The influence of oxygen variation on the crystal structure and phase composition of the superconductor yttrium barium copper oxide (YBa2Cu3O7-x)

Chemical Synthesis and Properties of Spinel Li1−xCo2O4−δ

“…Lattice parameters and cation distributions were refined by the Rietveld method using the DBWS-9411 PC program (22). The oxidation state of cobalt and the oxygen content were determined by iodometric titration employing KI and sodium thiosulfate solutions (23).…”

Revised Superconducting Phase Diagram of Hole-DopedNax(H3O)zMilne1, Argyriou2, Chemseddine3 et al. 2004Phys. Rev. Lett.

“…Similar methods have been applied to determine the valence of Cu in the cuprates. [6] The fundamental electronic and magnetic interactions in the parent compounds of the superconducting phase are tuned by the doping of 1-x charge carriers on formation of sub-stoichiometric Na x CoO 2 . In the stoichiometric x= 1 compound Co is in the Co 3+ state with S=0 in a low spin (LS) t 6 2g configuration.…”

Studies on the oxygen stoichiometry in superconducting cuprates by thermoanalytical methods

“…The oxygen release and uptake processes are reversible if the heating and cooling cycles are carried out under same atmosphere, as can be seen from the TG curves in Figs la--c [15]. The mass loss of a fully oxidized material starts at about 350~ in both oxygen and nitrogen atmospheres (Figs la and b).…”

“…single crystals) very slow cooling rates or an additional annealing in flowing oxygen at temperatures between 400 and 500~ are required for the complete oxidation. The highest oxygen content achieved for YBazCu3OT_y powders by long annealings in flowing oxygen around 400~ is slightly below (y=0.04 [15]) the stoichiometric value.…”