Ca-substitution and O-doping effects in superconducting Cu(Ba0.8Sr0.2)2(Yb1-xCax)Cu2O6+z obtained from neutron diffraction refinements

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© 1999 American Physical Society (APS). This is the accepted version of the following article: Karppinen, Maarit & Yamauchi, H. & Fujinami, K. & Nakane, T. & Peitola, K. & Rundlöf, H. & Tellgren, R. 1999. Ca-substitution and O-doping effects in superconducting Cu(Ba0.8Sr0.2)2(Yb1-xCax)Cu2O6+z obtained from neutron diffraction refinements. Physical Review B. Volume 60, Issue 6. 4378-4385. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.60.4378, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.60.4378.

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Journal ISSN

Volume Title

School of Chemical Technology | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

1999

Major/Subject

Mcode

Degree programme

Language

en

Pages

4378-4385

Series

Physical Review B, Volume 60, Issue 6

Abstract

Distinct calcium and oxygen doping effects were studied in the Cu(Ba0.8Sr0.2)2(Yb1−xCax)Cu2O6+z (Cu−1212:P) system by means of neutron diffraction and superconducting quantum interference device experiments in the wide substitution ranges of 0<~x<~0.35 and 0<z<1. The effectiveness of the two different ways to introduce holes into the CuO2 planes was compared both in respect to the capability to increase Tc and in terms of the hole production as estimated from neutron-diffraction data via bond-valence-sum calculation. Oxygen doping was found to increase the hole concentration less efficiently, and further, at a certain hole concentration value higher Tc values were obtained with calcium substitution than with oxygen doping. The two different hole-doping methods exhibited also different Tc vs Cu-O bond length relations. As a conclusion, the possible roles of the hole distribution in the in-plane Cu-O bond and the flatness of the CuO2 planes in determining the superconducting properties were recognized.

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Keywords

superconductors, neutron diffraction, oxygen doping, calcium

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Citation

Karppinen, Maarit & Yamauchi, H. & Fujinami, K. & Nakane, T. & Peitola, K. & Rundlöf, H. & Tellgren, R. 1999. Ca-substitution and O-doping effects in superconducting Cu(Ba0.8Sr0.2)2(Yb1-xCax)Cu2O6+z obtained from neutron diffraction refinements. Physical Review B. Volume 60, Issue 6. 4378-4385. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.60.4378.