Concentration-dependent oxygen diffusivity in YBa2Cu3O6+x: II. Oxygen partial pressure studies

✍ Scribed by John R. LaGraff; David A. Payne

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 555 KB
• Volume: 212
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90617-y

✦ Synopsis

Electrical resistance measurements were used to determine the equilibrium resistiviD characteristics and the oxygen diffusion behavior in YBa2Cu30~,+ ~ ( YBCO ) as a function of oxygen partial pressure at lcmpcratures ranging fl'om 450-850 ('. The equilibrium resistivity values depended on the oxygen partial pressures as ~= iiLogp/hLog[ I'(O~) ], ~here n ranged fi-om approxi mately -1 up to -½ from low to high temperatures. A clcar p-type to n-typc transition was obserx ed near 750 C tk)r an oxygen content of 6.1 (x=0.1). Values ofthe oxygen exponent, n, for singlc crystal YB('O at 650 (' and 708 : (" were similar to thosc for polycrystalline specimens. Measurements of the time-dependent resistivity behavior bctwccn different oxygen partial pressures yielded diffusion kinetics between well-established boundaD' values of the oxygen content. *. In single crystal specimens, lhe chemical diffusivity for oxygen in-diffusion was observed to increase with decreasing oxygen conlent. The kinetic data for the polycrystalline specimens between 450-850: C also depended on the ox}gcn conccntrat ion: howe~ cr. lht temperature dependence was non-Arrhenius.