Wet-chemical synthesis of the potassium niobate nanoparticles powders

Full text: Crystalline lead-free piezoelectric potassium niobate (KNbO₃) powders were successfully synthesized by a new wet-chemical method by means of the dissolution of Nb₂O₅ . 5H₂O and in a solution of oxalic acid followed by the addition of stoichiometric amounts of potassium carbonate. The Nb-K-oxalic acid solution was evaporated resulting in a dry and amorphous powder that was calcined in the temperature range from 400 to 600 °C for 30 minutes. The calcined powders were structurally characterized by X-ray diffraction (XRD) and FT-Raman spectroscopy, and their morphology examined by field emission scanning electron microscopy (FE-SEM). The results showed that pure KNbO₃ powders could be obtained at a temperature of 600 °C and free from the second phases, which was confirmed by a combined analysis using XRD and FT-Raman. The average diameter of the particles was calculated from the HR-SEM image as 70 nm approximately. This technique allows a better mixing of the constituent elements and thus a better reactivity of the mixture to obtain pre-reaction products with high purity at lower temperatures and reducing cost. (author)