The Effect of Varying Ca-Content on the Structure of High-TC Superconductor (CaxLa1-x)(Ba1.75-xLa 0.25+x)Cu3O7-δ (x = 0.5, 0.6, and 0.8) Studied by Neutron Powder Diffraction

Yasushi Sato, Markus Valkeapää, Valery Petrykin, Minoru Osada, Sten Eriksson, Masato Kakihana, Håkan Rundlöf

Research output: Contribution to journalArticle

Abstract

We have performed neutron powder diffraction (NPD) experiments on polycrystalline powders with nominal compositions (Ca0.5La 0.5)(Ba1.25La0.75)Cu3O 7-δ, (Ca0.6La0.4)(Ba 1.15La0.85)Cu3O7-δ and (Ca0.8La0.2)(Ba0.95La1.05)Cu 3O7-δ. The diffraction patterns, analysed by the Rietveld method, show that all samples consist mainly of a tetragonal Y-123 type phase. Unit cell parameters a and c shorten as the calcium content increases: a = 3.8660(2), 3.8634(3), and 3.8624(5) Å; c = 11.6325(11), 11.6143(14), and 11.5822(20) Å for x-values 0.5, 0.6, and 0.8, respectively. For the x = 0.6 and 0.8 samples the Rietveld refinement of calcium occupancies and EDX analysis suggest that the actual composition is closer to x ≈ 0.5. However, since the lattice parameters do change, it is also suggested that at these higher doping levels calcium does enter the Y-site to a larger extent than for the x = 0.5 composition. This is also in accordance with previously reported values for the Tc, which decreases slighty as x changes from 0.5 to 0.6 and has a pronounced change from 80 K to 73 K for x = 0.6 and 0.8, respectively.

Original languageEnglish
Pages (from-to)361-364
Number of pages4
JournalMaterials Science Forum
Volume443-444
Publication statusPublished - 2004
Externally publishedYes

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Neutron powder diffraction
Superconducting materials
calcium
Calcium
neutrons
Chemical analysis
diffraction
Rietveld method
Rietveld refinement
Powders
Diffraction patterns
Lattice constants
Energy dispersive spectroscopy
lattice parameters
diffraction patterns
Doping (additives)
cells
Experiments

Keywords

  • High-T Superconductor
  • Neutron Powder Diffraction
  • Rietveld Analysis

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

The Effect of Varying Ca-Content on the Structure of High-TC Superconductor (CaxLa1-x)(Ba1.75-xLa 0.25+x)Cu3O7-δ (x = 0.5, 0.6, and 0.8) Studied by Neutron Powder Diffraction. / Sato, Yasushi; Valkeapää, Markus; Petrykin, Valery; Osada, Minoru; Eriksson, Sten; Kakihana, Masato; Rundlöf, Håkan.

In: Materials Science Forum, Vol. 443-444, 2004, p. 361-364.

Research output: Contribution to journalArticle

Sato, Yasushi ; Valkeapää, Markus ; Petrykin, Valery ; Osada, Minoru ; Eriksson, Sten ; Kakihana, Masato ; Rundlöf, Håkan. / The Effect of Varying Ca-Content on the Structure of High-TC Superconductor (CaxLa1-x)(Ba1.75-xLa 0.25+x)Cu3O7-δ (x = 0.5, 0.6, and 0.8) Studied by Neutron Powder Diffraction. In: Materials Science Forum. 2004 ; Vol. 443-444. pp. 361-364.
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AU - Sato, Yasushi

AU - Valkeapää, Markus

AU - Petrykin, Valery

AU - Osada, Minoru

AU - Eriksson, Sten

AU - Kakihana, Masato

AU - Rundlöf, Håkan

PY - 2004

Y1 - 2004

N2 - We have performed neutron powder diffraction (NPD) experiments on polycrystalline powders with nominal compositions (Ca0.5La 0.5)(Ba1.25La0.75)Cu3O 7-δ, (Ca0.6La0.4)(Ba 1.15La0.85)Cu3O7-δ and (Ca0.8La0.2)(Ba0.95La1.05)Cu 3O7-δ. The diffraction patterns, analysed by the Rietveld method, show that all samples consist mainly of a tetragonal Y-123 type phase. Unit cell parameters a and c shorten as the calcium content increases: a = 3.8660(2), 3.8634(3), and 3.8624(5) Å; c = 11.6325(11), 11.6143(14), and 11.5822(20) Å for x-values 0.5, 0.6, and 0.8, respectively. For the x = 0.6 and 0.8 samples the Rietveld refinement of calcium occupancies and EDX analysis suggest that the actual composition is closer to x ≈ 0.5. However, since the lattice parameters do change, it is also suggested that at these higher doping levels calcium does enter the Y-site to a larger extent than for the x = 0.5 composition. This is also in accordance with previously reported values for the Tc, which decreases slighty as x changes from 0.5 to 0.6 and has a pronounced change from 80 K to 73 K for x = 0.6 and 0.8, respectively.

AB - We have performed neutron powder diffraction (NPD) experiments on polycrystalline powders with nominal compositions (Ca0.5La 0.5)(Ba1.25La0.75)Cu3O 7-δ, (Ca0.6La0.4)(Ba 1.15La0.85)Cu3O7-δ and (Ca0.8La0.2)(Ba0.95La1.05)Cu 3O7-δ. The diffraction patterns, analysed by the Rietveld method, show that all samples consist mainly of a tetragonal Y-123 type phase. Unit cell parameters a and c shorten as the calcium content increases: a = 3.8660(2), 3.8634(3), and 3.8624(5) Å; c = 11.6325(11), 11.6143(14), and 11.5822(20) Å for x-values 0.5, 0.6, and 0.8, respectively. For the x = 0.6 and 0.8 samples the Rietveld refinement of calcium occupancies and EDX analysis suggest that the actual composition is closer to x ≈ 0.5. However, since the lattice parameters do change, it is also suggested that at these higher doping levels calcium does enter the Y-site to a larger extent than for the x = 0.5 composition. This is also in accordance with previously reported values for the Tc, which decreases slighty as x changes from 0.5 to 0.6 and has a pronounced change from 80 K to 73 K for x = 0.6 and 0.8, respectively.

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