The Crystal Structure of Ba2Cu2AlF11: a New Structure Type in Copper Fluoride Crystal Chemistry

Ba₂Cu₂AlF₁₁ is trigonal: a = 7.301(1) Å, c = 14.145(2) Å, γ = 120°, Z = 3. The crystal structure was solved in the space group P3₂ (n° 145), from X-ray single crystal data using 2675 unique reflections (2476 with F/σ(F) > 4). It consists in a complex tridimensional arrangement of copper-fluorine and aluminium-fluorine octahedra, with an original kind of linkage which involves simultaneously edges and vertices.     

The Crystal Structure of Ba2CuAlF9: a New Structure Type in Copper Fluoride Chemistry

Ba₂CuAlF₉ is monoclinic: a = 5.374(2) Å, b = 7.312(2) Å, c = 9.371(3) Å, β = 90.20(1)°, Z = 2, space group P2₁/c (n° 14). The crystal structure was solved from X-ray single crystal data using 1071 unique reflections (900 with F_o/σ(F_o) > 4, R factor = 0.075). It is built up from infinite isolated cis chains of [MF₆] mixed occupied fluorine octahedra sharing each, one edge and one vertex (M is randomly Cu or Al). An analogous kind of linkage was already observed for two other compounds from the ternary system BaF₂/CuF₂/AlF₃. Close structural relationships exist between the cationic subnetworks of γ-BaAlF₅ and Ba₂CuAlF₉.     

The Ternary System BaF2/CuF2/AlF3 and the Crystal Structure of Ba45Cu28Al17F197

The ternary system BaF₂/CuF₂/AlF₃ is investigated by X‐ray diffraction techniques and an isothermal section at 620 °C is established. It exhibits ten quaternary phases and among them Ba₄₅Cu₂₈Al₁₇F₁₉₇. This fluoride has a triclinic cell: a = 14.024(1) Å, b = 23.778(1) Å, c = 25.480(1) Å, α = 90.44(1)°, β = 90.26(1)°, γ = 107.03(1)°, Z = 2. Its crystal structure was solved in the space group P1 (n^o1), from X‐ray single crystal data using 41976 unique reflections. It is built up from a complex arrangement of aluminium and copper fluorine polyhedra, which are regular [AlF₆] and strongly distorted [CuF₆] octahedra, [CuF₆] trigonal prisms and [Cu₂F₁₀] bipolyhedral units constituted either by two octahedra, or one octahedron and one trigonal prism, connected by an edge. These polyhedra are organized in planes of about two octahedra thickness, which form a succession of sheets running perpendicularly to the [100] direction of the cell. Each sheet is constituted by infinite chains of distorted polyhedra connected by edges and vertices and linked together by the vertices of blocks of four and six polyhedra, involving aluminium fluorine octahedra and copper fluorine bipolyhedral units or octahedra. The barium ions, 10 to 14‐coordinated to fluorine atoms, ensure the electroneutrality of the structure. They are inserted inside the planes.     

Einbau von Al3+ in Ir3O12-Oktaedertripel in Ba4Ir2AlO10

Incorporation of Al³⁺ in Ir₃O₁₂ Octahedra-Triple in Ba₄Ir₂AlO₁₀ Single crystals of Ba₄Ir₂AlO₁₀ were prepared by solid state/flux reactions. It crystallizes with orthorhombic symmetry: space group D–Cmca; a = 5.778; b = 13.352; c = 13.084 Å; Z = 4. The structure is characterized by face connection of three IrO₆- or Ir/AlO₆-octahedra. X-ray investigations show an ordered occupation of the centric octahedron by Ir and a statistically distribution of Ir and Al in the adjacent octahedra. Calculations of the coulomb term of the lattice energy support a charge distribution in the manner Ir⁵⁺/Al³⁺? Ir⁴⁺? Ir⁵⁺/Al³⁺.     

