Changes in the Potential and Vibrational Energies upon the Formation of Vacancies in Oxygen-Doped Cores of Crystallite-Conjugation Regions of Polycrystalline 4d and 5d BCC Transition Metals

摘要

The changes in the potential (u_(cmpl)) and vibrational (epsilon_(cmpl)) energies and the signs of changes in the interatomic spacings (DELTA a_(cmpl)) upon the formation of vacancies in oxygen-alloyed (OA) cores of crystallite-conjugation regions (CCR) in polycrystalline Ad and 5d transition metals Mo, Ta, and W have been determined. The potential energy upon the formation of vacancies (upon the formation of vacancy complexes with oxygen atoms-vacO complexes) in the OA cores of CCRs in polycrystalline Mo, Ta, and W increases (u_(cmpl) are positive), as upon the formation of vacancies in pure CCR cores of transition bcc d metals. The vibrational energy upon the formation of vacancies in OA CCR cores in polycrystalline Mo, Ta, and W decreases (epsilon_(vacO) are negative). The negative sign of changes in the vibrational energy upon the formation of vacancies in the OA CCR cores in Mo, Ta, and W (epsilon_(vacO) < 0) agrees with the independent determinations of the sign of changes in the vibrational energy in the OA CCR cores in polycrystalline tungsten (epsilon_(vacO))w using Mossbauer measurements of the Debye temperature. The signs of changes in the interatomic spacings upon the formation of vacancies in the OA CCR cores in polycrystals of Mo, Ta and W are negative (DELTA a_(vacO) < 0), in contrast to positive (0 < DELTA a_(BCC)) changes in the interatomic distances in the nearest neighborhood of vacancies formed in pure CCR cores in Mo, Ta, and W.