Vacancy recovery and vacancy-hydrogen interaction in niobium and tantalum studied by positrons
نویسندگان
چکیده
منابع مشابه
First principles study of oxygen vacancy defects in tantalum pentoxide
First principles total energy calculations were performed to characterize oxygen vacancy defects in tantalum pentoxide (Ta2O5). A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancy that occupies the ‘‘in-plane’’ sites displays de...
متن کاملFirst principles study of oxygen vacancy migration in tantalum pentoxide
First principles total energy calculations were performed in order to determine oxygen vacancy migration energies in Ta2O5 . A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. O vacancies in the chosen model of Ta2O5 can be broadly classified into ‘cap’ and ‘in-plane’ sites based on their location in the lattice. The cap type of vacancies display the lar...
متن کاملVacancy Formation Energy at High Pressures in Tantalum
We have computed the variation of the vacancy formation energy with pressure for Ta. Total energy calculations were performed for 16 and 54 atom supercells using a mixed basis pseudopotential method which uses pseudoatomic orbitals and low energy plane waves as the basis set, within density functional theory (LDA and GGA). The vacancy formation energy is found to increase from 2.95 eV at ambien...
متن کاملVacancy formation enthalpy at high pressures in tantalum
Using a mixed basis pseudopotential method, total energy calculations were performed to obtain the enthalpy of vacancy formation in Ta as a function of pressure, which is important for understanding the effects of pressure on mechanical properties. The vacancy formation enthalpy is found to increase from 2.95 eV at ambient pressures to 12.86 eV at 300 GPa, and the vacancy formation volume decre...
متن کاملHydrogen-vacancy interactions in Fe-C alloys.
Energetics and concentrations of hydrogen-containing point defect clusters (PDCs) in Fe-C alloys are calculated and cast into a PDC dominance diagram. Because of the strong binding effects of iron vacancies on the stability of the clusters, hydrogen accumulation requires the total hydrogen and vacancy concentrations to be comparable. As a result of the interplay between repulsive and attractive...
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ژورنال
عنوان ژورنال: Physical Review B
سال: 1985
ISSN: 0163-1829
DOI: 10.1103/physrevb.32.4326