Ortho-Positronium “Pick-off” Annihilation Processes in Nanoporous MgAl2O4 Ceramics for Sensor Electronics

Humidity-sensitive nanoporous MgAl2O4 ceramics prepared at 1200, 1300, 1400 and 1400 °C for sensor electronics were investigated using positron annihilation lifetime spectroscopy tools. The annihilation spectra obtained by decomposition into four components were analyzed. The third and fourth components reflect the ortho-positronium decay in nanopores. It is shown that at lower sintering temperature ceramics contain more nanopores. The processes of “Pick-off” annihilation of ortho-positronium in MgAl2O4 ceramics were simulated and the sizes of nanopores in different approximations were defined. The sizes of nanopores (radius in spherical approximations) were obtained within Tao-Eldrup model using lifetimes of ortho-positronium decay. It is established that used model can be adequate applied to describing “pick-off” annihilation processes in nanopores of ceramic materials for humidity sensors.