Preparation and Crystal Structure of the Strontium Aluminium Fluoride Sr5Al2F16

Single crystals of Sr₅Al₂F₁₆ crystallize in colourless translucent plates and have been prepared by solid state synthesis, starting from stoichiometric mixtures of the binary fluorides. The crystal structure has been determined and refined from single crystal diffractometer data (orthorhombic, space group Ccca (no. 68), a = 7.4488(4) Å, b = 12.4714(7) Å, c = 14.1411(8) Å, V = 1313.67(13) ų, Z = 4, R[F ² > 2σ(F ²)] = 0.025; wR2(F ² all) = 0.056, 971 structure factors, 56 parameters) and can be derived from a slightly distorted c.c.p. arrangement where 7/8 of the c.c.p. positions are occupied by the metal atoms. The main features of the structure are AlF₆ octahedra and SrF₈ polyhedra with mean distances d(Al–F) = 1.791 Å and d(Sr–F) = 2.531 Å, respectively.     

Activity Enhancement of Pt/Ba/Al2O3 Mixed with Mn/Ba/Al2O3 for NOx Storage-reduction by Hydrogen

The storage and reduction of nitrogen oxides has attracted much attention as an efficient way to reduce NOx emission of lean-burn gasoline and diesel engines1-5. At present, NOx storage and reduction (NSR) catalysts based on Pt and Ba have been extensivel…     

The Crystal Structure of Ba58Ga22F180O

The crystal structure of Ba₅₈Ga₂₂F₁₈₀O is established by means of X‐ray single crystal diffraction. It is tetragonal: a = 22.033(1) Å, c = 17.626(1) Å, Z = 2. The structure is solved in the space group I4/mmm (n° 139), using 3219 independent reflections. It is mainly built from a deficient arrangement of fluorite‐type [FBa₄] tetrahedra connected by edges and vertices which constitutes the skeleton of the structure, giving rise to large cavities in which lie isolated fluorine ions in tetrahedral and octahedral barium environment, isolated [F₂Ba₆] bitetrahedra, isolated barium ions in eight‐coordination of fluorine and a complex arrangement of isolated [GaF₆] octahedra and isolated [Ga₂F₁₀O] bioctahedra.     

The Crystal Structure of ζ2‐Al3Cu4‐δ

The crystal structure of the ζ₂‐phase Al₃Cu_4‐δ was determined by means of X‐ray powder diffraction: a = 409.72(1) pm, b = 703.13(2) pm, c = 997.93(3) pm, space group Imm2, Pearson symbol oI24‐3.5, R_I = 0.0696. ζ₂‐Al₃Cu_4‐δ forms a distinctive a × √3a × 2c superstructure of a metal deficient Ni₂In‐type‐related structure. The phase is meta‐stable at ambient temperature. Between 400 °C and 450 °C it decomposes into ζ₁‐Al₃Cu₄ and η₂‐AlCu. Entropic contributions to the stability of ζ₂‐Al₃Cu_4‐δ are reflected in three statistically or partially occupied sites.     

Crystal Structure Determination of Tetrabarium‐digalliumoxide,Ba4Ga2O7

Single crystals of a new barium oxogallate were obtained by growth from a melt at 1500 °C. The compound is monoclinic, with cell parameters a = 17.7447(10) Å, b = 10.6719(5) Å, c = 7.2828(5) Å, β = 98.962(7)°, V = 1362.3(2) ų. The diffraction pattern shows systematic absences corresponding to the space group P12₁/c1. The structure was solved by direct methods followed by Fourier syntheses, and refined using a single crystal diffraction data set (R1 = 0.032 for 2173 reflections with I > 2σ(I)). The chemical composition derived from structure solution is Ba₄Ga₂O₇, with a unit cell content of Z = 6. Main building units of the structure are GaO₄ tetrahedra sharing one oxygen atom to form Ga₂O₇ groups. The Ga–O–Ga bridging angle of one of the two symmetrically independent groups is linear by symmetry. The dimers are crosslinked by barium cations coordinated by six to eight oxygen ligands.     

Ein neuer Strukturtyp mit flächenverknüpften BaO6-Oktaedern: Ba6Nd2Al4O15

Summary A compound Ba₆Nd₂Al₄O₁₅ with a new structure-type was prepared by solid state reaction. It crystallizes with hexagonal symmetry, space group C _6v ⁴ – P 6₃mc;a=11.5696;c=6.9662 Å;z=2. Ba₆Nd₂Al₄O₁₅ has a dominating Ba/O-framework with incorporated AlO₆-octahedra and AlO₄-tetrahedra. A main feature of the structure are face connected BaO₆-octahedra. One of the point positions of the heavy atoms is occupied statistically by Ba²⁺ and Nd³⁺.

