Über geordnete Perowskite mit Kationenfehlstellen. X. Verbindungen vom Typ ABB□1/4MVIO6 ≙ ABIIB□MO24 mit AII,BII = Ba,Sr, Ca und MVI = U,W

On Ordered Perovskites with Cationic Vacancies. X. Compounds of Type A B B □_1/4M^VIO₆ ? A B^IIB □M O₂₄ with A^II, B^II = Ba, Sr, Ca and M^VI = U, W Perovskites of type Ba₈B^IIB₂^III□UO₂₄ show polymorphic phase transformations of order disorder type. An 1:1 ordered orthorhombic HT form is transformed into a higher ordered LT modification with a fourfold cell content (four formula units Ba₈B^IIB□U₄O₂₄), compared to cubic 1:1 ordered perovskites A₂BMO₆. In the series Ba₈BaB□W₄O₂₄ and Sr₈SrB□W₄O₂₄ different ordering phenomena are observed. In comparison with 1:1 ordered cubic perovskites A₂BMO₆, the cell contains eight formula units AB^IIB□W₄O₂₄. The higher ordered cells with U^VI and W^VI are face centered, which has its origin in an ordering of cationic vacancies.     

Die Photolumineszenz der dreiwertigen Seltenen Erden in den Perowskitstapelvarianten Ba2La2−xSE MgW2□O12, Ba6Y2−xSEW3□O18 und Sr8SrGd2−x SEW4□O24

Photoluminescence of Trivalent Rare Earths in Perovskite Stacking Polytypes Ba₂La_2?x RE MgW₂□O₁₂, Ba₆Y_2?x RE W₃□O₁₈, and Sr₈SrGd_2?xRE W₄□O₂₄ Rhombohedral 12 L stacking polytypes Ba₂La_2?xREMgW₂□O₁₂ show with RE³⁺ = Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm; the 18 L stacking polytypes Ba₆Y_2?xREW₃□O₁₈ and the polymorphic perovskites Sr₈SrGd_2?xREW₄□O₂₄ with RE³⁺ = Sm, Eu, Dy, Ho, Er visible photoluminescence. The concentration dependence and the influence of the coordination number of the rare earth are reported.     

Interactions Magnetiques dans quelques Ferrites Oxyfluores a Structure Spinelle de Formule ZnxMFe2−xO4–xFx (M ? Fe,Co, Ni)

Magnetic interactions in some oxyfluoroferrites of spinel structure with the formula Zn_xMe_2?xO_4?xFx (M = Fe, Co, Ni) Whereas the ferromagnetic spin arrangement of the B-cations is not modified by the Zn²⁺?Fe³⁺ substitution in the ZnFe[Fe₂₊Fe³⁺]O_4?xF_x (0 ≤ x ≤ 0,50) spinel, this same substitution leads to a spin canting in the ZnFe[Co₂₊Fe³⁺]O_4?xF_x and ZnFe[Ni₂₊Fe³⁺]O_4?xF_x (0 ≤ x ≤ 0,80) simples. The difference in the magnetic behaviors with regard to the AB and BB interactions can be explained on the basis of the magnetic exchange theory.     

Strukturbestimmungen an geordneten Perowskiten des Typs Ba2BMVIO6

Determination of Structures of Ordered Perovskites of the Ba₂B M^VIO₆ Type Intensity calculations on powder patterns of Ba₂Y□_0.33M^VIO₆ with M^VI = U, W, Te und Ba₂Gd_0.67□_0.33UO₆ lead for the space group Fm3m/O with 8 Ba in 8c, 8/3 B^III and 4/3 □ in 4b, 4 M^VI in 4a and 24 O in 24e to R values between 4.3 and 7.6%. Two further models are discussed.     

Zur Kristallchemie von Ba3In2Zn5O11. Ein tOxoindat/zinkatsol;zinkat mit Zn10O20- und In4O16-Makropolyedern und erstmals O2− in tetraedrischer Koordination durch Zn2+

On the Crystal Structure of Ba₃In₂Zn₅O₁₁. An Oxoindate/zincatesol;zincate with Zn₁₀O₂₀ and In₄O₁₆ Macropolyhedra with Zn²⁺ in Tetrahedral Coordination by O^2? Ba₃In₂Zn₅O₁₁ was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T-F4 3m, a = 13.3588 Å, Z = 8. Zn²⁺ show tetrahedral coordination by O^2?, forming Zn₁₀O₂₀ macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn₁₀O₂₀ parts. Edge connection of four InO₆ octahedra results in In₄O₁₆ groups. The crystal structure will be shown and discussed.     

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.     

