The crystal structure of LiScS2 and NaScS2

LiScS₂ and NaScS₂ were prepared and the structure was determined by X-ray powder work. The observed α-NaFeO₂ structure for these compounds is discussed in relation to other ABS₂ compounds.     

Synthesis and crystal structure of InP3

Higher indium phosphide InP₃ is obtained under high pressure of 3 GPa at 1200°C. The crystal structure was analyzed to be isomorphous with SnP₃, and GeP₃ having lattice parameters of $\text{a}\text{= 7.449}\text{A}\text{?}$ and $\text{c}\text{= 9.885}\text{A}\text{?}$. InP₃ is a metallic conductor although it is less in the amount of valence electrons than its isomorphous MP₃ of Ge and of Sn.     

The crystal structure of the intercalates SnTaS2 and SnNbS2

The crystal structure of SnTaS₂ was determined by X-ray and neutron powder diffraction. SnTaS₂ is hexagonal, $\text{a}\text{=3.307}\text{A}\text{?}$, $\text{c}\text{=17.442}\text{A}\text{?}$, space group P6₃/mmc with Ta and Sn at special positions. Ta is in trigonal-prismatic coordination by sulfur forming TaS₂ slabs; Sn is linearly coordinated by sulfur atoms of adjacent TaS₂ slabs. X-ray powder diffraction showed that SnNbS₂ is isostructural with SnTaS₂.     

Synthesis and crystal structure of the inter-alkali metal iodide Cs2Li3I5

Cs₂Li₃I₅ was obtained from the reaction of CsI, Li and I₂ in a sealed tantalum tube and colorless single crystals grown from the melt by slow cooling. This first inter-alkali metal iodide crystallizes in the monoclinic crystal system (C2/m, Z= 2) with a= 1666.8(6), b= 472.1(1), c= 1098.7(4) pm, β= 115.73(3)°. As the result of a x-ray crystallographic structure determination (R= 0.069, R_W= 0.066), Li⁺ is surrounded tetrahedrally (two thirds) and octahedrally (one third) by iodide. Cornersharing double chains of [LiI₄] tetrahedra are connected with edge-sharing chains of [LiI₆] octahedra to a layer of the composition [Li₃I₅]. Bicapped trigonal prisms [CsI₃] share faces and edges so that a network of the composition [Cs₂I₅] is formed which contains the necessary tetrahedral and octahedral holes for Li⁺.     

Synthesis and crystal structure of triphosphate RbPrHP3O10

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) ų, Z = 2. The crystal structure has been solved yielding a final R(F²) = 0.0443 and R_w(F²) = 0.1426 for 1955 independent reflections (F_o² ≥ 2σ(F_o²)). 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.     

Symmetry and crystal structure of Ti3SiC2

Convergent beam electron diffraction (CBED) and X-ray diffractometry (XRD) have been used to examine the symmetry, structure and lattice parameters of Ti₃SiC₂. The CBED analysis confirms that the material is hexagonal with a point group of 6/mmm. The XRD diffraction peak positions and intensities are in good agreement with calculations based on previously proposed atomic positions.     

The crystal structure of Li2MoF6

Crystals of Li₂MoF₆ are tetragonal P4₂2₁2 with a_o = 4.6863(7) and c_o = 9.191(2)A, Z = 2 and the calculated density is 3.687 g/cc. The Li⁺ and Mo⁴⁺ ions are octahedrally coordinated. The Li-F distances range from 2.017(2) to 2.102(7)A and the Mo-F distances range from 1.927(2) to 1.945(2)A. The MoF₆^-- ion is coordinated by 10 Li⁺.     

Redetermination of the crystal structure of Cs2AuAuCl6

The structure of Cs₂AuAuCl₆ is redetermined using single crystal X-ray analysis. The overall structure is in accordance with the one proposed by Elliott and Pauling in J.Am. Chem. Soc. $\text{60}$, 1846 (1938). The spacegroup is I4/mmm with axes $\text{a}\text{=7.495(1)}\text{A}\text{?}$ and $\text{c}\text{=10.880(2)}\text{A}\text{?}$, Z=2.The shortest gold-chlorine distances are 2.281(2)Å in the linear [Au(I)Cl₂]^? and 2.295(2)Å in the square planar [Au(III)Cl₄]^? unit. The last figure as contrasted to the value of 2.42Å found by Elliott and Pauling.     

