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Defect chemistry of La[sub 2-x]Sr[sub x]CuO[sub 4-x/2](O < x [le] 1)

Journal Article · · Journal of Solid State Chemistry; (United States)
;  [1]
  1. Lehigh Univ., Bethlehem, PA (United States)
The hole concentration in oxygen-equilibrated La[sub 2-x]Sr[sub x]CuO[sub 4-x/2] increases linearly with x up to x [approx] 0.15, passes through a maximum value, and then decreases for further increases in x. This change in behavior is attributed to a shift in the charge-compensating defect from holes to oxygen vacancies. However, classical defect chemistry indicates that the hole concentration should only shift to a less rapid rate of increase with x, but not decrease. The observed decrease is caused by an increase in the enthalpy of the oxidation reaction that fills vacancies and replaces them with holes. This occurs because large concentrations of oxygen vacancies are effective in relieving imbalances in stress and charge that exist in the intergrowth structure of La[sub 2]CuO[sub 4]. As a result, the vacancies become increasingly favored over holes as the charge compensating defect in the highly acceptor-doped material. The increase in the enthalpy of oxidation results in maximum values for both the hole concentration and [Tc] as functions of the acceptor content.
OSTI ID:
7079125
Journal Information:
Journal of Solid State Chemistry; (United States), Journal Name: Journal of Solid State Chemistry; (United States) Vol. 102:1; ISSN 0022-4596; ISSN JSSCBI
Country of Publication:
United States
Language:
English