December 13, 2019
Dariush Souri

Dariush Souri

Academic rank: Associate professor
Address:
Education: Ph.D in فیزیک
Phone:
Faculty: science

Research

Title Growth of silver nanoparticles within the tellurovanadate amorphous matrix: Optical band gap and band tailing properties, beside the Williamson- Hall estimation of crystallite size and lattice strain
Type Article
Keywords
Keywords: Glass-ceramics Energy band gap Williamson-Hall approach Urbach energy DASF method
Journal CERAMICS INTERNATIONAL
Researchers Dariush Souri

Abstract

The present paper aims at growth of silver nanoparticles in the tellurovanadate glassy matrix, structural verification including determination of the size of nano-crystals and lattice strain using Williamson-Hall approach, evaluation of energy band gap and the width of the localized states (Urbach energy) and comparison of the obtained results with the previously reported data for corresponding glasses. So, the bulk and blown-layer glasssystems of xAg2O-40TeO2-(60-x)V2O5 compositions with different molar concentrations (0≤x≤50), were converted to glass-ceramics using heat treatment. To investigate the optical properties, optical absorption spectra of layer samples were recorded within the wavelength range of 190–1100 nm. So, the energy band gap and the width of the localized states (Urbach energy) were determined using the high precision derivation of absorption spectrum fitting (DASF) method, and the obtained results show the major increase compared with those corresponding glasses, implying on the formation of nano-crystals in glassy matrix (glass-ceramics). The Williamson-Hall method was used to determine the size of nano-crystals and lattice strain. Among the samples, sample with x=40 has the lowest lattice strain (with high elastic moduli, promising it as coating materials) and sample with x=30 has the lowest size in nano-phase. It was found that, in spite the outputs of Scherrer̛ s formula, the results of the crystallite size measured by Williamson-Hall method were in good agreement with FESEM results; such results confirm the validity of Williamson-Hall approach for X-ray peak variance analysis.