The superconducting bismuth-based mixed oxides

E. V. Antipov, N. R. Khasanova, J. S. Pshirkov, S. N. Putilin, C. Bougerol, O. I. Lebedev, G. Van Tendeloo, A. N. Baranov, Y. W. Park

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5 Citations (Scopus)

Abstract

The present paper describes the synthesis, characterization of mixed-valence bismuthates with 3- or 2-dimensional perovskite-like structures and structural criteria that influence superconductivity in these compounds. Single-phase samples of Sr1-xKxBiO3 were prepared for the broad range of K-content: 0.25 ≤ x ≤ 0.65. For these bismuthates the symmetry of the structure changes from monoclinic to orthorhombic and finallly to tetragonal upon increasing the K-content thus resulting in the decrease of the Bi-O distances and reduction of the network distortions. Superconductivity with maximum Tc = 12K exists in the narrow range (x = 0.5 - 0.6) within the stability field of the tetragonal phase (0.33 ≤ x ≤ 0.65), when the 3-dimensional octahedral framework has close to the ideal perovskite structure arrangement. At the same time compositions with close to optimal Bi-valence (x = 0.33 and 0.43) do not show any sign of superconductivity, probably, due to structural distortions. The layered type (Ba,K) 3Bi2O7 and (Ba,K) 2BiO4 bismuthates belonging to the An+1BnO3n+1 homologous series were investigated. Buckling of the (BiO2) layers in the structure of the n = 2 member was revealed. The formation of the n=1 bismuthate was found by Electron Microscopy and X-ray powder diffraction studies. Both types of compounds are considered to be possible candidates for new superconducting materials among bismuthates.

Original languageEnglish
Pages (from-to)575-587
Number of pages13
JournalJournal of Low Temperature Physics
Volume131
Issue number3-4
DOIs
Publication statusPublished - May 2003
Externally publishedYes

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