Study of activation energy and thermodynamic parameters of bismuth sulfide by thermogravimetric analysis

Bismuth sulfide chalcogenide was successfully synthesized inside the ampoule by conventional high temperature solid state solvothermal reaction of bismuth and sulfur. It was prepared by adjusting stoichiometric amount of the bismuth and sulfur heated in evacuated sealed quartz ampoule at 850°C for 12h, which is easy to be maintained and controlled. The key step was only adjusting the sulfur content. Synthesized powder was characterized by Energy dispersive Analysis by Energy Dispersive X-ray Spectroscopy (EDXS) and Thermo Gravimetric Analysis (TGA) in an air atmosphere. TGA curves were used to study the decomposition step of the isolated compounds. Activation energy (Eα) for decomposition has been calculated using Broido method. The thermodynamic parameters such as change in enthalpy (ΔH), change in entropy (S) and Gibb's free energy (ΔG) are estimated. TGA analysis shows a remarkable thermal stability with addition of sulfur content.