Darstellung und elektronenmikroskopische Untersuchung neuer Verbindungen des Typs Ln3MO4Cl5 (Ln = La?Nd; M = Ge,V)

Preparation and Electronmicroscopic Investigation of New Compounds Ln₃MO₄Cl₅ (Ln = La? Nd; M = Ge, V) By heating mixtures of LnOCl, LnCl₃ und GeO₂ (2:1:1) in evacuated silica tubes (Pt-shells inside) the compounds Ln₃GeO₄Cl₅ (Ln = La? Nd) were prepared. The case that the temperature of preparation (La: T = 900°C, 8d; Ce: T = 800°C, 9d; Pr, Nd: T = 650°C, 13 d) had to be reduced from Ln = La to Ln = Nd indicates a decreasing thermodynamic stability in this direction. The compound La₃VO₄Cl₅ was prepared by heating (900°C, 8d) a mixture (2:1:1) of LaOCl, LaCl₃ and VO₂ and was investigated by electronmicroscopic techniques.     

Zwei neue Sulfidchloride der Lanthanide: Synthese und Kristallstruktur von Pr7S6Cl9 und Nd7S6Cl9

Two Novel Sulfide Chlorides of the Lanthanides: Synthesis and Crystal Structure of Pr₇S₆Cl₉ and Nd₇S₆Cl₉ The reactions of the elemental lanthanides (M = Pr and Nd, resp.) with sulfur and the respective trichlorides (MCl₃) in evacuated silica tubes (850 °C, 7 d) yield single-phase sulfide chlorides of the composition M₇S₆Cl₉ when appropriate molar ratios (4 : 6 : 3) of the reactants (M : S : MCl₃) are used. A slight excess of trichloride as a flux promotes the formation of lath-shaped transparent single crystals (Pr₇S₆Cl₉: pale green, Nd₇S₆Cl₉: pale violet) which prove to be water soluble and sensitive to hydrolysis. The crystal structure was determined from X-ray single-crystal data taking Nd₇S₆Cl₉ (monoclinic, P2/c (no. 13); a = 2425.0(9), b = 664.2(2), c = 691.8(2) pm, β = 97.43(3)°, Z = 2; R = 0.060, R_w = 0.048) as an example. According to Guinier powder data, Pr₇S₆Cl₉ crystallizes isotypically with a = 2441.6(9), b = 669.1(2), c = 696.3(2) pm, and β = 97.74(3)°. Thus four crystallographically independent cations (M³⁺) are present, each except for M2 coordinated by four S^2– but differing in the number of their next Cl^– neighbors. The figures of coordination are completed by four Cl^– about M1 (square antiprism, CN = 8) and by three Cl^– each about M3 and M4 (monocapped trigonal prisms, CN = 7, 2 Ç ). In contrast, M2 is coordinated by only two S^2– but five (plus one) Cl^– as bicapped trigonal prism (CN = 7 + 1). Eight crystallographically different anions, although indistinguishable by X-ray diffraction, exhibit coordination numbers of four (3 Ç S^2– and 1 Ç Cl^–) and three (4 Ç Cl^–) with respect to the cations. So PbO-analogous layers of the composition ²_∞{[(S6/7Cl_1/7)M_4/4]₇}⁸⁺ parallel (010) are formed, consisting of 6/7 of S^2– and only 1/7 of Cl^– as centering anions for the edge-shared (M³⁺)₄ tetrahedra for reasons of charge neutrality. These cationic layers are held together by alternatingly sheathed layers of Cl^– with only threefold coordinated anions.     

Weitere Oxochlorotitanate LnTiO3Cl der Seltenen Erden (LnSm?Lu) - Präparation,Kristallstruktur, elektronenmikroskopische Untersuchung

New Rare Earth Oxochlorotitanates LnTiO₃Cl (Ln?Sm? Lu) - Preparation, Structure and Electron Microscopic Investigations After the preparation of SmTiO₃Cl we made the attempt to prepare analogous compounds with the heavier rare earth elements. We present 2 methods to prepare powders of LnTiO₃Cl (Ln = Sm? Lu) together with a new method to prepare the rare earth oxychlorides LnOCl (Ln = Tm? Lu). There will be also presented 2 methods to get single crystals of these compounds via chemical vapour transport. The new rare earth oxochlorotitanates LnTiO₃Cl (Ln = Eu? Lu) are isotypic to SmTiO₃Cl. They crystallize in the monoclinic space group: C2/m (No. 12). The lattice parameters (Å) are between a = 9.716(3), b = 3.942(2), c = 10.100(4) (SmTiO₃Cl) and a = 9.748(1), b = 3.8454(5), c = 9.625(2) (LuTiO₃Cl), Z = 4. We observed a permanent decay of the cell volume with the decay of the radii of the cations. The structure of EuTiO₃Cl and DyTiO₃Cl was refined to R = 3.4% and R = 5.8% respectively. The crystal structure which has a certain similarity to brannerite can be described in a simplified way by saying that the rare earth and chlorine particles are located between walls of Ti? O-double-octahedra.     

Darstellung und Struktur von Ln3TiO4Cl5(Ln = La − Nd) - die ersten Oxochlorotitanate der Seltenen Erden

Preparation and Crystal Structure of Ln₃TiO₄Cl₅ (Ln = La?Nd) – the First Oxochlortitanates of Rare Earth The compounds Ln₃TiO₄Cl₅ have been prepared by reaction of LnCl₃/LnOCl/TiO₂ (1:2:1) (Ln = La?Nd) in evacuated silica ampoules. Single crystals of La₃TiO₄Cl₅ were obtained by chemical transport reaction (T₂ → T₁; T₂ = 1050°C, T₁ = 950°C) using chlorine (p(Cl₂; 298 K) = 1 atm) and sulfur as transport agents with La₂TiO₅ as starting material. La₃TiO₄Cl₅ crystallizes in the orthorhombic space group Pnma (No. 62) with cell-dimensions a = 16.760(2) Å, b = 4.0991(6) Å, c = 14.634(2) Å, Z = 4. The structure was refined to give R = 4.76%, R_w = 2.47%. Main building units are TiO₅ trigonal bipyramides and threefold capped trigonal prisms around La. The relationship to La₂TaO₄Cl₃ will be discussed.     

