)LaNb2O7 (1) and (PbBiO2)BiNb2O7 (2), in a metathesis reaction with PbBiO2Cl. Oxide 1 adopts centrosymmetric tetragonal structure (a = 3.905(1) Å, c = 25.66(1) Å), whereas oxide 2 crystallizes in a noncentrosymmetric orthorhombic (A21am) (a = 5.489(1) Å, b = 5.496(2) Å, c = 25.53(1) Å) structure. Oxide 2 shows a distinct SHG response towards 1064 nm laser radiation. The role of La3+ versus Bi3+ in the perovskite slabs for the occurrence of noncentrosymmetric structure/ferroic property in these materials is pointed out. 相似文献
7.
Synthesis, crystal structure, vibrational study, 13C, 111Cd CP-MAS-NMR analysis and electrical properties of the compound [N(C3H7)4]2Cd2Cl6, are reported. The latter crystallizes in the triclinic system (space group , Z = 2) with the following unit cell dimensions: a = 9.530(1) Å, b = 11.744(1) Å, c = 17.433(1) Å, α = 79.31(1)°, β = 84.00(1)° and γ = 80.32(1)°. Besides, its structure was solved using 6445 independent reflections down to R = 0.037. The atomic arrangement can be described by alternating organic and inorganic layers parallel to the plan, made up of tetrapropylammonium groups and Cd2Cl6 dimers, respectively. In crystal structure, the inorganic layer, built up by Cd2Cl6 dimers, is connected to the organic ones through van der Waals interaction in order to build cation-anion-cation cohesion. Impedance spectroscopy study, reported in the sample, reveals that the conduction in the material is due to a hopping process. The temperature and frequency dependence of dielectric constants of the single crystal sample has been investigated to determine some related parameters to the dielectric relaxation. 相似文献
8.
Crystals of RbPrHP3O10 have been grown by the flux technique and characterized by single-crystal X-ray diffraction. RbPrHP3O10 crystallizes in the triclinic space group with lattice parameters: a = 7.0655(5), b = 7.7791(4), c = 8.6828(6) Å, α = 74.074(3), β = 74.270(3), γ = 82.865(2)°, V = 441.09(5) Å3, Z = 2. The crystal structure has been solved yielding a final R(F2) = 0.0443 and Rw(F2) = 0.1426 for 1955 independent reflections (Fo2 ≥ 2σ(Fo2)). The structure of RbPrHP3O10 consists of PrO8 polyhedra and P3O105− groups sharing oxygen atoms to form a two-dimensional framework; the PrO8 polyhedra form infinite chains by edge-sharing. Each Rb+ ion is bonded to 10 oxygen atoms, these ions are located between chains formed of (HP3O10)4−. The energies of the vibrational modes of the crystal were obtained from measurements of the infrared spectrum. 相似文献
9.
The structures of two intercalation compounds, Ge∼0.2NbSe2 and Ge∼0.3NbS2 were investigated by single crystal X-ray diffraction and electron microscopy (selected area electron diffraction (SAED), high resolution electron microscopy (HRTEM) and X-ray microanalysis by energy dispersive spectroscopy (XEDS)). Crystal structure determinations of the average structure of the intercalation compounds 2H-Ge0.217NbSe2 and 4H-Ge0.288NbS2 are reported: the selenide compound crystallizes in the space group P63/mmc with a = 3.4560(9) Å and c = 12.966(3) Å and adopts the 2H-NbSe2 structure-type, while the sulfide compound crystallizes in the P63mc space group, with a = 3.3392(9) Å and c = 25.404(7) Å with a structure-type 4Hc-NbS2 which it is known for TaSe2. In both structures the germanium atoms are located in the empty octahedral positions of the van der Waals gap between the NbX2 (X = S, Se) layers. Electron diffraction patterns from several GexNbSe2 crystal flakes show different superstructures and exhibit diffracted diffuse intensity: weak satellites corresponding to and 2a0 × 2a0 superstructures were observed for x ∼ 0.15 (a0 is the basal lattice parameter of the host structure). For x ∼ 0.25-0.33, the same type of satellite is observed with a stronger intensity. For x ∼ 0.5 only satellites corresponding to the superstructure were present. In the case of GexNbS2, with 0.10 < x < 0.25, the germanium atoms are ordered in domains with an superstructure. In some crystals disorder along the c-axis has been observed. 相似文献
10.
11.
