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Modulated structure of the superconducting compounds Bi2Sr2Ca n-1Cu n O y withn=1 and 2 (1989)

Li, J. Q. ; Chen, C. ; Yang, D. Y. ; [weitere]

Springer

The European physical journal 74 (1989), S. 165-172

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ISSN: 1434-6036

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract The incommensurate modulated structures of high-T c superconducting phases Bi2Sr2Ca n−1Cu n O y (n=1 and 2) have been studied using symmetry properties of four-dimensional super-spacegroups and electron diffraction as well as high resolution electron microscopy are used to describe the properties of the incommensurate modulated structure in the compounds. The main results are planar monoclinic symmetryP B 2/b 11 orP B b 1 for Bi2Sr2CuO y (n=1) and orthorhombic symmetryN 111 Bbmb orN 111 Bb2b for Bi2Sr2CaCu2O y (n=2). The temperature dependence of the modulated structure of Bi2Sr2CaCu2O y has been investigated from −190°C to 800°C. Some structure properties of Bi2Sr2Ca2Cu3O y (n=3) are presented for comparison.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01307382

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Digitale Medien

The crystal structure and superconductivity of the new superconducting phase TlSr2Ca0.5Er0.5Cu2O6.75 (1989)

Liang, J. K. ; Zhang, Y. L. ; Rao, G. H. ; [weitere]

Springer

The European physical journal 76 (1989), S. 277-281

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ISSN: 1434-6036

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract The crystal structure of the superconducting phase TlSr2Ca1−xErxCu2O6.5+x/2 (x=0.5) in the Tl−Sr−Ca−Er−Cu−O system was determined using the X-ray powder diffraction method. It belongs to a primary tetragonal cell with lattice constantsa=3.798,c=12.014 Å, with a space group ofD 4h 1 −P4/mmm. Each unit cell contains one formula unit. The positions of ions in the unit cell are as follows: 0.5 Ca and 0.5 Er cations disorderly occupy 1(d) equivalent point position, each with an occupation factor of 0.5; 1. Tl cation occupies the equivalent point position 1 (a); 2. Cu cations occupy 2 (g) withz=0.365; 2 Sr cations occupy 2(h) withz=0.220; 7 O anions respectively occupy 1(c), 2(g), (z=0.165) and 4(i) (z=0.365) equivalent point positions. The zero-resistance superconducting transition temperatureT c (0) decreased slightly with increased Er content in the Tl−Sr−Ca−Er−Cu−O system. The crystal structure of TlSr2Ca0.5Er0.5Cu2O6.75 is very similar to that of TlBa2CaCu2O6.5 in the Tl−Ba−Ca−Cu−O system or RBa2Cu3O7 in the R−Ba−Cu−O system. In the superconducting phase with an oxygen-deficient perovskite-like structure, the similarity of cation-oxygen coordination polyhedra is important for cation substitution.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01321903

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Digitale Medien

Composition and superconductivity in Bi-Sr-Ca-Cu-O and substituted systems (1989)

Che, G. C. ; Liang, J. K. ; Chen, W. ; [weitere]

Springer

Journal of materials science 24 (1989), S. 1725-1728

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ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract The composition of the superconducting phase Bi4(Sr3±x Ca3∓x )Σ=6Cu4O16, has been determined by means of a sysmetic investigation of the relationship between composition and superconductivity, and phase analysis. The superconducting phase belongs to tetragonal system witha=0.3825 nm,c=3.082 nm, space group (S.G.) 14/mmm. The effect of strontium and calcium contents in the Bi(Sr1±x Ca1∓x )Σ=2Cu2O5.5, system and substitution in the Bi1−x A x SrCaCu2O5 (A=V, Gd, Y) and BiSrCa1−x Pb x Cu2O5.05 systems on superconductivity, have been investigated. In the Bi-Sr-Ca-Cu-O system, there are two superconducting phases corresponding to transition temperatures of 110 and 80 K, respectively. The difference between the two superconducting phases may be due to the stacking difference of atoms along thec direction in the structure and their oxygen content.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01105697

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