Lattice strain estimation for CoAl2O4 nano particles using Williamson-Hall analysis

CoAl2O4 nanoparticles were prepared via coprecipitation technique through mixing 1:1 M ratio of cobalt nitrate and aluminium nitrate solutions at pH 10. CoAl2O4 crystalline phase was confirmed by X-ray diffraction. Scanning electron microscopy (SEM) result reveals that the particles of CoAl2O4 fired at 900 °C were relatively small (21 nm) and uniform. Increased temperature to 1200 °C gives rise to blocky particles and changes in the powders shape, that because of agglomeration came from the calcination of CoAl2O4. Furthermore, the particle size increase with increasing the calcinated temperature. The crystalline sizes were evaluated by using X-ray peak broadening analysis suggested by Williamson-Hall (W-H) analysis. It was successfully applied for lattice strain and to calculate mechanical stress and energy density values using different three models namely uniform deformation model (UDM), uniform deformation stress model (UDSM) and uniform deformation energy density model (UDEDM). Also, the root mean square strain was determined. These models gave a different strain values which suggested an isotropic nature of the nanoparticles. Besides, the obtained results W-H analysis are in good agreement with that deduced from SEM analysis and Scherrer's formula.