Structural analysis and theoretical investigations in Pb additive Se-Te-Ge chalcogenide nano-composites

In the present study, the impact of lead addition on the structural and physical properties of newly prepared quaternary (Se80Te20)(94-x)Ge6Pbx (x=0, 2, 4, 6, 8 and 10) chalcogenide nano composites has been studied in detail. Nano particle size of each Pb addtive chalcogenide alloy has been deduced using the highest intensity peak of the X-ray diffractograms and it has also been confirmed by field emission scanning electron microscope (FESEM). The detailed study of physical parameters namely average co-ordination number (Z) and number of constraints, lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap has been made. It is observed that Z and constraints have been found to increase with the addition in Pb content. However, all the other investigated parameters viz lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap show a reverse variation. Glass transition temperature has been estimated theoretically using Tichy-Ticha approach and found to be in consonance with the experimental results. The cohesive energy has been calculated using chemical bond approach (CBA) model. Due to lower band gap of Pb, the overall bandgap of the composition has been found to decrease with Pb at.wt.%.