Synthesis and crystal structure of Cu2NiO(B2O5) and Cu2MgO(B2O5)

A transport reaction synthesis technique has been used to prepare single crystals of two pyroborate compounds having the formulas Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅). The two compounds are isostructural and crystallize in the monoclinic space group P2₁/c. Cu₂NiO(B₂O₅): a=3.2003(10), b=14.775(3), c=9.097(3), β=93.28(4), V=429.4(2) Å³, Z=4; and Cu₂MgO(B₂O₅): a=3.2401(6), b=14.790(2), c=9.147(2), β=94.88(2), V=436.7(2) Å³, Z=4. The structures of Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅) were, respectively, refined from 804 and 1000 independent reflections to the final residuals R1=0.0366, wR2=0.0911 and R1=0.0231, wR2=0.0644. Both compounds exhibit a chevron-like structure built up of ribbons, made of edge-connected copper and nickel-oxygen polyhedra, running along the (1 0 0) direction. These ribbons are connected from one another via oxygen atoms and the cohesion of the three-dimensional network is ensured by [B₂O₅] entities. Cu in part occupies the position for Ni or Mg, so that the compounds actually are solid solution compounds. Ni or Mg atoms are octahedrally coordinated by oxygen, while the two pure Cu sites show [4] and [4+1] coordination, for Cu(1) and Cu(2), respectively. The ELNES B-K edge spectra for the two compounds support that the borate group present is [B₂O₅].     

Synthesis and crystal structure of Sr10Al6O19: a derivative of the perovskite structure type in the system SrO-Al2O3

Sr₁₀Al₆O₁₉ is monoclinic, space group C12/c1, a=34.5823(21) Å, b=7.8460(6) Å, c=15.7485(9) Å, β=103.68(1)°, V=4151.9(7) Å³, Z=8. The structure has been solved from a single crystal diffraction dataset by direct methods and subsequently refined by a full-matrix least-squares process to a residual index of R(|F|)=0.038 for 2537 observed reflections with I>2σ(I). The compound is an oligoaluminate containing highly puckered [Al₆O₁₉]-groups of corner-sharing tetrahedra; it is the first purely aluminate cluster of this type, but it resembles the [□₆O₁₉]-group recently found in α-Sr₁₀□₆O₁₉. Linkage between the hexamers is provided by 11 crystallographically different strontium atoms located in planes parallel (1 0 0). They are coordinated by six-eight next oxygen neighbours. The structure can be derived from perovskite, ABO₃, by introducing ordered vacancies into the substructure of the oxygen atoms. The A-sites in Sr₁₀Al₆O₁₉ are exclusively occupied by Sr atoms, whereas strontium and aluminum atoms reside on the B-positions in the ratio 1:3. The relationship with perovskite can be expressed in the crystal chemical formula Sr(Al_3/4Sr_1/4)(O_19/8□_5/8).     

The crystal structure of lithium tantalum oxyfluoride LiTaO2F2

A structural analysis of lithium tantalum oxyfluoride LiTaO₂F₂ has been carried out by means of single-crystal diffraction methods. The symmetry is tetragonal, space group I4/mmm, with a cell having the dimensions : a = 3.903 ± 0.003, $\text{c}\text{= 25.380 ± 0.008}\text{A}\text{?}$ and containing five formula units. The structure was solved by Patterson and Fourier techniques and was refined by full-matrix least squares to an R value of 0.056. The structure consist of infinite ReO₃ type blocks three units-cells thick stacked perpendicularly to the c axis and shifted along the [110] direction with respect to each other. These blocks are connected together by the lithium atoms in a squarepyramidal coordination.     

SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.     

The crystal structure of Ni5TiB2O10

The crystal structure of Ni₅TiB₂O₁₀ was determined by single crystal X-ray analysis. The compound has the same structure as the mineral ludwigite. The orthorhombic celldimensions and space group are $\text{a}\text{=9.206(7)}\text{A}\text{?}$, $\text{b}\text{=12.224(9)}\text{A}\text{?}$, $\text{c}\text{=2.994(2)}\text{A}\text{?}$, Pbam z=2. Ti and Ni are disordered on one equipoint.     

The crystal structure of Pb8Bi2(PO4)6O2

Single crystals of Pb₈Bi₂(PO₄)₆O₂ were grown by the Czochralski technique, and the structure of this compound was determined. It was found to crystallize in Pnma orthorhombic symmetry with a = 13.313, b = 10.284 and $\text{c}\text{= 9.219}\text{A}\text{?}$. The structure was refined to an R value of 7%. Powder diffraction data are also reported.     

Cation ordering and high-temperature crystal structure of La2NiRuO6

The structure of La₂NiRuO₆ is studied with conventional X-ray and synchrotron-radiation diffraction methods. The obtained results show that this compound has a double perovskite structure with ordered arrangement of the B-site cations and P2₁/n space group. High-temperature diffraction measurements show that this structure is preserved up to 900 °C.     

Phase relations in the BaO-B2O3-TiO2 system and the crystal structure of BaTi(BO3)2

In this paper, the subsolidus phase relations in the ternary system BaO-B₂O₃-TiO₂ have been investigated. The phase diagram consists of 15 ternary phase regions. There exist 11 binary compounds and two ternary compounds. The ternary compound, BaTi(BO₃)₂, is isostructural with CaMg(CO₃)₂. It crystallizes in a rhombohedral system with the space group R-3. The lattice parameters are a=5.0205(2) and c=16.3844(1) Å. Final refinement on the diffraction data converge to R_p=9.09, R_wp=12.24, and R_exp=3.75%.     

Synthesis, crystal structure and infrared study of LiEr(PO3)4

A single-crystal X-ray diffraction analysis has been performed on LiEr(PO₃)₄ prepared by the flux method. The compound crystallizes in the monoclinic system with space group C2/c and cell parameters: a = 16.262(2), b = 7.032(1), c = 9.549(2) Å and β = 125.95(1)°. The crystal structure was refined based on 1272 independent reflections with I > 2σ(I). Final values of the reliability factors were improven considerably: R(F²) = 0.0180 and wR(F²) = 0.0490. The LiEr(PO₃)₄ structure is characterized by infinite chains (PO₃)_n, extending parallel to the b direction. The ErO₈ dodecahedra and LiO₄ tetrahedra alternate on two-fold axes in the middle of four (PO₃)_n chains. The vibrational study by infrared absorption spectroscopy is reported.     

Refinement of the crystal structure of HoRu2Si2 (ThCr2Si2-type)

The crystal structure of HoRu₂Si₂ has been determined from single crystal X-ray counter data obtained from a single crystal specimen which was prepared from an arc melted sample heat-treated at 500° C for 4 weeks and quenched. HoRu₂Si₂ is tetragonal with space group I4/mmm, and cell parameters a=4.1552(9) and $\text{c}\text{=9.5178(68)}\text{A}\text{?}$; Z = 2. The final reliability factor $\text{R}\text{=}\text{solΣΔ}\text{F}\text{|}\text{Σ|}\text{F}{}_{\mathrm{o}}\text{|}$ is 0.052 for 97 independent reflections; $\text{|}\text{F}{}_{\mathrm{o}}\text{| > 2 б}$. HoRu₂Si₂ is isotypic with the ordered structure type of ThCr₂Si₂ (BaAl₄-derivative type).     

Synthesis and crystal structure of a novel lithium bismuth phosphate, Li2Bi14.67(PO4)6O14

A lithium bismuth phosphate, Li₂Bi_14.67(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. Li₂Bi_14.67(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.