Correlation between the Dynamics of Oxygen Atoms and Oxidation Kinetics of Solid Solutions Based on Bi_2Sr_2CaCu_2O_8

摘要

The oxidation kinetics of Bi_(1.3)Pb_(0.8)Sr_2Ca_(0.8)Y_(0.2)Cu_2O_8 + solid solutions at different temperatures and pO_2 = 0.21 atm is investigated by thermogravimetry. The results obtained are compared with the previously studied oxidation kinetics of Bi_(1.5)Pb_(0.6)Sr_2CaCu_2O_8 + solid solutions. It is found that the substitution of yttrium for calcium leads to an appreciable retardation of the initial oxidation stage associated with the oxygen diffusion. The phonon spectra of the solid solutions are examined using inelastic neutron scattering on a DIN-2PI direct-geometry spectrometer. The high-frequency (>50 meV) phonon densities of states for yttrium-containing and yttrium-free solid solutions are analyzed. The possible model is proposed for a correlation between the differences observed in the high-frequency phonon densities of states attributed to the vibrations of oxygen atoms and the differences in the oxidation kinetics of the solid solutions under consideration.