52 research outputs found
Vacancy recovery and vacancy-hydrogen interaction in niobium and tantalum studied by positrons
Positron-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
Health Monitoring and Performance Life Remaining Determination for Aircraft Structural Components
Nondestructive Aging and Cross-Link Density Damage Detection in Solid Rocket Fuel Propellant
Nondestructive In-Situ Examination of Solid Rocket Motor Propellant Using Induced Positron Technology
Point Defects in Undoped Semi-insulating GaAs: Correlation Between thermally Stimulated Current and Positron Annihilation Spectroscopies
Point defects and the main electron traps in undoped semi-insulating GaAs grown by vertical gradient freeze and high- and low-pressure liquid encapsulated Czochralski techniques have been studied by positron annihilation (PAS) and thermally stimulated current (TSC) spectroscopies, respectively. We find good correlations between the concentrations of the TSC traps T-2 (0.63 eV) and T-5 (0.35 eV), and the PAS identified-defects As-Ga, and V-As, respectively. A good correlation between the concentration of intrinsic accepters (V-Ga and Ga-As) measured by PAS, and the total acceptor concentration measured by infrared absorption, is also found
Point Defects in Undoped Semi-insulating GaAs: Correlation Between thermally Stimulated Current and Positron Annihilation Spectroscopies
Point defects and the main electron traps in undoped semi-insulating GaAs grown by vertical gradient freeze and high- and low-pressure liquid encapsulated Czochralski techniques have been studied by positron annihilation (PAS) and thermally stimulated current (TSC) spectroscopies, respectively. We find good correlations between the concentrations of the TSC traps T-2 (0.63 eV) and T-5 (0.35 eV), and the PAS identified-defects As-Ga, and V-As, respectively. A good correlation between the concentration of intrinsic accepters (V-Ga and Ga-As) measured by PAS, and the total acceptor concentration measured by infrared absorption, is also found
Effect of Porosity on the Mean Lifetime of Positrons in Sintered and Hot-Pressed alpha-Alumina
Microscopic Nature of Thermally Stimulated Current and Electrical Compensation in Semi-Insulating GaAs
Evidence of 2 Kinds of Acceptors In Undoped Semiinsulating Gaas - Positron Trapping At Gallium Vacancies and Negative-ions
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