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Defect‐Chemical Aspects in the Synthesis of Metallic Conductors La 1 – x Ba x CuO 3 ( x = 0.0 to 0.5)
Author(s) -
Dwivedi Anurag,
Rodriguez Mark A.,
Cormack Alastair N.
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb07232.x
Subject(s) - oxygen , metal , solid solution , electrical resistivity and conductivity , conductivity , crystallography , x ray crystallography , electrical conductor , materials science , chemistry , analytical chemistry (journal) , mineralogy , physics , metallurgy , diffraction , organic chemistry , quantum mechanics , composite material , chromatography , optics
Compositions of La 1‐ x Ba x CuO 3 , where x ranges from 0.0 to 0.5, were fired in air, oxygen‐enriched air, and oxygen. Studies show that BaO cannot make a solid solution with LaCuO 3 without changing the basic structure. The resulting phases, in all attempts, were the binary compounds La 2 CuO 4 , La 1‐ x Ba x CuO 3‐δ ( x = 0.2 to 0.5), or their mixtures. All samples showed metallic conductivity. Extra oxygen in the reaction atmosphere appeared to encourage the formation of the LaCuO 3 ‐based phases of La 1‐ x Ba x CuO 3‐δ ( x = 0.2 or 0.5). We provide a defect‐chemical and thermodynamical explanation for this observation.