Effect of Rare-Earth Doping on Free-Volume Nanostructure of Ga-Codoped Glassy (As/Sb)(2)Se(3)

Subsequent stages of atomic-deficient nanostructurization finalizing rare-earth functionality under Pr(3+)-doping in Ga(2)(As(0.28)Sb(0.12)Se(0.60))(98) glass are studied employing method of positron annihilation lifetime spectroscopy. Genesis of free-volume positron trapping sites, composed of atomic-accessible geometrical holes (void cores) arrested by surrounding atomic-inaccessible Se-based bond-free solid angles (void shells), are disclosed for parent As(2)Se(3), Ga-codoped Ga(2)(As(0.40)Se(0.60))(98), as well as Ga-codoped and Sb-modified Ga(2)(As(0.28)Sb(0.12)Se(0.60))(98) glasses. The finalizing nanostructurization due to Pr(3+)-doping (500 wppm) in glassy Ga(2)(As(0.28)Sb(0.12)Se(0.60))(98) is explained in terms of competitive contribution of changed occupancy sites available for both rare-earth ions and positrons.