Über Verbindungen des Typs Ba2BIIIOsVO6

Compounds of Type Ba₂B^IIIOs^VO₆ The black perovskites of type Ba₂B^IIIOs^VO₆ crystallize cubic (B^III ? Pr, Nd, Sm—Lu, Y) and rhombohedral (B^III ? La) respectively; the cell volumina decrease linearily with (r_BIII)³. Intensity calculations on powder data for Ba₂YOsO₆ (space group Fm3m—O) and Ba₂LaOsO₆ (space group R3m—D) gave the intensity related R′ values of 4.6% and 5.0% respectively. The results of the vibrational spectroscopic investigations are reported in common with the bond orders, M? O distances and mean amplitudes and compared with the corresponding values of the series Ba₂B^IIIIr^VO₆ and Ba₂B^IIIRu^VO₆.     

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.     

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.     

Zur Kenntnis eines Oxoargentato(I)-aurats(III): Ba4AgAuO6

On the Oxoargentato(I)-aurat(III): Ba₄AgAuO₆ The hitherto unknown compound Ba₄AgAuO₆ was prepared by oxidizing Ba/Au/Ag alloy with BaO₂/Ba(OH)₂ mixture in closed Ag tubes. X-ray single crystal investigation led to orthorhombic symmetry space group D-Cmcm; a = 13.275; b = 5.782; c = 11.396 Å; Z = 4. Ba₄AgAuO₆ shows distorted pentagonal bipyramidal polyhedra around Ba²⁺ and square planar AuO₄ polygones. Ag⁺ shows an unusual 2 + 2 coordination by O^2?.     

Zur Kenntnis von Ba6La2Co4O15

About Ba₆La₂Co₄O₁₅ Ba₆La₂Co₄O₁₅ were prepared and investigated by X-ray single crystal work. It crystallizes with hexagonal symmetry, space group C–P6₃mc; a = 11.8082; c = 7.0019 Å; Z = 2. Ba²⁺ show face connected BaO₆-octahedra and larger polyhedra of C.N. = 10 and 12. Co³⁺ is surrounded by four and six (tetrahedra, octahedra) oxygen. The Ba²⁺ and La³⁺ ions occupy one point position statistically.     

Über Perowskite Ba2BBTeVIO6

On Perovskites Ba₂B B Te^VIO₆ Compounds of composition Ba₂BBTe^VIO₆ with B^I = Li, Na; B^III = La, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Yb, Y, In, Sc crystallize in a cubic 1:1 ordered perovskite structure. The vibrational spectroscopic investigations show, that more species of TeO₆ octahedra are present in the lattice.     

Ba6CoNb9O30: Ein neuer Vertreter der tetragonalen Wolframbronzen

Ba₆CoNb₉O₃₀: A New Compound of the Tetragonal Bronze Structure The hitherto unknown compound Ba₆CoNb₉O₃₀ was examined by X-ray single crystal work. (Space group C-P4bm; a = 1258.9; c = 400.9 pm) Co³⁺ and Nb⁵⁺ occupy a special position in an octahedral framework. The coordination of Ba²⁺ is discussed.     

Experimente zur Mischkristallbildung zwischen Zinktantalaten und -antimonaten: ZnTa2−xSbxO6 und Zn4Ta2−xSbxO9

Experiments about the Mixed Crystal Formation between Zincoxotantalates and -antimonates: ZnTa_2?xSb_xO₆ and Zn₄Ta_2?xSb_xO₉ In the area of substituted oxotantalates of zinc two new phases of the composition A: ZnTa_1·8Sb_0·2O₆ and B: Zn₄Ta_1·2Sb_0·8O₉ were prepared and investigated by X-ray single crystal technique. A crystallizes with tetragonal symmetry (space group D–P4₂/mnm, a = 4.7314; c = 9.2160 Å; Z = 2). B is monoclinic (space group C–C2/c; a = 15.103; b = 8.839; c = 10.378 Å; β = 93.81°; Z = 8). A crystallizes with trirutile structure, although there is a small replacement of Ta⁵⁺ by Sb⁵⁺. B maintains the Zn₄Ta₂O₉ structure. One of the point positions of the M⁵⁺ ions is occupied statistically by Ta⁵⁺/Sb⁵⁺ and Zn²⁺. B is a metastable compound.     

