Evaluation of kinetic data for crystallization of Mn–Fe co-doped ZnO nanoparticles synthesized via sol–gel process

Abstract

Crystallization kinetics of metal oxides is an exciting subject because it directly relates to the structure and property of the metal oxides. Recently, doping ZnO by transition metals shown advantageous in the modification of the morphology of ZnO in photocatalytic applications as well as other specific applications. In the current research, Mn–Fe co-doped ZnO nano-powders synthesized via the Pechini sol–gel process. Through differential scanning calorimetry (DSC), X-ray diffraction (XRD), High-Resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), and selected area electron diffraction (SAED) the crystallization kinetics, growth mechanism; morphological as well as the structural characteristics of the Mn–Fe co-doped ZnO dry gels studied, respectively. The XRD and SAED results revealed that the dry gels calcined at 800 °C for 2 h have a wurtzite symmetry. By a non-isothermal DSC technique, the crystallization activation energy for wurtzite Mn–Fe co-doped ZnO calculated ~308.19 kJ/mol. Bulk nucleation was dominant in the wurtzite Mn–Fe co-doped ZnO crystallization; since the crystallization growth mechanism index (m) and morphology parameter (n) were close to 3.0. Wurtzite Mn–Fe co-doped ZnO powders had a semispherical morphology with a primary particle size from 20 to 30 nm using the electron microscopy examination.