Chemical preparation and crystal structure are reported for a new lanthanide cyclotriphosphate Na3Yb(P3O9)2·9H2O. This salt crystallizes in the trigonal system, space group with the following parameters: a = 30.933(2), c = 12.8282(5) Å. The crystal structure was refined to R1 = 0.0432 using 1782 reflections with I > 2 σ(I). In the Na3Yb(P3O9)2·9H2O structure, the phosphoric ring anions, located around the axis are interconnected by YbO8 dodecahedra and NaO6 and NaO7 polyhedra to build, around the threefold axis, large channels parallel to the c axis. All the nine water molecules in the present arrangement participate in the coordination spheres of the associated cations. The thermogravimetric analysis shows that the removal of these water molecules occurs in three stages between 305 and 736 K.The vibrational study by IR absorption spectroscopy of Na3Yb(P3O9)2·9H2O is also reported. 相似文献
12.
N. Kumada T. Takei Y. Yonesaki N. Kinomura Y. Kameshima 《Materials Research Bulletin》2011,46(6):962-965
Single crystals of a new bismuth vanadate, Bi3.33(VO4)2O2 was prepared by hydrothermal reaction using a hydrated sodium bismuthate, NaBiO3·nH2O as one of the starting compounds. The crystal structure was determined by using single crystal X-ray diffraction data. This compound crystallizes in the triclinic space group (#2) with a = 7.114(1), b = 7.844(2), c = 9.372(2) Å, α = 106.090(7), β = 94.468(7) and γ = 112.506(8)°, Z = 2 and the final R factors are R1 = 0.052 and wR2 = 0.14 for 2085 unique reflections. The crystal structure is composed by four bismuth atoms with the coordination number of 6 or 8 and two VO4 tetrahedra, and one of four bismuth atoms is statistically distributed in the splitting sites with the distance of 0.83 Å. This compound exhibited photocatalytic behavior for decomposition of phenol under visible light irradiation and its activity was less than that of monoclinic BiVO4. 相似文献
13.
Ya-Xi Huang 《Science and Technology of Advanced Materials》2007,8(5):399-405
The organo-templated iron(III) borophosphate (C4H12N2)3FeIII6(H2O)4[B6P12O50(OH)2]·2H2O was prepared under mild hydrothermal conditions (443 K). The crystal structure was determined from single-crystal X-ray data at 295 K (orthorhombic, Pbca (No. 61), Z=4, a=17.8023(7) Å, b=16.1037(5) Å, c=19.1232(6) Å, V=5482.3(3) Å3, R1=0.055, wR2=0.104, 6576 observed reflections with I>2σ(I)) and contains a new type of borophosphate anion: a mixed open- and loop-branched zehner single chain, , built from heptamers [B2P5O21] interconnected by BO3(OH) tetrahedra sharing their third oxygen corners with additional (terminal) PO4 tetrahedra to form open branchings. The mixed open- and loop-branched single chains running along [0 0 1] are interconnected by three crystallographically independent iron coordination octahedra to form a 3D framework structure containing eight-membered ring channels running along [0 1 0] and cages, which are occupied by two crystallographically independent piperazine cations and H2O molecules. The displacement parameters of C and N atoms in the piperazine cations are dramatically influenced by the strength of the hydrogen bond reflecting the shape of the cavities. The magnetic investigations indicate the existence of antiferromagnetic interactions as the major components. A narrow hysteresis at low temperatures indicates a weak ferromagnetic component, due to a non-cancellation of spins. 相似文献
14.
The phase diagram of the Ag2Se-Ho2Se3 system in the range of 0-50 mol.% Ho2Se3 was constructed with the results of XRD and differential thermal analysis. A dimorphous compound exists in the system at the equimolar ratio of the components. The investigated part of the Ag2Se-AgHoSe2 diagram is of the eutectic type with the eutectic coordinates 7 mol.% Ho2Se3 and 1125 K. The crystal structure of the high-temperature modification of AgHoSe2 was studied by X-ray powder diffraction method. α-AgHoSe2 is described as a NaCl structure (space group ) with the lattice parameter а = 5.7623(3) Å. Atomic parameters were calculated in the isotropic approximation (RI = 0.0434 and RР = 0.0636). The crystal structure of β-AgHoSe2 was determined by X-ray structure analysis and was refined to R = 0.0487. 相似文献
15.
