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  • 1975-1979  (13)
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 424 (1976), S. 211-228 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Perovskite Phases of the System Ba2Y0,67U1-xWxO6A solid solution series is formed between the polymorphic perovskites Ba2Y0.67UO6 and Ba2Y0.67WO6 (cubic: a = 8.372 Å; hexagonal: a = 4× 5.881 Å and c = 4× 7.778 Å). The structure is cubic between x = 0.1 and 0.99 and for x 〉 0.95 hexagonal as well. Strong deviations from the ideal behaviour are detectabel with spectroscopic methods. The shape of the UO6 and WO6 octahedrons experiences only minor changes within the series.
    Notes: Die polymorphen Perowskite Ba2Y0,67UO6 und Ba2Y0,67 WO6 (kubisch: a = 8,372 Å; hexagonal: a = 4× 5,881 Å und c = 4× 7,778 Å) bilden Mischkristalle. Diese kristallisieren zwischen x = 0,1 und 0,99 kubisch und für x 〉 0,95 ebenfalls hexagonal. Mit spektroskopischen Methoden sind starke Abweichungen vom idealen Verhalten feststellbar. Die Gestalt der UO6- und WO6-Oktaeder erfährt innerhalb der Mischkristallreihe nur geringfügige Änderungen.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 425 (1976), S. 175-179 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polymorphism of Tungsten Perovskite Compounds Ba2SE0,67WO6The compounds Ba2SE0,67WO6 with SE = Gd—Lu are polymorphic. Above 1200°C the instable cubic modification (ordered perovskit with 4 formula units Ba2SE0,67□0,33WO6 per cell) transforms irreversibly into a hexagonal modification with completely filled cationic lattice. For Ba2Eu0,67WO6 the transformation is incomplete. With SE = Nd and Sm only the cubic modification is formed.
    Notes: Die Verbindungen Ba2SE0,67WO6 mit SE = Gd—Lu sind polymorph. Die instabile kubische Modifikation (geordneter Perowskit mit 4 Formeleinheiten Ba2SE0,67□0,33WO6 pro Zelle) wandelt sich oberhalb 1200°C irreversibel in eine hexagonale Modifikation mit aufgefülltem Kationengitter um. Bei Ba2Eu0,67WO6 ist die Umwandlung unvollständig. Mit SE = Nd und Sm konnte allein die kubische Modifikation erhalten werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    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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  • 5
    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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  • 6
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Perovskite Phases in the Systems AO—SE2O3—UO2,x with A = Alkaline Earth Metal and SE = Rare Earths, La, and Y. VIII. The Systems Ba2CaUO6—Ba2Gd0.67UO6 and Ba2CaUO6—Ba2Y0.67UO6The ordered perovskite Ba2CaUO6 forms a solid solution series with Ba2Gd0.67UO6 and Ba2Y0.67UO6, respectively. The deviations from the ideal behaviour are studied by x-ray, diffuse reflectance and vibrational methods.
    Notes: Der geordnete Perowskit Ba2CaUO6 bildet mit Ba2Gd0,67UO6 bzw. Ba2Y0,67UO6 eine lückenlose Mischkristallreihe. Die Abweichungen vom idealen Verhalten werden röntgenographisch und an Hand der diffusen Reflexions- und Schwingungsspektren untersucht.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 7
    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.
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 454 (1979), S. 43-48 
    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 Vacancies. IV. Compounds of Type Ba6B2III□Te3VIO18Compounds of the composition Ba6B2III□Te3VIO18 ≙ Ba2B2/3III□1/3TeVIO6, with BIII = Pr, Nd, Sm—Lu, Y crystallize with a cubic perovskite lattice. The cell parameters diminish as the size of BIII falls (BIII = Pr: a = 8.528 Å Lu: a = 8.334 Å). In contrast to the corresponding Perovskites with UVI and WVI no polymorphism is observed.
    Notes: Verbindungen der Zusammensetzung Ba6B2III□Te3VIO18 ≙ Ba2B2/3III□1/3TeVIO6 kristallisieren für BIII = Pr, Nd, Sm—Lu, Y im kubischen Perowskitgitter. Die Gitterkonstanten nehmen mit sinkender BIII-Größe ab (BIII = Pr: a = 8,528 Å Lu: a = 8,334 Å). Im Gegensatz zu den entsprechenden Perowskiten mit UVI und WVI wird keine Polymorphie beobachtet.
    Additional Material: 1 Ill.
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  • 10
    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.
    Type of Medium: Electronic Resource
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