Water-Sorption Effects near Grain Boundaries in Modified MgO-Al₂O₃ Ceramics Tested with Positron-Positronium Trapping Algorithm

Water-sorption processes near grain boundaries in the MgO-Al₂O₃ ceramics prepared at different temperatures were studied using positron annihilation lifetime spectroscopy. Numerical values of three- and four-component treatment of spectra were used for study of physical- and chemical-sorption processes in the MgO-Al₂O₃ ceramics. To apply mathematical approach in the form of positron-positronium trapping algorithm into three-component treatment of positron annihilation lifetime spectra it was shown that physical-adsorbed water did not modify positron trapping sites near grain boundaries in water-immersed MgO-Al₂O₃ ceramics and localized mainly in nanopores. The chemically-adsorbed water modifies structural extended defects located near grain boundaries that accompanied them by void fragmentation at water desorption.