ChemInform Abstract: Order—Disorder Transition Involving the A‐Site Cations in Ln3+Mn3V4O12 Perovskites.

LnMn₃V₄O₁₂ (Ln: La, Nd, Gd, Y, Lu) perovskites are prepared by solid state reactions of stoichiometric amounts of Ln₂O₃, Mn₂O₃, V₂O₃, and V₂O₅ (gold capsules, 9 GPa, 900 °C, 30 min).     

ChemInform Abstract: The Synthesis and Characterization of LaCa2Fe2GaO8.

The title compound is prepared from stoichiometric mixtures of La₂O₃, SrCO₃, Ga₂O₃, and Fe₂O₃ (flowing Ar, 1300 °C, 80 h) and characterized by neutron powder diffraction and magnetic measurements.     

ChemInform Abstract: Synthesis and Crystal Structure of a Novel Ludwigite Borate: Mg2InBO5.

The title compound is prepared by solid state reaction of a stoichiometric mixture of MgO, In₂O₃, and H₃BO₃ (1300 °C, 36 h).     

Zur Darstellung und Struktur von LaNb5O14

Preparation and Structure of LaNb₅O₁₄ Single crystals of LaNb₅O₁₄ could be prepared by chemical transport reactions (T₂ → T₁; T₂ = 1050°C; T₁ = 950°C) using chlorine as transport agent. LaNb₅O₁₄ crystallizes in the orthorhombic space group Pbem with cell dimensions a = 3.8749(2) Å; b = 12.4407(6) Å and c = 20.2051(9) Å; Z = 4; R = 6.28%, R_w = 3.74%. The structure consists of two types of Nb? O-polyhedra. Especially remarkable are chains of edge-sharing pentagonal NbO₇-bipyramids, which are interconnected by corner-sharing NbO₆-octahedra. Tunnels running in a-direction are created by this framework of NbO₆- and NbO₇-polyhedra. Lanthanum atoms are located in these tunnels at levels inbetween the niobium atoms. The relationship to O? LaTa₃O₉ and M? CeTa₃O₉ type structures will be discussed.     

ChemInform Abstract: YCa3(CrO)3(BO3)4: A Cr3+ Kagome Lattice Compound Showing No Magnetic Order Down to 2 K.

Polycrystalline gaudefroyite‐type YCa₃(CrO)₃(BO₃)₄ with Cr³⁺ ions (3d³, S = 3/2) forming an undistorted Kagome lattice is prepared by reaction of a stoichiometric mixture of Y₂O₃, CaCO₃, Cr₂O₃, H₃BO₃ in a KCl flux (Al₂O₃ crucible, 1000 °C, 1 d) followed by re‐grinding and further annealing (1000 °C, 2 d, 95% yield).     

Die Perthioborate RbBS3, TIBS3 und TI3B3S10

The Perthioborates RbBS₃, TIBS₃, and Tl₃B₃S₁₀ . RbBS₃ (P2₁/c, a=7.082(2) Å, b=11.863(4) Å, c=5.794(2) Å, β=106.54(2)°) was prepared as colourless, plate-shaped crystals by reaction of stoichiometric amounts of rubidium sulfide, boron, and sulfur at 600°C and subsequent annealing. TlBS₃ (P2₁/c, a=6.874(3) Å, b=11.739(3) Å, c=5.775(2) Å, β=113.08(2)°) which is isotypic with RbBS₃ was synthesized from a sample of the composition Tl₂S · 2 B₂S₃. The glassy product which was obtained after 7 h at 850°C was annealed in a two zone furnace for 400 h at 400→350°C. Yellow crystals of TlBS₃ formed at the warmer side of the furnace. Tl₃B₃S₁₀ (P1 , a=6.828(2) Å, b=7.713(2) Å, c=13.769(5) Å, α=104.32(2)°, β=94.03(3)°, γ=94.69(2)°) was prepared as yellow plates from stoichiometric amounts of thallium sulfide, boron, and sulfur at 850°C and subsequent annealing. All compounds contain tetrahedrally coordinated boron. The crystal structures consist of polymeric anion chains. In the case of RbBS₃ and TlBS₃ nonplanar five-membered B₂S₃ rings are spirocyclically connected via the boron atoms. To obtain the anionic structure of Tl₃B₃S₁₀ every third B₂S₃ ring of the polymeric chains of MBS₃ is to be substituted by a six-membered B(S₂)₂B ring.     