Zur Atomverteilung in Ba2SrIn2O6 mit einem Beitrag zur Existenz des Calciumferrat(III)-Typs bei Oxoindaten

On the Atomic Distribution in Ba₂SrIn₂O₆ with a Contribution to the Existence of the Calciumferrite-Type of Oxoindates (I) Ba₂SrIn₂O₆ and (II) Sr_0.93Ba_0.07In₂O₄ were prepared and investigated by single crystal X-ray technique. I crystallizes with tetragonal symmetry, space group D – I4/mmm, a = 4.168; c = 21.290 Å; Z = 2; II belongs to the orthorhombic space group D – Pnma, a = 9.858; b = 3.273; c = 11.520 Å; Z = 4. I shows in respect to the formerly investigated compound BaSr₂In₂O₆ an unexpected statistically distribution of Ba²⁺ and Sr²⁺ with the La₂SrCu₂O₆ type. II marks the range of existence of the calciumferrite type within the alkaline earth oxoindates in direction of large radii of M²⁺ ions.     

Untersuchungen an elektronenleitenden Oxidsystemen. XXI. Stabile spinelle ZnzNiMn2−zO4 und Vergleich mit Spinellen MgzNiMn2−zO4

Investigations on Electronically Conducting Oxide Systems. XXI [1] Stable Spinels Zn_zNiMn_2?zO₄ and Comparison with Spinels Mg_zNiMn_2?zO₄ Stable spinels are obtained in the result of substitution of Zn^II for manganese in the series Zn Ni^IIMnMnO₄ (O ? z ≤1). Different from spinels Mg Ni^IIMnMnO₄ (O ? z ?1)they don't be submitted to decomposition in air during slow cooling at medium temperatures. ZnNiMnO₄ (z=1) could not be prepared in a mono-phase state which is indicated by the composition of ZnNiMnO_3.96 deduced from analysis by oxidimetric titration. The comparably small variation of the specific electrical conductivity and of the activation energy observed in the range O ? z ? 2/3 for Zn_zNiMn_2?z is discussed in relation to larger alterations in the series Mg_zNiMn_2?zO₄. Structural interpretation is proposed based on the comparison of the molar volume of spinels M Mn₂O₄ (M: Mn, Fe, Co, Ni, Cu, Zn, Mg).     

Über Hexagonale Perowskite mit Kationenfehlstellen. I. Verbindungen vom Typ Ba2B□2/3ReVIIO6

On Hexagonal Perovskites with Cationic Vacancies. I. Compounds of the Type Ba₂B □_2/3Re^VIIO₆ Compounds of Type Ba₂B□_2/3Re^VIIO₆ are formed with B^III = Sm? Gd Ho? Lu, Y, Sc, In (yellow); Tb (black-brown); Dy (yellow-orange). They crystallize with B^III = Sm? Lu, Y and Sc in a rhombohedral layer structure of 12 L-type (space group R3 m; sequence: cchhcchhcchh) with 6 formula units in the unit cell.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXIV. Rhomboedrische 9 L-Stapelvarianten in den Systemen Ba3W M □ O9−x/2□x/2 mit MV = Nb,Ta

On Hexagonal Perovskites with Cationic Vacancies. XXIV. Rhombohedral 9 L Stacking Polytypes in the Systems Ba₃W M □O_9?x/2□_x?2 with M^V = Nb, Ta In the system Ba₃WNb□O_9?x/2□_x/2 stacking polytypes of rhombohedral 9 L type (sequence (hhc)₃; space group R3 m) can be prepared with ～1/3 ? × ? 2. For x = 2(Ba₃Nb₂□O₈□) two modifications are formed. In the corresponding Ta system the phase with is reduced to a smaller region with x ? 1/3.     

Schwingungsspektroskopische Untersuchungen an den geordneten Perowskiten ABIReVIIO6

Vibrational Spectroscopie Investigations on the Ordered Perovskites A B^IRe^VIIO₆ The vibrational spectra of the ordered perovskites AB^IRe^VIIO₆ with A = Ba, Sr; B = Li, Na are reported. For the cubic Ba compounds the force constants for the ReO₆ octahedra (O_h), the bond order in the Re? O distances have been calculated.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXXI. Die Systeme BaO?Re2O7?MO5 mit MV = Nb,Ta

On Hexagonal Perovskites with Cationic Vacancies. XXXI. Systems BaO? Re₂O₇? M O₅ with M^V = Nb, Ta In the systems BaO? Re₂O₇? MO₅ three quaternary oxides are formed, which belong to the perovskite stacking polytypes with cationic vacancies: Ba₈Re_7/2M□₃O₂₄ (M^V = Nb, Ta; rhombohedral 24 L type; sequence (hhhhchhc)₃; space group R3 m), Ba₄Re_9/8Ta_13/8□_5/4O₁₂ (rhombohedral 12 L type; sequence (hhcc)₃; space group R3 m) and the phases Ba₅BaRe_3/2?xM □O_15?x□_x (M^V = Nb, Ta; variants of a hexagonal 5 L type).