Characterization of YBa₂Cu₄O₈ high temperature electrical properties and thermodynamic stability

Abstract

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500-800 °C and oxygen partial pressure range 1 0~4 -l atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu408 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu306+j/ (or YBa2Cu3.5O7.5±z) and CuO occurs at Iog(po2,atm) = -1.24 x 104/T(K) + 11.01(773 < T(K) ^ 1073).

Transmission Electron Miscroscopy Observation of the Decomposition of YBa2Cu4O8 into YBa2Cu3O7-δ and CuO

“…10 210 -6 ? 10 211 bar within the TEM, from stability investigations of Morris et al 11 and Hong and Mason, 12 the decomposition temperatures are estimated to be 482 -455 ± C or 317-289 ± C, respectively. (It has to be pointed out that this is really a very rough estimation because the literature data for T U which have been determined for oxygen partial pressures between 1 bar and 10 24 bar were extrapolated to p͑O 2 ͒ values which are several orders lower.)…”