Crystal chemistry and phase equilibria of the CaO-½Eu2O3-CoOz system at 885 °C

The CaO-½Eu₂O₃-CoO_z system prepared at 885 °C in air consists of two calcium cobaltate compounds, namely, the 2D thermoelectric oxide solid solution, (Ca_3−xEu_x)Co₄O_9−z (0 ≤ x ≤ 0.5) which has a misfit layered structure, and the 1D Ca₃Co₂O₆ compound which consists of chains of alternating CoO₆ trigonal prisms and CoO₆ octahedra. Ca₃Co₂O₆ was found to be a point compound without the substitution of Eu on the Ca site when prepared at 885 °C. A solid solution region of distorted perovskite, (Eu_1−xCa_x)CoO_3−z (0 ≤ x ≤ 0.22, space group Pnma) was established. The (Eu_0.91(1)Ca_0.09(1))CoO_3−z perovskite member has a distorted structure with tilt angles θ (17.37°), ϕ (8.20°), and ω (19.16°) which represent rotations of an octahedron about the pseudo-cubic perovskite [110]_p, [001]_p and [111]_p axes. The reported Eu₂CoO₄ phase was not observed at 885 °C, but a ternary Ca-doped oxide, (Eu_1+xCa_1−x)CoO_4−z (Bmab) where 0 ≤ x ≤ 0.10 was found to be stable at this temperature. In the peripheral binary systems, Eu was not present in the Ca site of CaO, while a small solid solution region was identified for (Eu_1−xCa_x)O_(3−z)/2 (0 ≤ x ≤ 0.05). Seven solid solution tie-line regions and six three-phase regions were determined in the CaO-½Eu₂O₃-CoO_z system in air.     

Ln3UO6Cl3 (Ln=La,Pr, Nd) -. Die ersten Oxochlorouranate der Seltenen Erden

Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) — The First Oxochlorouranates of the Rare Earths . The new compounds Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were prepared by heating stoichiometric amounts of LnOCl/Ln₂O₃/U₃O₈ (7 : 1 : 1) (Ln=La, Nd) and PrOCl/Pr₆O₁₁/U₃O₈ (12 : 1 : 2) in silica ampoules (5 d, 1000°C, Ln=La; 9 d 800°C, Ln=Pr, Nd) in the presence of an excess of chlorine [p(Cl₂, 25°C)=1 atm]. Single crystals were obtained by chemical transport reactions using chlorine [p(Cl₂, 25°C)=1 atm] as transport agent [T₂=1000°C→T₁=900°C (Ln=La); T₂=840°C→T₁=780°C (Ln=Pr, Nd)]. Crystals of Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were investigated by X-ray diffraction methods and La₃UO₆Cl₃ additionally by high resolution electron microscopy. The compounds Ln₃UO₆Cl₃ crystallize in the hexagonal spacegroup P6₃/m (No. 176) with Z=2 formula units per unit cell. Isotypical structure refinements resulted in R=3.04% respectively R_w=1.91% (Ln=La), R=4.72% respectively R_w=3.80% (Ln=Pr) and R=3.99% respectively R_w=2.49% (Ln=Nd). Uranium is coordinated with six oxygen atoms forming a trigonal prism. Lanthanide ions are 10-coordinated (6 oxygen atoms, 4 chlorine atoms).     

ChemInform Abstract: Structural Phase Transitions in a New Compound Eu2AgGe3.

Eu₂AgGe₃ is prepared by high‐frequency induction melting of stoichiometric amounts of the elements (sealed Ta ampoules; 1.     

Beiträge zur Untersuchung anorganischer nichtstöchiometrischer Verbindungen. XLII. Darstellung und elektronenmikroskopische Untersuchung von α-MNb24O62 und MNb52O132 (M = Zr,Hf)

Contributions to the Investigation of Inorganic Non-Stoichiometric Compounds. XLII. Preparation and Electron Microscopic Investigation of α-MNb₂₄O₆₂ and MNb₅₂O₁₃₂ (M = Zr, Hf) The new ternary oxides α-HfNb₂₄O₆₂ and HfNb₅₂O₁₃₂ were obtained by oxidizing corresponding mixtures of HfO₂/NbO₂ and subsequent heating at 1150°C, a temperature which is unusually low for reactions in this system. In contrast, α-ZrNb₂₄O₆₂ could not be obtained in this way. Instead, samples with a certain amount of this compound were synthesized in a manner described previously, but they always contained considerable amounts of the β-Modification, too. HRTEM-investigations showed all compounds, mentioned above, to have block structures. The ideal structure of HfNb₅₂O₁₃₂ corresponds to the wellknown NbO_x?phase Nb₅₃O₁₃₂; α-ZrNb₂₄O₆₂ and α-HfNb₂₄O₆₂ are isostructural to Nb₂₅O₆₂. Additionally, there exist corresponding relationships to TiNb₅₂O₁₃₂ and TiNb₂₄O₆₂. Samples with a starting composition of ZrO₂/NbO₂ = 1:24 were microheterogenous and contained large amounts of the hybrid phase ZrNb₃₈O₉₇.     

