Zur Struktur von Ba3SmRu2O9, Ba3SmIrRuO9 und Ba2InIrO6

On the Structure of Ba₃SmRu₂O₉, Ba₃SmIrRuO₉, and Ba₂InIrO₆ The compounds Ba₃SmRu₂O₉, Ba₃SmIrRuO₉, and Ba₂InIrO₆ have a hexagonal BaTiO₃ structure (sequence (hcc)₂) with an ordered cationic distribution. The 6 L stacking polytypes Ba₃BM₂O₉ show an 1:2 order (M₂O₉ double octahedra and BO₆ single groups) and crystallize in the space group P6₃/mmc. The refined, intensity related R′ values are 6.9% (Ba₃SmRu₂O₉) and 6.5% (Ba₃SmIrRuO₉). The 1:1 ordered Ba₂InIrO₆, with InIrO₉ double groups and InO₆^?, IrO₆-single octahedra, belongs to the space group P3 m1; the refined R′ is 7,3%.     

Crystal growth of new perovskite and perovskite related iridates: Ba3LiIr2O9, Ba3NaIr2O9, and Ba3.44K1.56Ir2O10

Single crystals of Ba₃LiIr₂O₉, Ba₃NaIr₂O₉, and Ba_3.44K_1.56Ir₂O₁₀ were grown from hydroxide fluxes. Ba₃LiIr₂O₉ and Ba₃NaIr₂O₉ form in the 6H–BaTiO₃ or triple perovskite structure, which is derived from the hexagonal and cubic stacking of [AO₃] layers. The structure contains face-sharing Ir₂O₉ octahedra pairs, which are connected via corner shared LiO₆ (NaO₆) octahedra. Both compounds crystallize in the space group P6₃/mmc, Z=2, with a=5.7804(4) and c=14.302(1) and a=5.866(4) and c=14.596(1) for the Li and Na member, respectively. The structure of Ba_3.44K_1.56Ir₂O₁₀ is derived from the stacking of [AO₃] and mixed [A₂O] layers, and is an n=3 member of the [A_nM_n−1O_3n][A₂O] family of hexagonal perovskite related oxides. The structure of Ba_3.44K_1.56Ir₂O₁₀ consists of (Ba₃Ir₂O₉) slabs separated by [(Ba,K)₂O] layers and is isostructural with Ba₅Ru₂O₁₀. The (Ba₃Ir₂O₉) slabs contain isolated, face-sharing Ir₂O₉ octahedra pairs. The compound crystallizes in the space group P6₃/mmc, Z=2, with a=5.91330(1) Å and c=18.1792(7) Å. The magnetic moments determined from the temperature dependence of the magnetic susceptibility are low for all three oxides, which is thought to be due to a combination of spin–orbit coupling and strong exchange interactions within the iridium octahedra pairs.     

Photoluminescence of Ba3W2O9: Confirmation of a structural principle

The crystal structure of Ba₃W₂O₉ contains isolated W₂O^6?₉ groups. These are reported to luminesce efficiently. This shows that clusters of tungstate octahedra emit more efficiently than the isolated species.     

Low temperature structural phase transition of Ba3NaIr2O9

Single crystal X-ray and synchrotron X-ray powder diffraction have been used to probe the structure of Ba₃NaIr₂O₉ from 300 K down to 20 K. Ba₃NaIr₂O₉ is found to undergo a structural transition from hexagonal symmetry, P6₃/mmc, at ambient temperature to monoclinic symmetry, C2/c, at low temperature. The evolution of the unit cell volume upon cooling is indicative of a higher order structural transition, and the symmetry breaking becomes apparent as the temperature is decreased. The low temperature monoclinic structure of Ba₃NaIr₂O₉ contains strongly distorted [NaO₆] and [IrO₆] octahedra in comparison to the room temperature hexagonal structure.     

Die Kristallstrukturen der hexagonalen Elpasolithe Ba3NiSb2O9 und Ba3CuSb2O9 – röntgenographische und spektroskopische Ergebnisse

The Structures of the Hexagonal Elpasolite-Type Compounds Ba₃NiSb₂O₉ and Ba₃CuSb₂O₉ The results of an X-ray single crystal study of the hexagonal elpasolite Ba(NiSb₂)⁽⁶⁾O₉ are given. (Space group: C; a = b = 5.837 Å, c = 14.392 Å; Z = 2). The structure can be described by close-packed BaO₃ layers alternating in the sequence c c h c c h … (hex. BaTiO₃ type). Groups of two octahedra with common faces are connected by SbO₆ octahedra via common corners. They are occupied alternately by Ni and Sb. The final reliability index was R = 3.0%. The Cu²⁺-compound is of the same structural type. The ligand field and EPR spectra are discussed in comparison with related Ni²⁺ and Cu²⁺ compounds.     

