17 research outputs found
Vacancy recovery and vacancy-hydrogen interaction in niobium and tantalum studied by positrons
Get PDFPositron-lifetime measurements in electron-irradiated pure Nb and Ta show that monovacancy migration occurs at 220 and 260 K, respectively. Hydrogen impurities can be bound to vacancies, as is experimentally observed in Ta at 70 K after low-temperature α-particle irradiation. The vacancy-hydrogen complex formation shifts the vacancy migration to higher temperatures. Vacancy-hydrogen complexes retain the capability to trap positrons. Theoretical calculations performed for hydrogen and positron states at vacancies are in agreement with experimental findings.Peer reviewe
Vacancy-type defect distributions near argon sputtered Al(110) surface studied by variable-energy positrons and molecular dynamics simulations
No full textColombia 1990-2000: globalización y crisis.
Get PDFEn este ensayo se hace una narrativa del proceso de globalización en Colombia entre los años 1990-2000 para encontrar una explicación sobre la crisis de la economía colombiana. Las políticas liberalizadoras, tanto comerciales como de capitales, conjuntamente con la independencia del Banco de la República fueron el centro de la agenda económica
