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  • 11
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vibrational Investigations on Ordered Perovskites A2IIBMO6. I. MO6 Octahedra: Symmetry, Force Constants, and DistancesAccording to their vibrational spectra the ordered perovskites A2IIBMO6 can be divided in three groups: compound with 1. MO6 octahedra of symmetry Oh, 2. MO6 octahedra of lowered point symmetry, 3. different kinds of MO6 octahedra. The force constants, M—O distance and bond order are calculated.
    Notes: Die geordneten Perowskite A2IIBMO6 Können auf Grund ihrer Schwingungs-spektren in 3 Gruppen eingeteilt werden: Verbindungen mit 1. MO6-Oktaedern der Symmetrie Oh, 2. MO6-Oktaeder mit erniedrigter Punktsymmetrie, 3. mit verschiedenen Sorten an MO6-Oktaedern. Die Kraftkonstanten, M—O-Abstände und Bindungsgrade werden berechnet.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 439 (1978), S. 250-254 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the System Ba2Gd2/3□1/3U1-xWxO6 and Hexagonal Perovskites of an 18-Layer TypeIn the system Ba2Gd2/3□1/3U1-xWxO6 the formation of a continuous solid solution series is observed. With x ≤ 0.9 the mixed crystals have a cubic 1:1 ordered perovskite structure. With x ≥ 0.95 the compounds are polymorphic: besides an cubic 1:1 ordered perovskite type for x = 0.95; 0.99 and 1.00 one hexagonal layer structure exists. This lattice is in all cases rhombohedral (space group R3m) and represents an 18 L-type. Likewise the compounds Ba2B2/3III□1/3WVIO6 with BIII = Tb-Lu and Y belong to the 18 L-type.
    Notes: Im System Ba2Gd2/3□1/3U1-xWxO6 wird lückenlose Mischbarkeit beobachtet. Für x ≤ 0,9 kristallisieren die Mischkristalle in einem kubischen 1:1 geordneten Perowskitgitter. Für x ≥ 0,95 tritt Polymorphie auf: neben den kubischen 1:1 geordneten Perowskittyp wird mit x = 0,95; 0,99 und 1,00 eine hexagonale Stapelvariante beobachtet. Dieses Gitter ist jeweils rhomboedrisch (Raumgruppe R3m) und stellt eine 18-Schichtenstruktur dar. Die Verbindungen Ba2B2/3III□1/3WVIO6 mit BIII = Tb-Lu und Y besitzen ebenfalls eine 18-Schichtenstruktur.
    Additional Material: 3 Tab.
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  • 13
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Hexagonal Perovskites with Cationic Vacancies. V. Structure Determination on H—Ba2Lu2/3 □ 1/3WO6  -  a Novel Rhombohedral Stacking Polytype with 18 LayersCompounds of type Ba2B2/3III□1/3WVIO6 with BIII — Gd - Lu, Y are polymorphic They crystallize in a cubic 1:1 ordered perovskite structure and in a new rhombohedral perovskite stacking polytype of 18 L respectively. By intensity calculations out of the three possible stacking sequences (4)(2), (5)(1) and (3)1(1)1 (all space group R3m) the sequence (5)(1) can be selected. For H—Ba2Lu2/3□1/3WO6 the refined R′ factor is 14.1%. The structure contains groups of three octahedra connected with another by common faces which are linked with each other by three corner sharing octahedra. In the block of three face sharing octahedra the central octahedral lattice site is vacant, the two outer positions are occupied by tungsten atoms. According to this distribution a direct contact of occupied face sharing octahedra is absent.
    Notes: Verbindungen vom Typ Ba2B2/3III□1/3WVIO6 sind für BIII = Gd - Lu, Y polymorph. Neben einer kubischen 1 : 1 geordneten Perowskitstruktur kristallisieren sie in einer neuen rhomboedrischen Stapelvariante vom 18 L-Typ. Intensitätsberechnungen zeigen, daß von den drei möglichen Stapelfolgen (4)(2), (5)(1) und (3)1(1)1 (jeweils R.G. R3m) die Abfolge (5)(1) zutrifft. Für H—Ba2Lu2/3□1/3 WO6 beträgt der verfeinerte R′-Faktor 14,1%. Die Struktur besteht aus Dreier blöcken von flächenverknüpften Oktaedern, die untereinander durch drei über Ecken verknüpfte Oktaeder verbunden sind. Die zentrale Oktaedermitte der Dreierblöcke ist nicht besetzt, in den beiden äußeren Oktaederpositionen dieser Gruppierung befinden sich Wolframatome. Ein direkter Kontakt von besetzten flächenverknüpften Oktaedern wird dadurch vermieden.