Die Kristallstruktur der Hexagonalen Verbindungen BaMeIISbO9. II. Ba3CuSb2O9

Crystal Structure of the Hexagonal Compounds Ba^II₃Me^IISb^v₂O₉. II. Ba₃CuSb₂O₉ The crystal structure of the compound Ba₃CuSb₂O₉ was determined from single crystal X-ray diffraction data and refined down to R = 0.03. Ba₃CuSb₂O₉ crystallizes in the hexagonal space group P6₃mc (C) with a = b = 5.809 Å, C = 14.321 Å and Z = 2. The structure can be described by close–packed BaO₃ layers in the sequence cchcchcch…?(hex. BaTiO₃ type). Groups of two octahedra with common faces are connected by SbO₆ octahedra via common corners. They are occupied alternately by Cu and Sb. In agreement with the EPR spectra the CuO₆-octahedra present no static Jahn-Teller distortion at room temperature. However the thermal ellipsoids of the oxygen atoms indicate the presence of adynamic Jahn-Teller-effect.     

Ba2Ti2Si2O9F2, a new titanium silicate

Dibarium dititanium difluoride dioxide heptaoxidodisilicate, Ba₂Ti₂Si₂O₉F₂, is a new edge‐sharing titanate with a unique titanium silicate framework. All atoms in the structure are in general positions. Titanium oxyfluoride octahedra combine with silicon tetrahedra to form a double stacked chain, which is the base unit of the layered framework. The Ba atoms lie in channels that extend along the a axis.     

Ba3Lu4O9: Synthese und Strukturuntersuchung

Ba₃Lu₄O₉: Synthesis and Crystal Structure Determination Single crystals of Ba₃Lu₄O₉ were prepared by high temperature reactions (CO₂-Lasertechnique). The single crystal X-ray work leads to a rhombohedral symmetry with a = 8.96 Å and α = 39.42° (space group C—R3). Characteristic features of this crystal structure are shown and discussed.     

THERMAL DEHYDRATION OF BARIUM AND CALCIUM TRIMETAPHOSPHATE HEXAHYDRATES: Ba3(P3O9)26H2O AND Ca3(P3O9)26H2O

Abstract

Ba₃(P₃O₉)₂6H₂O and Ca₃(P₃O₉)₂6H₂O have mobile H₂O's which, under a dynamic vacuum of about 0.133 Pa, leave the lattice without disrupting it. Under water-vapor pressure, dehydration is accompanied by hydrolysis of P₃O₉ ^3- rings. The final product of dehydration is the β polyphosphate.     

Ein neuer Bautyp der Oxohalogenoferrate: Ba3 Fe2 O5 Cl2 und Ba3 Fe2 O5 Br2

New Structure Type of the Two Oxohalogenoferrites: Ba₃Fe₂O₅Cl₂ and Ba₃Fe₂O₅Br₂ The hitherto unknown compounds Ba₃Fe₂O₅Cl₂ (A) and Ba₃Fe₂O₅Br₂ (B) are pre-pared and examined by single crystal techniques. (A) and (B) crystallizes in the cubic space group I2₁ 3-T⁵; (A) a = 9.9705(3) and (B) a = 10.0039(8) Å, Z = 4. The new structure consists of 10 corner-shared tetrahedra which are connected to a two-dimensional ring system. The differences to the previously investigated compound Sr₃Fe₂O₅Cl₂ are discussed.     

Die neuen Schichtsilicate Ba3Si6O9N4 und Eu3Si6O9N4

The New Layer‐Silicates Ba₃Si₆O₉N₄ and Eu₃Si₆O₉N₄ The new oxonitridosilicate Ba₃Si₆O₉N₄ has been synthesized in a radiofrequency furnace starting from BaCO₃, amorphous SiO₂ and Si₃N₄. The reaction temperature was at about 1370 °C. The structure of the colorless compound has been determined by single‐crystal X‐ray diffraction analysis (Ba₃Si₆O₉N₄, space group P3 (no. 143), a = 724.9(1) pm, c = 678.4(2) pm, V = 308.69(9)· 10⁶ pm³, Z = 1, R1 = 0.0309, 1312 independent reflections, 68 refined parameters). The compound is built up of corner sharing SiO₂N₂ tetrahedra forming corrugated layers between which the Ba²⁺ ions are located. Substitution of barium by europium leads to the isotypic compound Eu₃Si₆O₉N₄. Because no single‐crystals could be obtained, a Rietveld refinement of the powder diffractogram was conducted for the structure refinement (Eu₃Si₆O₉N₄, space group P3 (no. 143), a = 711.49(1) pm, c = 656.64(2) pm, V = 287.866(8) ·10⁶ pm³, R_p = 0.0379, R_F² = 0.0638). The ²⁹Si MAS‐NMR spectrum of Ba₃Si₆O₉N₄ shows two resonances at ?64.1 and ?66.0 ppm confirming two different crystallographic Si sites.     

