Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal–Hydrogen Systems

Abstract

The current work is devoted to developing a system for the complex research of metal–hydrogen systems, including in an in situ mode. The system consists of a controlled gas reactor with a unique reaction chamber, a radioisotope positron source, and a positron annihilation spectroscopy complex. The use of the system enables in situ investigation of the defect structure of solids in hydrogen sorption–desorption processes at temperatures up to 900 °C and pressures up to 50 bar. Experimental investigations of magnesium and magnesium hydride during thermal annealing were carried out to approve the possibilities of the developed complex. It was shown that one cycle of magnesium hydrogenation–dehydrogenation resulted in the accumulation of irreversible hydrogen-induced defects. The defect structure investigation of the magnesium–hydrogen system by positron annihilation techniques was supplemented with a comprehensive study by scanning electron microscopy, X-ray diffraction analysis, and hydrogen sorption–desorption studies.

Crystal Structure Defects in Titanium Nickelide after Abc Pressing at Lowered Temperature

“…To analyze structural defects by positron spectroscopy, we used a hybrid digital positron spectroscopy complex with an external synchronization system based on positron annihilation lifetime spectrometry (PALS) modules and coincidences Doppler broadening spectroscopy (CDBS) [56]. The time resolution of the PALS module is 172 ± 6 ps, and the count rate is 110 ± 30 counts/s.…”