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On the Existence of (O2)2- in YBa2Cu3-yMyO7+x, M=Co and Fe
Published online by Cambridge University Press: 28 February 2011
Abstract
The limiting substitution of Co or Fe for Cu in the orthorhombic superconducting phase YBa2Cu3O7−x yields the tetragonal, semiconducting compositions YBa2Cu2CoO7.25 and YBa2Cu2.5Fe0.5O7.19 after annealing at 400°C and slow-cooling in O2. Single-crystal x-ray structural analyses, conductivity and magnetic-susceptibility measurements, and TGA data provide evidence for Co or Fe substitution at the Cu(1) position and intercalation of peroxide ions (O2)2-. The two compositions decompose for disintercala-tion of oxygen beyond O6.7 for M=Co and O6.4 for M=Fe when heated in N2. The Cu(2) atoms of tetragonal YBa2Cu3O6 appear to be antiferromagnetic below a TN = 240 K, which is similar to comparable Cu-O planar nets in stoichiometric La2LnO4.
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- Copyright © Materials Research Society 1988
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