Über Ruthenium-Perowskite vom Typ Ba2BRuO6 und Ba3BRu2O9 mit B = Indium,Rhodium

On Ruthenium perovskites of type Ba₂BRuO₆ and Ba₃BRu₂O₉ with B = Indium, Rhodium The black perovskites Ba₂InRu⁵⁺O₆ and Ba₃InRu₂O₉ (mean oxydation state of ruthenium: +4.5) adopt the hexagonal BaTiO₃ structure and form a continuous series of mixed crystals. According to the intensity calculations and analysis of the vibrational spectroscopic data an ordered distribution between indium and ruthenium is present: 1:1 order in Ba₂InRuO₆ (space group P3 m1 ? D; R′ = 5.3%); 1:2 order in Ba₃InRu₂O₉ (space group P6₃/mmc ? D; R′ = 4.6%). The corresponding black Rh compounds, Ba₂RhRuO₆ and Ba₃RhRu₂O₉, crystallize in the rhombohedral 9 L type of BaRuO₃.     

Eu3+在Ba2TiSi2O8中的发光

红色荧光材料主要有(碱土)硫化物体系[1,2],(碱土)钛酸盐体系[3,4],氧化稀土体系[5],硅酸盐体系[6]以及其它氧化物体系如MO∶Eu~(3 )(M=Ca、Sr、Ba)[7],SrAl2O4∶Eu~(2 )[8]等。在这些体系中,主要以Eu3 做激活     

Zur Kristallstruktur von Ba3In2O6

About the Crystal Structure of Ba₃In₂O₆ Single crystals of Ba₃In₂O₆ could be prepared by recrystallization of a flux and by solid state reaction in closed platinium tubes, respectively. Ba₃In₂O₆ crystallizes with tetragonal symmetry (space group 14/mmm, a = 4.1868; c = 21.7041 Å, Z = 2). Single crystal X-ray work lead to a crystal structure like La_2-xSr_1+xCu₂O_6-δ therefor Ba₃In₂O₆ is a modified member of the Sr₃Ti₂O₇-Type. The coordinations of Ba²⁺ and In³⁺ are described and the relations to the Sr₃Ti₂O₇-type are discussed.     

Barium antimonide oxide,Ba3Sb2O

The antimonide oxide Ba₃Sb₂O consists of discrete [Sb₂]^4? and O^2? anions, and crystallizes with a new structure type. The Sb—Sb distances are comparable to those known from electron‐precise zintl phases and the tetrahedral coordination of the O^2? anion is also observed in some other Ba‐rich metallide oxides.     

Probing phase formation and structural ordering in Ba3ZnNb2O9 films using confocal Raman microscopy

In this paper we investigated the phase formation and structural ordering in spin-coated Ba₃ZnNb₂O₉ perovskite films using confocal Raman microscopy. The films were deposited through polyester resins obtained from a polymeric precursor. Initially, the films were characterized by X-ray diffraction and atomic force microscopy. Raman spectroscopy confirmed the crystalline structure of the main phase, as well as its partially disordered feature. Raman mappings were employed to probe the secondary phase distribution in the films, and to determine the calcining time-dependent film thicknesses.     

La取代Ba对Ba1-xLaxMn3Al9O19-α催化剂结构及甲烷催化燃烧性能的影响

采用以尿素水解为基础的水热合成法制备了La和Mn取代的六铝酸盐催化剂(Ba1-xLaxMn3Al9O19-α).在Mn含量达到阈值时,研究了不同量的La取代Ba对Ba1-xLaxMn3Al9O19-α的相组成、结构、热稳定性及甲烷催化燃烧活性的影响.当x≥0.4时,水热合成过程中生成的La2(CO3)3在530-580℃分解,800-900℃时与-γAl2O3反应生成LaAlO3钙钛矿相,可抑制由BaCO3分解而生成的Ba2+的固相扩散,从而阻止了BaAl2O4尖晶石相的生成,使Ba2+在固相中保持较高的分散性,促进了六铝酸盐(-βAl2O3)相的形成.当x<0.4时,BaAl2O4尖晶石相的存在引起催化剂比表面积和催化燃烧活性的降低.La3+取代Ba2+后,六铝酸盐结构发生一定程度的扭变.这种扭变越大,所形成的六铝酸盐催化剂的热稳定性越差.Ba1-xLaxMn3Al9O19-α催化剂的甲烷催化燃烧活性随x的增大而增加,x=0.8时催化剂的活性最佳.