Probing variation of the structure and electrical conductivity of functionalized PVA based composite films doped with silver nanoparticles and irradiated by gamma rays

Abstract

Polyvinyl alcohol/sulfuric acid/ethanol films doped with nano-silver particles are prepared using in-situ chemical reduction method. The as-prepared films are irradiated with gamma rays at dose range 0–50 kGy. The elemental analysis of as-prepared samples using energy dispersive x-ray spectroscopy (EDXS) showed presence of oxygen and silver peaks which refers to the probable formation of silver oxide nano-particle (Ag2O NPs) phase. Moreover, scanning electron microscope (SEM) analysis confirmed that the inserted Ag nanoparticles have regular and uniformly distributed pores within the PVA network. X-ray diffraction (XRD) measurements indicated that of Ag2O and Ag nanoparticles are embedded in the PVA matrix in cubic face-centered structure. Structural variations due to gamma irradiation are also probed by high-resolution transmission electron microscopy (HR-TEM) which displayed that the diameter of encapsulated Ag nanoparticles increases from ∼15 nm up to 34 nm against irradiation dose. The measured dc electrical conductivity results indicated that the thermal activation energy decreased from 0.95 eV to 0.56 eV as a sequence of irradiation dose in the range 0–50 kGy The evaluation of the frequency exponent factor, s, derived from the measured ac conductivity data indicated that correlated barrier hopping (CBH) is the most probable conduction mechanism for the present films. The measured dielectric constants and Cole-Cole diagrams are employed in the analysis of the dependence of the dielectric constant on the irradiation dose.