La0.5>RE0.3Sr0.2FeO3－δ (RE = Nd、Ce、Sm)体系双稀土阴极材料的制备与电性能

采用甘氨酸-硝酸盐法(GNP)合成了La0.5RE0.3Sr0.2FeO3－δ(RE=Nd、Ce、Sm)系列复合氧化物粉体. 用X射线衍射(XRD)和TG-DSC分析了样品钙钛矿物相的形成过程, 用Archimedes排水法测量体积密度并计算烧结样品的相对密度, 用四端子技术测量电导率. 结果显示, 掺Nd的样品1200 ℃烧结2 h成为单一立方钙钛矿结构, 掺Ce样品有明显的CeO2立方相析出, 掺Sm样品主相为钙钛矿结构伴有微弱的杂峰. 1250 ℃烧结2 h的La0.5Nd0.3Sr0.2FeO3－δ在600 ℃时电导率高达100 S•cm-1以上, 明显高于La0.5Ce0.3Sr0.2FeO3－δ及La0.5Sm0.3Sr0.2FeO3－δ样品的电导率, 预示着La0.5Nd0.3Sr0.2FeO3－δ可能是一种良好的中温固体氧化物燃料电池(SOFC)阴极材料.     

Neue thermische Abbauprodukte von Ln2CeMO6Cl3 (M = Nb,Ta; Ln = La–Sm) – Darstellung von strukturverwandtem (La, Tb)3,5TaO6Cl4–x

Contributions on the Investigation of Inorganic Nonstoichiometric Compounds. XLV. New Thermal Decomposition Products of Ln₂CeMO₆Cl₃ – Preparation of Structure‐related (La, Tb)_3.5TaO₆Cl_4–x The thermal decomposition (T £ 900–1050°C) of Ln₂CeMO₆Cl₃ (M = Nb, Ta; Ln = La, Ce, Pr, Nd, Sm) leads to the formation of two mixed‐valenced phases (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (phase ‘‘BB”︁”︁) and to the formation of chlorine according to redox‐reactions between Ce⁴⁺ and Cl^–. Single crystals of both phases (Ln, Ce)_3.25MO₆Cl_3.5–x (‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (‘‘BB”︁”︁) were obtained by chemical transport reactions using both powder of Ln₂CeMO₆Cl₃ (phase ‘‘A”︁”︁) and powder of (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) as starting materials and chlorine (p{Cl₂; 298 K} = 1 atm) or HCl (p{HCl; 298 K} = 1 atm) as transport agent. A crystal of (La, Ce)_3.25NbO₆Cl_3.5–x (”︁AB”︁”︁) (space group: C2/m, a = 35.288(1) Å, b = 5.418(5) Å, c = 9.522(1) Å, β = 98.95(7)°, Z = 4) was investigated by x‐ray diffraction methods, a crystal of (Pr, Ce)_3.5NbO₆Cl_4–x (”︁BB”︁”︁) was investigated by synchrotron radiation (λ = 0.56 Å) diffraction methods. The lattice constants are a = 18.863(6) Å, b = 5.454(5) Å, c = 9.527(6) Å, β = 102.44(3)° and Z = 4. Structure determination in the space group C2/m (No. 12) let to R1 = 0.0313. Main building units are NbO₆‐polyhedra with slightly distorted trigonally prismatic environment for Nb and chains of face‐sharing Cl₆‐octahedra along [010]. The rare earth ions are coordinated by chlorine and oxygen atoms. These main structure features confirmed the expected relation to the starting material Ln₂CeMO₆Cl₃ (phase ”︁A”︁”︁) and to (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ”︁AB”︁”︁).     

Gd4I6CN: Ein Carbidnitrid mit Ketten aus Gd6(C2)-Oktaedern und Gd6N2-Tetraederdoppeln

Gd₄I₆CN: A Carbide Nitride with Chains of Gd₆(C₂) Octahedra and Gd₆N₂ Double Tetrahedra The compound α-Gd₄I₆CN is prepared by reaction of Gd, GdI₃, C, and GdN (1:2:1:1 mole ratio) at 1 170 K in sealed Ta tubes. It is obtained as brown red, transparent needles which are air and moisture sensitive. The structure of α-Gd₄I₆CN contains Gd₆ octahedra centered by C₂ groups and double tetrahedra centered by N atoms. The units are alternatingly connected via common edges to form chains (Gd₂Gd_4/2C₂) (Gd_2/2Gd_2/2N)₂ parallel [001]. The linear chains are surrounded by I atoms above all free edges of the metal polyhedra and linked according to (Gd₂Gd_4/2C₂) (Gd₂Gd_4/2N₂)I_4/2I₈I₂ in the a – b plane. We also found β-Gd₄I₆CN, which is formed in a monotropic transition from the α-form. In the structure the chains of Gd octahedra and tetrahedra as described for α-Gd₄I₆CN are more densely packed. The structure of Y₆I₉C₂N is composed by chains of pairs of Y-octahedra and Y-tetrahedra, respectively. The octahedra are centered by C₂ groups, the tetrahedra by N-atoms. We also synthesized the compounds Gd₄Br₆CN und La₄I₆CN by tempering at 1 220 K. They are isotypic with α-Gd₄I₆CN.