Structural and optical properties of KNN nanocubes synthesized by a green route using gelatin

Sodium potassium niobate nanoparticles [(K0.5Na0.5)NbO3, KNN], KNN-NPs, were synthesized using a modified sol-gel method. Structural and optical properties of the prepared samples were investigated by thermogravometric analyzer (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-Vis spectroscopy. The XRD patterns showed that the formation of the orthorhombic KNN-NPs starts at 500 degrees C calcination temperature. Raman spectroscopy was used to investigate the crystalline symmetry and the structural deformation of the prepared KNN-NPs. TEM images showed that the morphology of the prepared particles is cubic, with the average size of about 50 nm. From diffused reflectance spectroscopy along with using Kubelka-Munk method, the energy bandgaps were determined to be indirect with the values of 3.13 eV and 3.19 eV for the samples calcined at 500 degrees C and 600 degrees C, respectively.