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Internal chemistry of the pure and chemically substituted quadruple perovskites Ln{prime}Ln{double_prime}Ba{sub 2}Cu{sub 2}Ti{sub 2}O{sub 11} (Ln{prime}Ln{double_prime} = LaY or NdDy)

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/ja963908r· OSTI ID:512907
; ; ; ;  [1];  [2]
  1. Northwestern Univ., Evanston, IL (United States)
  2. Northern Illinois Univ., DeKalb, IL (United States)
The Ln{prime}Ln{double_prime}Ba{sub 2}Cu{sub 2}Ti{sub 2}O{sub 11} materials, with their unique A-site ordering and reduced bond lengths, are very attractive candidates for superconductivity. This paper reports specific variations in the inner architecture to achieve appropriate carrier concentration and in-situ thermopower and conductivity studies. Both nominally undoped materials, with the stoichiometries Ln{prime}Ln{double_prime}Ba{sub 2} Cu{sub 2}Ti{sub 2}O{sub 11} (Ln{prime}Ln{double_prime} = LaY and NdDy), and chemically substituted derivatives, NdDyBa{sub 2-x}Sr{sub x}Cu{sub 2+y} Ti{sub 2-y}O{sub 11} and La{sub 1+x}YBa{sub 2-x}Cu{sub 2+y} Ti{sub 2-y}O{sub 11}, were investigated using equilibrium high-temperature electrical property measurements. The solid solution limits and the effect of high oxygen pressure treatments were investigated. The normal state conductivity and thermopower are reported as a function of oxygen partial pressure, temperature, and composition, and Jonker analyses are used to make comparisons to known superconductors. The electrical property measurements are used to elucidate the internal chemistry of these complex solid state materials. 34 refs., 8 figs.
OSTI ID:
512907
Journal Information:
Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 16 Vol. 119; ISSN JACSAT; ISSN 0002-7863
Country of Publication:
United States
Language:
English