Microstructural and defects characteristics of xV2O5–(1-x)(0.35MoO3–0.65ZnO) glass nanocomposites utilizing positron annihilation spectroscopy and correlated experimental methods

Abstract

One binary and a few ternary glass nanocomposite systems of the general composition formula xV2O5–(1-x)(0.35MoO3–0.65ZnO), where x varied from 0.0 to 0.95, were prepared via the melt quenching technique and characterized through Transmission electron microscopy and X-ray diffraction method. Positron annihilation lifetime and coincidence Doppler broadening spectroscopy techniques were also utilized to detect various types of defects formed within the samples. The patterns of the X-ray diffraction method revealed distinct diffraction peaks specifying the formation of nanocrystallites in x = 0.0, 0.15 and 0.35 samples.While for x = 0.55, 0.75 and 0.95 samples, significantly broadened patterns were observed, indicating predominant amorphous characteristics. Different shapes and sizes of so-formed nanocrystallites were also confirmed and measured by Transmission electron microscopy images. Moreover, selected area electron diffraction patterns revealed a few bright spots superimposed over diffuse rings, specifying the presence of nanocrystallites over the amorphous glass matrix. Positron annihilation lifetime measurements for x = 0.0, 0.15, and 0.35 samples revealed that positrons were trapped in the intermediate gaps around the nanocrystallites and vacancy types of defects. Positrons were trapped within the porous type defects inside the amorphous glass matrix and in vacancy clusters for x = 0.55, 0.75, and 0.95 samples. Further, coincidence Doppler broadening studies established the formation of vacancy types of defects due to cation non-stoichiometry and amorphousness of the glass nanocomposites.