Regions of Enhanced Concentration of Point Defects Localized near Internal Interfaces in Condensed Media: III. Composition and Structure of Vacancy-Oxygen Complexes in Regions of Enhanced Concentration of Point Defects in Pd, Ta, W, and Pt

摘要

The results of investigations of point defects located in the immediate vicinity of atomic probes ~(57)Co localized outside the cores of crystallite-conjugation regions (CCR) in nominally pure polycrystalline metals Pd, Ta, W, and Pt are discussed. In lattice regions with dimensions of about 1 nm in the direction perpendicular to the surface of CCRs with an enhanced concentration of point defects (RECPDs), the "natural" solid-solution-forming impurity is oxygen. Temperature dependences of isomeric shifts and widths of volume components of Mossbauer spectra were used to obtain information on the composition and structure of complexes that arise in RECPDs upon isochronous vacuum annealings of nominally pure metals. In the RECPDs of the systems under consideration, oxygen-vacancy complexes are formed. The structural characteristics of these complexes were determined, namely, the magnitude of the negative change in the volume of the RECPD upon the formation of such complexes, the relationship between the number of oxygen atoms and vacancies in a complex, the effect of the oxygen-vacancy complexes and oxygen impurities in the solid solution on the width of the Mossbauer lines.