Phase transformation and thermal stability studies of Fe-doped ZnSe nanocrystals

This study explored the phase transformation in ZnSe doped with Fe ions via XRD, TGA, and HRTEM analyses. The X-ray diffraction pattern of the Fe-doped ZnSe nanocrystal milled for 5 hours, 10 hours, and 20 hours revealed a cubic phase structure that became progressively stable after 5 hours of milling. The XRD peaks broadened with increasing milling time, suggesting a decrease in the crystallite size of 4.2 nm after 20 h of milling, as evaluated by Scherre’s formula. High-resolution transmission electron microscopy (HR-TEM) revealed well-defined lattice fringes with an interplanar spacing of approximately 0.38 nm. The thermal properties of the milled powder were characterized via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The endothermic peak increases linearly from 230–475 °C, whereas the exothermic peak decreases and later increases with increasing milling time. The thermal stability of the Fe-doped ZnSe nanocrystal improved as the milling progressed, and a weight loss of 14–4% was recorded.