Positron annihilation characterization of free volume in micro- and macro-modified Cu₀.₄Co₀.₄Ni₀.₄Mn₁.₈O₄ ceramics

Abstract

Free volume and pore size distribution size in functional micro and macro-micro-modified Cu₀.₄Co₀.₄Ni₀.₄Mn₁.₈O₄ ceramics are characterized by positron annihilation lifetime spectroscopy in comparison with Hg-porosimetry and scanning electron microscopy technique. Positron annihilation results are interpreted in terms of model implication positron trapping and ortho-positronium decaying. It is shown that free volume of positron traps are the same type for macro and micro modified Cu₀.₄Co₀.₄Ni₀.₄Mn₁.₈O₄ ceramics. Classic Tao-Eldrup model in spherical approximation is used to calculation of the size of nanopores smaller than 2 nm using the ortho-positronium lifetime.