ChemInform Abstract: Cobalt—Zinc Molybdates as New Blue Pigments Involving Co2+ in Distorted Trigonal Bipyramids and Octahedra.

Zn_1-xCo_xMoO₄ (x < 0.3) powders are prepared by solid state reaction of stoichiometric mixtures of MoO₃, Co₃O₄, and ZnO (alumina crucible, 700 °C, 20 h and 800 °C, 10 h).     

ChemInform Abstract: Rational Syntheses and Structural Characterization of Sulfur‐Rich Phosphorus Polysulfides: α‐P2S7 and β‐P2S7.

The polysulfides α‐ and β‐P₂S₇ are synthesized by heating stoichiometric mixtures of P₄S₃ and sulfur in the presence of catalytic amounts of anhydrous FeCl₃ as mineralizer (evacuated silica tube, 250 °C, 10 d).     

Synthesis and Structure of Europium Aluminium Garnet (EAG)

Europium aluminium garnet (Eu₃Al₅O₁₂, EAG) was synthesized by an aqueous sol‐gel process and subsequent thermal annealing at 800 – 850 °C. Eu₃Al₅O₁₂ crystallizes cubic ( and its crystal structure was refined from X‐ray powder data. The refined oxygen position in the structure of EAG yields four shorter and four longer distances between europium and the eight surrounding oxygen atoms, forming a distorted dodecahedron. Pure Eu₃Al₅O₁₂ can be treated at temperatures around 1000 °C before it converts into perovskite‐like EAP near 1300 °C.     

Photocurable silica hybrid organic–inorganic films for photonic applications

This paper reports the detailed preparation process of Eu²⁺ activated Sr₃Al₂O₆ by a sol-gel method in the reducing atmosphere. The effect of the calcining temperature on the microstructure, crystalline particle morphology and luminescence properties of Sr₃Al₂O₆:Eu²⁺ is systematically discussed. X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and fluorescence spectrophotometer were employed to characterize the phosphor. The Sr₃Al₂O₆:Eu²⁺ phosphor powders calcined at 1200 °C for 2 h possessed a Sr₃Al₂O₆ single cubic phase. The Sr₃Al₂O₆:Eu²⁺ crystallites showed flower-like morphology. The Sr₃Al₂O₆:Eu²⁺ phosphor powders exhibited a red broad emission band with emission peak at 612 nm under 472 nm excitation. Especially the Sr₃Al₂O₆:Eu²⁺ phosphor powders prepared at 1200 °C showed the strongest luminescence intensity, due to the pure phase and higher crystallinity of Sr₃Al₂O₆.     

Phase States of Europium Selenites in Aqueous Medium and in Thermal Analysis

The solubility isotherm of the system Eu₂O₃-SeO₂-H₂O was studied at 100°C. Certain amounts of the obtained selenites (normal and acid) were subjected to thermal analysis. The intermediate phases were isolated and chemical and X-ray phase analysis was made. The scheme of thermal decomposition was determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Die Oxidfluoride des Niobs und Tantals

Oxidefluorides of Niobium and Tantalum The reaction of NbF₅ with SiO₂ (silica glass ampules) at 310°C or with SiO₂ (Aerosil) at 180°C always leads to NbO₂F. To the contrary the reaction with laboratory glass (Jenaer Geräteglas) at 130°C leads to NbOF₃. TaF₅ reacts in silica glass ampules at 400°C by formation of TaO₂F, however at 300°C or 260°C by formation of TaOF₃. Silica glass did not react with NbF₅ at 130°C, however Nb₂O₅ and NbF₅ gave at 130°C in silica glass ampoules NbOF₃. Similarly, TaF₅ and Ta₂O₅ or TaO₂F formed at 260°C in nickel ampoules TaOF₃. The chemical and the thermochemical behaviour of oxidefluorides have been investigated. The compounds NbOF₃ and TaOF₃ are isomorphic. Lattice constants are mentioned.     

