Modified Positron Annihilation Lifetime Spectroscopy Method for Investigation of Nanomaterials with Advanced Porosity

Modified method for measuring of positron annihilation spectra on the example of humidity-sensitive MgO-Al
₂
O
₃
ceramics with advanced nanoporousity is proposed. It is shown that in the expansion of spectra into four components it is possible to estimate the nanopor sizes and to study the processes occurring in them. It was established that the nanoparticle fraction with a radius of ~ 1.5 nm is an order of magnitude higher than the proportion of pores with a radius of ~ 0.3 nm, in which also the ortho-positronium annihilation in adsorbed water occurs.