    Additional Material: 1 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 445 (1978), S. 152-156 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Compounds of the Type Ba3RE2TeO9In the BaO—RE2O3—TeO3 system homogeneous perovskite compounds of formula Ba3RE2TeO9 with RE = Nd, Sm-Gd, Dy-Lu, and Y are formed under special preparation conditions. With RE = ND and Sm A monoclinic lattice is observed whereas for the other RE a primitive cubic (a = 4.303 Å (Eu) to a = 4.214 Å (Lu)) lattice is found.
    Notes: Im System BaO—SE2O3—TeO3 sind einheitliche Perowskite der Zusammensetzung Ba3SE2TeO9 für SE = Nd, Sm-Gd, Dy-Lu und Y unter speziellen Darstellungsbedingungen erhältlich. Sie Kristallisieren mit SE = Nd und Sm monoklin, mit übrigen SE ist das Gitter Kubisch Primitiv (a = 4,303Å (Eu) bis a = 4, 214 Å (Lu)).
    Additional Material: 1 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 407 (1974), S. 181-192 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the System Ba2Sm 0.67U1-xWxO6The ordered perovskites Ba2Sm0.67UO6 and Ba2Sm0.67 WO6 are forming a complete serie of solid solutions with 4 formula units Ba2Sm0.67U1-xWxO6 in the unit cell. By diffuse reflectance and i.r.-spectroscopic measurements the relations between color and constitution are shown.
    Notes: Die geordneten Perowskite Ba2Sm0,67UO6 und Ba2Sm0,67WO6 bilden eine lückenlose Reihe von Mischkristallen mit vier Formeleinheiten Ba2Sm0.67U1-xWxO6 pro Elementarzelle. Die Zusammenhänge zwischen Farbe und Konstitution werden an Hand der diffusen Reflexionsspektren und der IR-Spektren aufgezeigt.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Hexagonal Perovskites with Cationic Vacancies. VIII. Vibrational Spectroscopic Investigations on Rhombohedral 18 L-Stacking Polytypes Ba6BIII2□WVI3O18The vibrational spectra of the 18 L stacking polytypes Ba6BIII2□W3O18 (space group R3m; sequence (hhcccc)3) with BIII = Lu, Y are reported. The octahedral net consists of W2□O12 and WO6 groups, which are isolated from each other by the Ba and B ions. An assignment of the vibrational frequencies has been made with the aid of factor group analysis. For the W2□O12 block a complete for constant calculation is reported.
    Notes: Die Schwingungsspektren der 18 L-Stapelvarianten Ba6BIII2□W3O18 (R. G. R3m; Stapelfolge (hhcccc)3) mit BIII = Lu, Y werden mitgeteilt. Das Oktaedergerüst besteht aus isolierten, in das Gitter der Ba- und B-Ionen eingebauten W2□O12- und WO6-Gruppen. Die Schwingungsfrequenzen lassen sich entsprechend der Faktorgruppenanalyse zuordnen. Für den W2□O12-Block wird über eine vollständige Kraftkonstatenberechnung berichtet.
    Additional Material: 1 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 465 (1980), S. 183-185 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Hexagonal Perovskites with Cationic Vacancies. XX. Ba6Nb4Zr□o18 - a New Stacking Polytype with a Rhombohedra1 18 L StructureThe white Ba6Nb4Zr□O18 crystallizes in a rhombohedral 18 L structure (a = 5.821 Å; c = 42.63 Å; space group R3m) with three formula units for the trigonal setting (ϱexp = 6.05 g/cm3; ϱcalc = 6.271 g/cm3). The corresponding TiIV and HfIV compounds, Ba6Nb4Zr□O18 and Ba6Nb4Hf□O18, are isotypic.