Eu4Bi3: Crystal Structure,Magnetic and Electronic Properties

The Eu? Bi system contains the phases Eu₅Bi₃, Eu₄Bi₃ and Eu₁₁Bi₁₀. The structure types of these phases have been determined by powder X-ray diffraction. Crystals of Eu₄Bi₃ (cubic, space group I4 3d; a = 9.920 Å, Z = 4, T = 130 K, R1/wR2 = 4.86/10.84%) were obtained in low yield by reaction of Eu, Mn, and Bi in the ratio 14:1:11 in a closed niobium tube (heating rate 30°C/h; reaction at 1050°C for 300 h, cooling rate 100°C/h). The crystal structure consists of distorted octahedra made up of six Bi coordinated to a central Eu atom. Eu is also coordinated to a three other Eu atoms and forms a three-dimensional network composed of interconnected rings. The Bi atoms are coordinated to eight Eu atoms. High yields of Eu₄Bi₃ can be prepared by reacting stoichiometric amount of the elements in a sealed tantalum tube at 1100°C for 24 h. Temperature dependent magnetic susceptibility is consistent with antiferromagnetic behavior with an ordering temperature of 18 K. The data could be fit with the Curie-Weiss law and a moment of 7.38 μ_B/Eu is obtained, consistent with all Eu atoms being Eu¹¹. Temperature dependent resistivity indicates that Eu₄Bi₃ is a metal with a room temperature resistance of 1.3 Ωcm.     

Zur Darstellung und Struktur neuer Niobate LnNb7O19 (Ln = La,Ce)

Preparation and Structure of LnNb₇O₁₉ (Ln = La, Ce) Two new ternary compounds, LaNb₇O₁₉ and CeNb₇O₁₉, could be prepared and characterized. At temperatures about 900°C already decomposition of both compounds will be initiated, but at lower temperatures (800°C) no reaction between the binary components occured. Single crystals could be obtained by chemical transport reactions (T₂ → T₁; T₂ = 800°C; T₁ = 780°C). Chlorine for mineralization or as transport agent is absolutely indispensable for preparation. Single crystal investigations on LaNb₇O₁₉ (R = 4.4%; R_w = 4.19%) result in the trigonal space group P3. The cell dimensions are a = 6.2531(2) A; c = 20.0685(10) Å; Z = 2. The structure can be described as to be build up by layers of 8-coordinated La and 6-coordinated Nb, alternating with layers of edge-sharing pentagonal NbO₇-bipyramids. Corresponding to the unusual sequence of layers the structure of LnNb₇O₁₉ (Ln = La,Ce) is the first example of a trigonal member of a family of structures, which has been described in detail by Jahnberg. The most examples are represented by tantalates, but only a few niobates related to these structures are known.     

Structure and magnetic susceptibility of MnNb3O6

The mixed valence state niobium compound MnNb₃O₆ was found while studying phase formations in the system MnO-Nb₂O₅-NbO. It is isostructural with A_xNb₃O₆, x ≤ 1 and A = Na, Ca. Single crystals were obtained by heating MnC₂O₄ · 2H₂O and Nb₂O₅ in a flow of H₂ at 1300 °C. Monophasic samples were also prepared by heating stoichiometric mixtures of MnO, Nb₂O₅ and Nb in niobium ampoules under Ar(g) at 1100 °C. The crystal structure of MnNb₃O₆ (Immm, Z = 4, a = 7.1057(5), b = 10.1420(6), c = 6.5341(5) Å) was refined, using singlecrystal MoKα X-ray diffraction data, to a weighted R value of 0.018 for 329 unique reflections. The structure contains undulating layers of NbO₆ octahedra of the type _α²[NbO_6/2]in the ac-plane, with the octahedra sharing edges along [001]and corners along [100]. Between the layers there are columns along [001]of edge-sharing square MnO₈ prisms alternating with columns containing Nb₂O₈ clusters with an Nb-Nb distance of 2.6163(5) Å. The magnetic susceptibility shows a Curie-Weiss behaviour: χ_M = C/(T+θ) with θ ≈ −22 K and μ_eff = 6.0(1) μ_B for T ≥ ca. 35 K, with a small deviation from this dependence at lower temperatures, indicating Mn²⁺ ions with localised magnetic moments and antiferromagnetic interactions.     

Two valence states in oxidized europium metal

Evaporated Eu films were exposed to oxygen up to 100 L. Using novel techniques of photoelectron spectroscopy in connection with synchrotron radiation as a tunable light source we detect the presence of both Eu²⁺ and Eu³⁺ ions in the sample with a close correspondence to mixed-valence Eu₃O₄. At elevated temperature (400°C) only Eu²⁺ is found.