Effect of solvent and temperature on the preparation of potassium niobate by hydrothermal-assisted sol–gel processing

• Published in: Ceramics international 2009-08, Vol.35 (6), p.2367-2372
• Main Authors: Amini, Mostafa M., Mirzaee, Mehdi
• Format: Article
• Language: English
• Subjects: B. X-ray method; D. Niobate; D. Perovskite; Hydrothermal; Sol–gel
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2009.01.009

In this study the preparation of potassium niobate powder, a material with high electro-optic and nonlinear optical coefficients, by hydrothermal-assisted sol–gel processing from potassium-niobium ethoxide [KNb(OC 2H 5) 6] have been performed. The development of potassium niobate phases by hydrothermal hydrolysis of potassium niobium ethoxide at 100 and 200 °C in ethanol, toluene, and a mixture of benzene and ethanol was pursued by X-ray diffraction. Selected powders obtained from hydrothermal-assisted sol–gel processing were characterized by X-ray powder diffraction, thermal analysis (TGA/DSC), and scanning electron microscopy (SEM). X-ray diffraction results showed that the hydrothermal hydrolysis of potassium-niobium ethoxide in ethanol at 100 and 200 °C results in the formation of cubic phase KNbO 3. Hydrolysis in a mixture of benzene/ethanol and toluene at 200 °C produces an orthorhombic phase KNbO 3, which is a mixture of the potassium deficient phase, K 4Nb 6O 17, and cubic and orthorhombic KNbO 3 phases. The potassium niobate powder prepared by the hydrothermal method had the advantage of low weight loss during calcination. SEM micrographs showed that the shape of particles prepared by hydrothermal-assisted sol–gel processing is more uniform when compared with the sample prepared by conventional sol–gel processing.