Laurent Cario Alain Meerschaut Benoît Corraze Olivier Chauvet 《Materials Research Bulletin》2005,40(1):125-133
Single crystal X-ray diffraction was used to determine the modulated structure of the misfit layer compound (LaS)1.196VS2. This compound crystallizes in the triclinic system with cell parameters: as = 3.410 (1) Å, bs = 5.845(1) Å, cs = 11.191(2) Å, α ≈ 95.15(4), β ≈ 84.79(2)°, and γ ≈ 89.98(2)°, q = 0.5978(4)as* − 0.002(1)bs* + 0.004(2)cs*, and Vs = 221.2(1) Å3. A (3 + 1)D superspace group, X(α,β,γ), was used to analyze the complete structure (X is referring to a pseudo C centering). The largest modulation amplitudes are observed for La-S (between La (subsystem 2) and S (subsystem 1)), as well as V-V distances. In connection with the large V-V modulation, we observed the formation of “linear vanadium clusters” that may impact on the transport properties. 相似文献
16.
A lithium bismuth phosphate, Li2Bi14.67(PO4)6O14, has been synthesized for the first time by the solid-state method. The crystal structure was determined by single crystal X-ray diffraction at 150 K. Li2Bi14.67(PO4)6O14 crystallizes in the monoclinic system C2/c (No. 15), with a = 30.8189(4) Å, b = 5.2691(3) Å, c = 24.5302(3) Å, β = 122.84(2)°, V = 3346.81(1) Å3 and Z = 2. The structure along the b axis consists of layers of [Bi2O2] units as the basic building block. These are separated by isolated PO4 and LiO4 tetrahedra. The oxygen co-ordination around two of the phosphorus atoms is disordered. Solid-state 7Li NMR studies confirm the presence of lithium in the structure. The material shows ionic conductivity of the order of 10−5 S cm−1 at 600 °C. 相似文献
17.
Cobalt ethylenediammonium bis(sulfate) tetrahydrate, [NH3(CH2)2NH3][Co(SO4)2(H2O)4], has been synthesised by slow evaporation at room temperature. It crystallises in the triclinic system, space group , with the unit cell parameters: a = 6.8033(2), b = 7.0705(2), c = 7.2192(3) Å, α = 74.909(2)°, β = 72.291(2)°, γ = 79.167(2)°, Z = 1 and V = 317.16(2) Å3. The Co(II) atom is octahedrally coordinated by four water molecules and two sulfate tetrahedra leading to trimeric units [Co(SO4)2(H2O)4]. These units are linked to each other and to the ethylenediammonium cations through OW-H…O and N-H…O hydrogen bonds, respectively. The zero-dimensional structure is described as an alternation between cationic and anionic layers along the crystallographic b-axis. The dehydration of the precursor proceeds through three stages leading to crystalline intermediary hydrate phases and an anhydrous compound. The magnetic measurements show that the title compound is predominantly paramagnetic with weak antiferromagnetic interactions. 相似文献
18.
19.
Cu2MnTi3S8 and Cu2NiTi3S8 compounds were prepared by high-temperature synthesis. The crystal structure of these quaternary phases was investigated by X-ray powder diffraction. The compounds are described in the thiospinel structure (space group ) with the lattice constants a = 1.00353(1) nm (Cu2MnTi3S8) and a = 0.99716(1) nm (Cu2NiTi3S8). The atomic parameters were calculated in anisotropic approximation (RI = 0.0456 and RI = 0.0520 for Cu2MnTi3S8 and Cu2NiTi3S8, respectively). 相似文献
20.
Yang-Yang Zhang 《Materials Research Bulletin》2007,42(8):1531-1538
A new iron phosphonate-oxalate [Fe(O3PCH3)(C2O4)0.5(H2O)] (1), has been synthesized under hydrothermal condition. The single-crystal X-ray diffraction studies reveal that 1 consists of layers of vertex-linked FeO6 octahedra and O3PC tetrahedra, which are further connected by bis-chelate oxalate bridges, giving to a 3D structure with 10-membered channels. Crystal data: monoclinic, P21/n (no. 14), a = 4.851(2) Å, b = 16.803(7) Å, c = 7.941(4) Å, β = 107.516(6)°, V = 617.2(5) Å3, Z = 4, R1 = 0.0337 and wR2=0.0874 for 1251 reflections [I > 2σ(I)]. Mössbauer spectroscopy measurement confirms the existence of high-spin Fe(III) in 1. Magnetic studies show that 1 exhibits weak ferromagnetism with TN = 30 K due to a weak spin canting. 相似文献