Über Perowskitphasen in den Systemen BaO–SE2O3–UO2,x mit SE = Seltene Erden,La und Y. I. Verbindungen der Zusammensetzung Ba2SE0,67UO6 und Ba2SE0,67UO5,5

In the BaO–SE₂O₃–UO_2,x-system the formation of the polymorphic ordered perovskites Ba₂SE_0,67UO₆ ist observed. At the reduction of the former the ordered perovskites Ba₂SE_0,67UO_5,5 are formed, which contain U(V) only. According to the results of the magnetic and spectroscopic investigations the pentavalent uranium occupies the centers of slightly or strongly distorted octahedrons, while U(VI) is partly forming UO-groups. The rare earths are always present in the trivalent state. – The structural relations to the ordered perovskite A₂BB′O₆ are discussed.     

Über Perowskitphasen in den Systemen AO?SE2O3?UO2.x mit A = Erdalkali und SE = Seltene Erden,La und Y. IV. Verbindungen der Zusammensetzung Sr2SE0,67UO5,5 und Sr2SE0,67UO6

On Perovskite Phases in the Systems AO? SE₂O₃? UO_2,x with A = Alkaline Earth Metal and SE = Rare Earths, La, and Y. IV. Compounds of the Composition Sr₂SE_0,67UO_5,5 and Sr₂SE_0,67UO₆ In the SrO? SE₂O₃? UO_2,x-system the formation of slightly monoclinic distorted rhombic perovskite phases Sr₂SEU⁵⁺O_5,5 is observed. According to the results of the spectroscopic investigations the pentavalent uranium is octahedrally surrounded by oxygen. There are three kinds of U? O-octahedrons to distinguish. By oxydation of Sr₂SE_0,67UO_5,5 the cubic perovskite phases Sr₂SE_0,67UO₆ with hexavalent uranium are obtained. – The structural relations between the perovskites A₂SE_0,67UO_5,5 and A₂SE_0,67UO₆ with A = Ba, Sr are discussed.     

Über Perowskitphasen in den Systemen BaO–SE2O3–UO2,x mit SE = Seltene Erden,La und Y. II. Verbindungen der Zusammensetzung Ba2(SE0,67U0,33)UO6,17

In the BaO–SE₂O₃–UO_2.x system the formation of the compounds Ba₂(SE_0,67U_0.33)UO_6.17 is observed. They crystallize in a pseudocubic ordered perovskite lattice, and contain tetravalent and pentavalent uranium in the ratio 1:3. Their magnetic and spectroscopic properties are reported.     

Über die Eigenschaftsänderungen beim Einbau von Tav in Ba2Gd0,67UO6

The Variation of Properties by Incorporation of Ta^v in Ba₂Gd_0.67UO₆ In Ba₂Gd□_0.33U^VIO₆ the complete substitution of U^VI by Ta^V is only possible by filling up the gadolinium vacancies (Ba₂Gd_0.67+0.33xU_1?xTa_xO₆), whereas in the series Ba₂Gd_0.67U_1?yTa_yO_6–0.5y the phase boundary is reached with y = 0.1. Depending on x the variation of the properties is studied by X-ray and spectroscopic methods.     

Über die Polymorphie der Wolframperowskite Ba2SE0,67WO6

Polymorphism of Tungsten Perovskite Compounds Ba₂SE_0,67WO₆ The compounds Ba₂SE_0,67WO₆ with SE = Gd? Lu are polymorphic. Above 1200°C the instable cubic modification (ordered perovskit with 4 formula units Ba₂SE_0,67□_0,33WO₆ per cell) transforms irreversibly into a hexagonal modification with completely filled cationic lattice. For Ba₂Eu_0,67WO₆ the transformation is incomplete. With SE = Nd and Sm only the cubic modification is formed.     

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 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.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXX. 5 L-Stapelvarianten in den Systemen BaO?Re2O7?Sb2O5 und BaO?WO3?Sb2O5

On Hexagonal Perovskites with Cationic Vacancies. XXX. 5 L Stacking Polytypes in the Systems BaO — Re₂O₇? Sb₂O₅ and BaO? WO₃? Sb₂O₅ In the systems BaO? Re₂O₇? Sb₂O₅ and BaO? WO₃? Sb₂O₅ phases of composition Ba₅BaRe Sb□O_15?x□_x (x = 0 up to x ? 3/4) and Ba₅BaWSb□O_15?x/2□_x/2 (x ? 3/2 up to x ? 2) are existent, which have an orthorhombic distorted 5 L structure. The pure Sb compound has to be formulated as Ba₃BaSb₂O₉ and crystallize in an orthorhombic variant of the hexagonal BaTiO₃ type.     

