Positron Annihilation in Pure and Hydrogenated Palladium Deformed by Uniaxial Tension

Angular distributions of the positron annihilation quanta were measured for pure and hydrogenated palladium samples deformed by uniaxial tension up to different deformation degrees. The relative difference curves, and the values of the R parameter characterizing the dimensions of defects trapping the positrons, were determined. It was found that for relative elongations ranging from 1.9 to 3.5%, in both the pure and hydrogenated palladium, the positrons are trapped in defects larger than vacancy clusters. The values of the R parameter for pure palladium samples elongated up to 0.39, 0.77, and 1.5% indicate a dominant role of smaller defects, like the vacancy clusters.