Physical & Chemical Water-sorption Processes in the MgAl2O4 Ceramics

Structural properties and physical and chemical water-sorption processes were investigated in the humidity-sensitive MgAl
2
O
4
ceramics sintered at 1300 °C for 2 h under the influence of water. It is shown that ceramics has developed the structure of grains, grain boundaries and pores with trimodal pore size distribution. It is established that absorbed water in ceramics result in more intensive trapping of positrons in extended defects near grain boundaries. Furthermore, the presence of water in the inner structure of ceramics leads to specific fragmentation of free volume in the nanopores and ortho-positronium decaying in the water.