     

Synthesis and Structure of Ba[ZrN2] and Ba2[NbN3]

Ba₃N₂ reacts at 950°C under pure N₂ with Zr to yield dark red, air-sensitive Ba[ZrN₂]. This new compound crystallizes in the tetragonal space group P4/nmm with a = 416.10(2), c = 839.2(1) pm and Z = 2. The crystal structure was solved and refined using X-ray and neutron powder diffraction data. In the nitrido zirconate [ZrN₂]^2? the Zr atoms exhibit a square-pyramidal coordination by five N atoms at distances of 201(3) and 220.2(2) pm. The pyramids share all the edges in the basal plane to form layers parallel to (001) with their apices alternately pointing up and down. The Ba²⁺ cations are integrated into these layers at the levels of the pyramidal apices. The structure can be interpreted as a stuffed PbFCl type. Ba₂[NbN₃] is formed by the reaction of Ba₃N₂ and NbN or of Ba and Nb at 1 000°C under N₂. Isostructural to Ba₂[TaN₃] it crystallizes in the monoclinic space group C2/c with a = 613.2(3), b = 1 176.8(3), c = 1 322.9(4) pm, β = 91.65(2)°, Z = 8. The nitrido niobate anions form chains of corner sharing NbN₄ tetrahedra with distances Nb? N between 188(1) and 199.9(9) pm.     

La0.5R0.5Ba2Cu3O7,Pr0.5R0.5Ba2Cu3O7以及RBa2Cu3o7（R=稀土）的键共价性计

使用复杂晶体化学键理论计算了Ｌａ０．５Ｒ０．５Ｂａ２Ｃｕ３Ｏ７（Ｒ＝Ｐｒ,Ｎｄ,Ｓｍ,Ｅｕ,Ｇｄ,Ｄｙ,Ｙ,Ｈｏ,Ｅｒ,Ｔｍ,Ｙｂ,Ｌｕ）（Ｌａ－Ｒ１２３）,Ｐｒ０．５Ｒ０．５Ｂａ２Ｃｕ３Ｏ７（Ｒ＝Ｌａ,Ｎｄ,Ｓｍ,Ｅｕ,Ｇｄ,Ｄｙ,Ｈｏ,Ｙ,Ｅｒ,Ｔｍ,Ｙｂ,Ｌｕ）（Ｐｒ－Ｒ１２３）以及ＲＢａ２Ｃｕ３Ｏ７（Ｒ＝Ｌａ,Ｐｒ,Ｎｄ,Ｓｍ,Ｅｕ,Ｇｄ,Ｄｙ,Ｈｏ,Ｙ,Ｅｒ,Ｔｍ）（Ｒ１２３）中Ｃｕ－Ｏ键的键共价性,结果表明Ｐｒ－Ｒ１２３,Ｌａ－Ｒ１２３,以及Ｒ１２３都应具有超导性,而实验结果是Ｌａ０．５Ｐｒ０．５Ｂａ２Ｃｕ０７,Ｒ０．５,Ｐｒ０．５Ｂａ２Ｃｕ３Ｏ７（Ｒ＝Ｌａ,Ｎｄ,Ｓｍ,Ｅｕ,Ｇｄ）无超导性,产生这种矛盾的原因尚不明确,需要做进一步的研究。     

ChemInform Abstract: Crystal Structure of Ba5In2Al2ZrO13.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Cadmium in tetragonal pyramidaler Koordination im Barium-Cadmium-Oxovanadat: Ba2Cd3(VO4)2(V2O7)

Cadmium in Square Pyramids of Oxygen in the Barium Cadmium Oxovanadate: Ba₂Cd₃(VO₄)₂(V₂O₇) Single crystals of Ba₂Cd₃(VO₄)₂(V₂O₇) have been prepared by crystallization of a melt of BaCO₃, CdO and V₂O₅. It shows orthorhombic symmetry, space group D? P2₁2₁2₁, a = 7.206(2), b = 9.978(1), c = 19.617(3) Å, Z = 4. The crystal structure is characterized by (VO₄)^3? and (V₂O₇)^4? groups, CdO₆ octahedra, BaO₁₂ and BaO₉ polyhedra and with respect to Cd containing oxides unusual square pyramids of O^2? around Cd²⁺. The observed [CdO₄] zickzack chains are connected by VO₄ tetrahedra, V₂O₇ double tetrahedra and CdO₅ pyramids, forming a tunnel structure along [100]. The tunnels are filled by barium.     