    Notes: Das weiße Ba6Nb4Zr□O18 kristallisiert in einer rhomboedrischen 18 L-Struktur (a = 5,821 Å; c = 42,63 Å; R. G. R3m) mit drei Formeleinheiten pro trigonal aufgestellter Zelle (ϱgef = 6,05 g/cm3; ϱber = 6,271 g/cm3). Die entsprechenden Verbindungen mit TiIV und HfIV, Ba6Nb4Ti□O18 und Ba6Nb4Hf□O18 sind isotyp.
    Additional Material: 1 Tab.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 431 (1977), S. 134-143 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polymorphism of Perovskite Compounds Ba2SE0.67WVIO6. II. The Systems Ba2Nd0.67(1-x)Y0.67xWO6 and Ba2Nd0.67W1-xUxO6In the system Ba2Nd0.67(1-x)Y0.67xWO6 the formation of a continuous series of mixed crystals with cubic 1:1 ordered perovskite structure is observed. The existence of a hexagonal modification is confined to the Y-rich side (x ≥ 0,9). In the Ba2Nd0.67W1-xUxO6 series only for x ≤ 0,25 homogeneous cubic perovskites are obtained. In contrast to systems with other rare earths the Nd series show uncommon optical properties.
    Notes: Im System Ba2Nd0,67(1-x)Y0,67xWO6 wird die lückenlose Bildung von Mischkristallen mit kubischer 1:1 geordneter Perowskitstruktur beobachtet. Die Existenz einer hexagonalen Modifikation ist auf die Y-reiche Seite (x ≥ 0,9) beschränkt. In der Reihe Ba2Nd0,67W1-xUxO6 können einheitliche kubische Perowskite allein für x ≤ 0,25 erhalten werden. Im Gegensatz zu Systemen mit anderen Seltenen Erden zeichnen sich die Nd-Reihen durch ungewöhnliche optische Eigenschaften aus.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 431 (1977), S. 144-152 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Ordered Perovskites with Cationic Defects. The Systems Ba2MgWO6—Ba2Y0.67WO6 and Ba2CaWO6—Ba2Y0.67WO6The perovskites Ba2MgWO6 and Ba2CaWO6 show complete miscibility with Ba2Y0.67WO6. The mixed crystals have a cubic 1:1 ordered perovskite structure, whereas with x an increase of cationic defects is observed (systems Ba2B1-xIIY0.67x□0.33xWO6). Depending on the occupation of the neighbouring positions different types of WO6 octahedra are present. The transformation cubic → hexagonal, which is characteristic for Ba2Y0.67WO6, is oppressed by the incorporation of BII ions.
    Notes: Die Perowskite Ba2MgWO6 bzw. Ba2CaWO6 zeigen mit Ba2Y0,67WO6 vollständige Mischbarkeit. Die in einem kubischen 1:1 geordneten Perowskitigitter kristallisierenden Mischkristalle enthalten mit x steigende Mengen an Kationenfehlstellen (Systeme Ba2B1-xIIY0,67x □0,33xWO6). In Abhängigkeit von den Nachbarschaftsverhältnissen liegen verschiedene Typen an WO6-Oktaedern nebeneinander vor. Die für Ba2Y0,67WO6 charakteristische Umwandlung kubisch → hexagonal wird durch Einbau von BII-Ionen unterdrückt.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 437 (1977), S. 197-202 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vibrational Spectroscopic Investigation on Perovskite Type Variants Ba2B0.67III□0.33MVIO6 and their Solid Solutions with Ba2BIIMVIO6In the perovskite typ variants Ba2B0.67III□0.33MVIO6 with MVI = W, U, Te several kinds of MVIO6 octahedra are to distinguish. The study of the solid solutions Ba2B1-xIIY0.67x□0.33xWO6 (BII = Mg, Ca) shows, that in the lattice no more than three different types of WO6 octahedra can be present.
    Notes: Die Perowskitvarianten Ba2B0,67III□0,33MVIO6 mit MVI = W, U, Te enthalten mehrere Sorten an MVIO6-Oktaedern. Aus der Untersuchung der Mischkristallsysteme Ba2B1-xIIY0,67x□0,33xWO6 (BII = Mg, Ca) geht hervor, daß im Gitter nicht mehr als drei verschiedene Typen von WO6-Oktaedern vorhanden sein können.
    Additional Material: 1 Tab.
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