Positron annihilation exploration of voids in zinc zirconium borate glass ceramics entrenched with ZnZrO3 perovskite crystal phases

Abstract

Origin of atomic-deficient free-volume structure in ZnO–ZrO2–B2O3 glass ceramic versus ZrO2 concentration was explored by positron annihilation lifetime spectroscopy (PAL) technique. XRD and SEM studies, on the titled samples indicated that the samples consist of tetragonal ZnZrO3 perovskite crystal phases. The IR spectroscopic studies suggested that Zr4+ ions prevailingly occupy octahedral positrons and play crucial role in formation of positron trapping holes in the samples. The PAL studies using 0.1MBq 22Na positron source indicated a significant variation in the positron annihilation life time with increasing ZrO2 for both positron- and positronium (Ps) trapping channels. The intensity of the longest positron annihilation component I3 is decreased from 4.45 to 3.07%, whereas o-Ps decay lifetime τ3 is enhanced from 1.18 to 1.34ns with increase of ZrO2 from 0 to 5.0mol%. These results suggested that the glass ceramic CZ5 contains the maximum free space or void expansion and void agglomeration.