Nonlinear resistivity in fully oxygenated YBa2Cu3O7−δ Frenkel disorder of chain oxygens

✍ Scribed by Dan Goldschmidt; Yakov Eckstein

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 510 KB
• Volume: 200
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(92)90325-7

✦ Synopsis

Fully oxygenated ceramic YBa2Cu307_6 has a non-linear resistivity [p (T) ] reminiscent of the resistivity Pb (along chains) in untwinned single crystals. The excess resistivity above 200 K, measured with respect to the linear portion of p(T) is activated. We suggest a Frenkel-disorder process, in which a chain oxygen jumps from its O( 1 ) chain site to the nearby 0(5 ) site, to account for the excess electron scattering. The activation energy, which represents the difference in energy between both sites, is ~ 120 meV for ceramics, thin films and single crystals, in agreement with the activation of the orthorhombic to tetragonal transition. The characteristic defect resistivity is ~ 2 mr2 cm, close to the minimum metallic conductivity, perhaps implying strong disorder. Our model supports the view that chains and planes make separate contributions to normal-state conductivity.