Pb3Fe2F12: A new fluorometallate with a tetrameric structural unit

Pb₃Fe₂F₁₂ grown by hydrothermal synthesis, crystallizes in the triclinic system, space group P1 , with a = 7.403(2) Å, b = 7.621(2) Å, c = 9.890(3) Å, α = 110.45(2)°, β = 107.98(1)°, γ = 95.92(2)°, V = 483.12(4) ų, Z = 2. The structure was solved from single crystal data using 3 913 independent reflections (R = 0.045 and R_w = 0.045). Characteristical of this structure is the presence of isolated tetrameric groups [Fe₄F₂₀]^8? in form of “rings” as previously observed in Ba₃Al₂F₁₂. “Independent” fluorine ions are also located and their cationic coordination is discussed. In contrast to Ba₃Fe₂F₁₂, all the rings are parallel in the structure.     

Tl2Ba2Ca2Cu3O10的化学键性质和同质异能位移研究

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n+4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu(1)-O bond is 0.561, and the average covalency of Cu(2)-O is 0.296. M(o)ssbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu (1) site in forms of Fe3+ and Fe4+; for higher doping, Fe3+ and Fe4+ ion occupies Cu(1) and Cu(2) site respectively.The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by M(o)ssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.     

Synthesis,Crystal Structure and Nonlinear Optical Properties of a new cluster compound: MoS4Cu3(PyPPh2)3Cl

Reaction of [NH₄]₂[MoS₄], CuCl and PyPPh₂ in the solid state produces a cube-like cluster. The cluster crystallizes in the orthorhombic space group P2₁2₁2₁ with four formula units in a cell of dimensions a = 12.8980(10) , b = 17.6820(10), c = 22.665(2) Å. Anisotropic refinement for all nonhydrogen atoms yielded the values R = 0.0397 and R _w = 0.1185 for 8803 observed reflections. The structure is built up from three [Cu(Ph₂PPy)]⁺ units bridged by MoS^2? ₄ to form a tetranuclear symmetrical cube-like molecule. Investigation of the third-order optical nonlinear value showed that it exhibits a considerable nonlinear absorptive and self-defocusing effect with α₂ = 1.3 × 10^?11 m w^?1 and n ₂ = ? 3.2 × 10^?18 m² w^?1 in a 1.5 × 10^?4 M DMF solution.     

Preparation of Y2Ba4Cu7O15-δ Superconductor without High Oxygen Pressure

The synthesis of bulk Y₂Ba₄Cu₇O_15-δ superconductor at atmospheric oxygen pressure via solid state sintering is reported. Temperature ranging from 860 to 890 °C as well as time interval over 2 to 15 days were used to investigate the formation of the Y₂Ba₄Cu₇O_15-δ phase. A time-temperature profile characterizing the conditions for the preparation of Y₂Ba₄Cu₇O_15-δ phase suggests the optimal condition to be sintering at 890 °C for over 10 days. Detailed results of X-ray diffraction, electrical resistivity, iodometric titration and magnetization measurements are described.     

(Ba6O)(ReN3)2: Synthesis,Crystal Structure and Physical Properties

The reaction of a mixture of barium and rhenium (3:1) at 850 °C under flowing nitrogen yielded the nitride‐oxide (Ba₆O)(ReN₃)₂ (R (No. 148); a = 8.1178(2) Å, c = 17.5651(4) Å; V = 1002.43(5) Å³; Z = 6). According to a structure refinement on X‐ray powder diffraction data, this compound is isostructural to a recently described nitride‐oxide of osmium of analogous composition. The structure consists of sheets of trigonal ReN₃ units and trigonal antiprismatic Ba₆O groups. The Ba–O distance of 2.73 Å is close to the sum of the respective ionic radii. The trigonal ReN₃^5– nitride anion displays a Re–N bond length of 1.94 Å, and is planar within the limits of experimental error. The constitution of the anion was confirmed by IR and Raman spectroscopy. The nitride‐oxide is stable up to 1000 °C, semiconducting (σ = 4.57 × 10^–3 Ω^–1 · cm^–1 at RT), and paramagnetic down to 25 K. A Curie–Weiss analysis resulted in a magnetic moment of μ = 0.68 μ_B per rhenium atom.