Thermal decomposition study of cadmium telluride (CdTe)

Abstract

Pure CdTe crystalline material is synthesized at 1073 K temperature in a closed tube under vacuum in horizontal tubular furnace. The synthesized material is found to be stoichiometric having atomic % of Cd: 49.31 and Te: 50.69 as determined by energy dispersive analysis of X-ray. The material is CdTe phase with cubic unit cell structure possessing lattice parameters of a = b = c = 6.48 Å as determined by X-ray diffraction. The morphology of the as-synthesized material is studied by scanning and transmission electron microscopy. The morphology showed clusters of varying sizes ranging from sub-micron to nano having stacked layers. The Raman spectroscopy showed three peaks positioned at 91, 120 and 140 cm−1, corresponding to CdTe. The thermogravimetric, differential thermogravimetric and differential thermal analysis curves of synthesized CdTe are recorded in the temperature range of ambient to 1233 K for three heating rates of 10, 15 and 20 K⋅min−1. The thermocurves demonstrated one-step decomposition of the as-synthesized CdTe material. The thermodynamic parameters, such as activation energy (Ea), activation enthalpy change (ΔH*), Gibb’s free energy change (ΔG*), activation entropy change (ΔS*) and phonon frequency factor (A) are calculated by model-free isoconversional methods. The obtained data and outcomes are discussed thoroughly.