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  • INSTRUMENTATION AND PHOTOGRAPHY  (2)
  • Inorganic Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 200-204 
    ISSN: 0044-2313
    Keywords: Alkaline Earth ; Praseodym ; Iron Oxide ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Ba6Pr2Fe4O15, Ba5SrPr2Fe4O15 and Ba5CaPr2Fe4O15Ba6Pr2Fe4O15 (I), Ba5SrPr2Fe4O15 (II), and Ba5CaPr2Fe4O15 (III) have been prepared by high temperature CO2-LASER techniques. (I)-(III) crystallize isotypic to the Ba6Ln2Al4O15 type, space group C6v4-P63mc, (I): a = 11.808(2), c = 6.894(5), Z = 2. Typical features of the crystal structure are face shared MO6 octahedra (M = Ba or Ba/Sr, Ba/Ca) and a statistical distribution of Ba and Pr in a ratio of 1 : 2 within double capped trigonal prisms of oxygen. Fe shows tetrahedral as well as octahedral coordination by oxygen. Calculation of coulomb terms of lattice energy indicate the stabilization of Pr3+ beside Fe3+ by the Ba6Ln2Al4O15 type.
    Notes: Ba6Pr2Fe4O15 (I), Ba5SrPr2Fe4O15 (II) und Ba5CaPr2Fe4O15 (III) wurden mit Hochtemperatur-CO2-LASER-Technik dargestellt. (I)-(III) kristallisieren mit hexagonaler Symmetrie, Raumgruppe C6V4-P63mc, (I): a = 11.808(2), c = 7,036(4) Å; (II): a = 11.689(2), c = 6.954(2) Å; (III): a = 11.602(6), c = 6.894(5) Å, Z = 2. Charakteristische Eigenschaften dieser Kristallstruktur sind flächenverknüpfte MO6-Oktaeder (M = Ba oder Ba/Sr, Ba/Ca) und eine statistische Verteilung von Ba und Pr im Verhältnis 1 : 2 in einem zweifach überkappten trigonalen Sauerstoffprisma. Fe zeigt sowohl tetraedrische als auch oktaedrische Sauerstoffkoordination. Berechnungen der Coulomb-Terme zur Gitterenergie deuten an, daß durch den Ba6Ln2A4O15-Typ Pr3+ neben Fe3+ stabilisiert wird.
    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 623 (1997), S. 1693-1698 
    ISSN: 0044-2313
    Keywords: Barium ; Copper ; Vanadyl Phosphate ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cu4O12 Groups Built of Square Planar CuO4 Polygones in the Barium Vanadyl Oxocuprate(II) Phosphate Ba(VO)Cu4(PO4)4Single crystals of Ba(VO)Cu4(PO4)4 have been prepared by solid state reactions just below the melting points of the reaction mixtures of BaP2O6, Cu3(PO4)2, CuO, V2O5 and V2O3 in evacuated closed quartz glas tubes. The compound crystallizes with tetragonal symmetry, Space group D42—P4212, a = 9.560(2), c = 7.160(2) Å, Z = 2. Special and new features of the crystal structure are to each other isolated Cu4O12 and (VO)(PO4)4 groups. The crystal chemistry of the Cu4O12 groups is discussed with respect to other compounds containing out of plane connected square planar MO4 polygones.
    Notes: Einkristalle von Ba(VO)Cu4(PO4)4 wurden mit Festkörperreaktionen dicht unterhalb des Schmelzpunktes des Reaktionsgemenges aus BaP2O6, Cu3(PO4)2, CuO, V2O5 und V2O3 in geschlossenen, evakuierten Quarzglasampullen dargestellt. Diese Verbindung kristallisiert tetragonal, Raumgruppe D42—P4212, mit a = 9,560(2), c = 7,160(2) Å, Z = 2. Besondere und neue Eigenschaften der Kristallstruktur sind zueinander isolierte Cu4O12- und (VO)(PO4)4-Gruppen. Die Kristallchemie der Cu4O12-Baugruppen wird mit Blick auf andere Verbindungen, die nicht in Ebenen verknüpfte MO4-Polygone aufweisen, diskutiert.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2011-08-18
    Description: A new type of bolometer detector for the millimeter and submillimeter spectral range is described. The bolometer is constructed of silicon using integrated circuit fabrication techniques. Ion implantation is used to give controlled resistance vs temperature properties as well as extremely low 1/f noise contacts. The devices have been tested between 4.2 and 0.3 K. The best electrical NEP measured is 4 x 10 to the -16th W/Hz to the 1/2 at 0.35 K between 1- and 10-Hz modulation frequency. This device had a detecting area of 0.25 sq cm and a time constant of 20 msec at a bath temperature of 0.35 K.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 910-914
    Format: text
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  • 4
    Publication Date: 2019-07-13
    Description: The MASCOT (MIT Astronomical Spectrometer/Camera for Optical Telescopes), an instrument capable of simultaneously performing both direct imaging and spectrometry of faint objects, is examined. An optical layout is given of the instrument which uses two CCD's mounted on the same temperature regulated detector block. Two sources of noise on the signal are discussed: (1) the CCD readout noise, which results in a constant uncertainty in the number of electrons collected from each pixel; and (2) the photon counting noise. The sensitivity of the device is limited by the sky brightness, the overall quantum efficiency, the resolution, and the readout noise of the CCD. Therefore, total system efficiency is calculated at about 15%.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Conference on Applications of Digital Image Processing to Astronomy; Aug 20, 1980 - Aug 22, 1980; Pasadena, CA
    Format: text
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