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.     

Zur Kristallstruktur von Ba2ZnO3

On the Crystal Structure of Ba₂ZnO₃ Single crystals of Ba₂ZnO₃ were prepared by solid state reaction. It crystallizes monoclinic: space group C ? C12/c1; a = 5.833; b = 11.376; c = 12.585 Å; β = 93.63°; Z = 8. The crystal structure is characterised by [ZnO₃] chains along [100]. They are connected by Ba²⁺ in seven fold oxygen coordination.     

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.     

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.     

Über Erdalkalimetalloxothallate. II. Darstellung und Kristallstruktur von Ba2Tl2O5

On Alkaline Earth Metal Oxothallates. II. Preparation and Crystal Structure of Ba₂Tl₂O₅ Ba₂Tl₂O₅ was prepared and investigated by X-ray single crystal methods (space group D? Pcmn, a = 6.264, b = 17.258, c = 6.05 Å) Ba₂Tl₂O₅ is isotypic with Ca₂Fe₂O₅.     

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. 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).     

Gibt es „Wolframylgruppierungen”︁? Über Perowskitphasen im System Ba2Y0,67UO6?Ba2CaWO6

Do ? Wolframyl Groups ”? Exist? On Perovskite Phases in the System Ba₂Y_0,67UO₆ ? Ba₂CaWO₆ In the system Ba₂Y_{0.67(1? x)}Ca_xU_{1? x}W_xO₆ a solid solution series is formed up to x ? 0.85. The properties are studied by x-ray and spectroscopic methods.     

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.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXVII. Die Systeme Ba4−xSrxBIIRe2□O12′, Ba4BCaxRe2□O12 und Ba4−xLaxBIIRe2−xWx□O12 mit BII = Co,Ni

On Hexagonal Perovskites with Cationic Vacancies. XXVII. Systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄B Ca_xRe₂□O₁₂, and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ with B^II = Co, Ni In the systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄BCa_xRe₂□O₁₂ and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ (B^II = Co, Ni) hexagonal perovskites with a rhombohedral 12 L structure (general composition A₄BM₂□O₁₂; sequence (hhcc)₃; space group R&3macr;m) are observed. With the exception of Ba₄NiRe₂□O₁₂ the octahedral net consists of BO₆ single octahedra and M₂□O₁₂ face connected blocks (type 1). In type 2 (Ba₄NiRe₂□O₁₂) the M ions are located in the single octahedra and in the center of the groups of three face connected octahedra. The two outer positions of the latter are occupied by B ions and vacancies in the ratio 1:1. The difference between type 1 and 2 are discussed by means of the vibrational and diffuse reflectance spectra.     

Über hexagonale Perowskite mit Kationenfehlstellen. XIV Die rhomboedrischen 12 L-Stapelvarianten Ba2La2BII(W□O12)

On Hexagonal Perovskites with Cationic Vacancies. XIV. The Rhombohedral 12 L-Stacking Polytypes Ba₂La₂B^II(W □O₁₂) Rhombohedral 12 L-stacking polytypes with cationic vacancies of type Ba₂La₂B^II-(W□O₁₂) are reported for B^II = Mg, Zn (white), Ni(light brown) and Co(brown). They crystallize in the space group R3 m, sequences (3 )(1) ? (hhcc)₃. For B^II = Cu, as a consequence of the Jahn Teller effect, a triclinic distorted lattice is observed.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXVI. Ba12Ba2 2/3M 1/3□2O33□3 (MV = Nb,Ta) – die ersten Stapelvarianten eines rhomboedrischen 36 L-Typs

On Hexagonal Perovskites with Cationic Vacancies. XXVI. Ba₁₂Ba_{2 2/3}M _1/3□₂O₃₃□₃ (M^V = Nb, Ta) – the First Stacking Polytypes of a Rhombohedral 36 L-Type In the systems BaO? MO₅(M^V = Nb, Ta) for a Ba:M^V ratio of 2:1 polymorphism is observed. Here the low temperature modifications are described. They crystallize in a rhombohedral 36 L structure with three formula units Ba₁₂Ba_{2 2/3}M _1/3□₂O₃₃□₃ for the trigonal setting (M^V = Nb: a = 5.92₂ Å; c = 93.₂₅ Å; Ta: a = 5,92₂ Å; s = 93.4 Å).