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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 374-376 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using an electron diffraction technique, the thicknesses of the (nonorthorhombic) twin boundary layers were measured for pure and alloyed YBa2(Cu1−xMx)3O7−δ. Boundary thickness varied from ∼0.7 nm for M=Ni, x=0.02, and δ(approximately-equal-to)0 to ∼2.6 nm for M=Al, x=0.02, and δ(approximately-equal-to)0, while it was ∼1.0 nm for a pure YBa2Cu3O7. High-resolution transmission electron imaging of similar specimens supports the existence of such twin boundary layers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 331-335 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Effects of oxygen partial pressure PO2 during low temperature postheat treatments on the superconducting properties of silver-sheathed Bi2Sr2CaCu2Oy tapes were investigated. The critical temperature Tc of the resulting tapes changes systematically with PO2. This variation of Tc is attributed to the change of electronic carrier (hole) concentration by the observation of oxygen K-edge absorption spectra. The intragranular critical current density Jc is essentially unaffected by the heat treatment, while deterioration in grain connectivity is observed in the specimens treated in reduced-oxygen atmospheres. The change of anisotropy in Jc with respect to crystallographic orientations is also quite small for the variation of PO2. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 6 (1999), S. 755-757 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 49 (1993), S. 141-148 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A method is described for the refinement of modulated structures from a combined set of single-crystal and powder diffraction data or from powder data only. The method is especially useful when information on light atoms is to be obtained and no single crystals of suitable size for neutron diffraction are available. The program in which the method is encoded allows for differences in composition between the single-crystal and powder samples. Application to the incommensurately modulated superconductor Bi2Sr2CaCu2O8+y (2212) using powder neutron and single-crystal X-ray data confirms that the oxygen modulation in the Bi–O layer is saw-tooth-like, as observed in the preceding study based solely on X-ray data [Petricek, Gao, Lee & Coppens (1990). Phys. Rev. B, 42, 387–392], but with improved accuracy in the resulting parameters. The extra oxygen content is explicitly related to the modulation model and corresponds to 0.14–(4) per formula unit. With the refined site occupancies for the heavy atoms and the results of an anomalous-scattering study on the bismuth distribution [Coppens, Lee, Gao & Sheu (1991). J. Phys. Chem. Solids, 52, 1267–1272], a copper valency of 2.31 is obtained for the single-crystal sample. The powder value of 2.40 is somewhat less reliable as no anomalous-scattering data are available for the powder sample.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 337 (1989), S. 720-721 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the prototypical hole-doped superconductor system La2_xSrxCuO4, each Cu atom is surrounded by a tetragonally distorted octahedron of O atoms. In the undoped compound, each Cu ion is in a 3d9 configuration (2+ valence), whereas the 2p states of the oxygen atoms are fully occupied. When Sr2+ is ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 340 (1989), S. 349-349 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] TRANQUADA ET AL. REPLY-We agree with Sampathkumaran that further char-acterization of this material is required, but we stand by our previous analysis of the near-edge structures. The changes observed at the copper K edge as a result of cerium doping are small on an absolute scale; they are ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 10 (1973), S. 203-206 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The superconducting transition temperature of barium was redetermined as a function of pressure. The results are at variance with the work of Il'ina and Itskevich. Apparently mixed phase samples occurred rather generally. We trust that at least the overall shape of the pressure dependence ofT c has been correctly determined.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: The superconducting properties of transition metal sulfides, selenides, and phosphides having the cubic NaCl structure are described. Binary compounds found to be superconducting are ThS, ScSe, ThSe, HfP, and ThP. More detailed information about the known superconductors Zr1−xS, LuS, Sc1−xS, YS, and ZrP is presented. Transition temperature was established as a function of composition for Zr-S, Sc-S, and Y-S NaCl-structure systems. Superconductivity at high pressure was determined in several systems. Some low-temperature specific heat capacity results, room-temperature magnetic susceptibility, and electrical resistance measurements between 2 K and room temperature are reported. Some information is presented about the rhombohedrally distorted compounds ZrSe and HfS. Results of NaCl-structure solid solution (metal replacement) synthesis (including superconductivity data) are reported for (Zr, Sc)-S, (Zr, Y)-S, (Zr, Ti)-S, (Zr, Hf)-S, (La, Y)-S and (Y, Th)-S. We find that superconductivity occurs generally in these materials, and that these compounds have much in common with the better known NaCl defect structure carbides and nitrides.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The n-type cuprate superconductor and closely related samples of the general form Nd2−x Ce x CuO4−y have been studied with the muon spin relaxation technique. Non-super-conducting samples display antiferromagnetism (AFM) withT N below 150 K, the value being dependent upon both Ce concentration and oxygen depletion. The results are interpreted in terms of carrier concentration.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 8 (1988), S. 307-309 
    ISSN: 0741-0581
    Keywords: Electron energy loss spectroscopy ; Varying O2 content ; Crystallographic orientation dependence of oxygen near edge features ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The high Tc superconducting material YBa2Cu3O7 shows a complex relationship between microstructure and oxygen content, which are controlled by length of heat treatment, atmosphere, and quench rate. An AEM investigation studying changes in the oxygen near edge features was undertaken. Electron energy loss spectroscopy (EELS) measurements have the important advantage that they can be made on single crystal grains, allowing orentation-dependent studies. Both ion-milled and crushed samples with varying O2 content were analyzed. The structure of YBaCu3O7 was determined by neutron diffraction to be orthorhombic with distinct Cu-O chains along the b-axis as well as Cu-O planes in the a - b plane. Therefore, by looking for a crystallographic dependence of the oxygen K-edge one might be able to distinguish inequivalent oxygen atoms by their core level binding energy and correlate site occupancy with varying O2 content. The EELS results on the oxygen K-edge are strongly dependent on oxygen content, most noticeably when the c-axis is parallel to the electron beam.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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