Characterization of KNbO3 nanoplates synthesized by a stirred hydrothermal process

Lead free piezoelectric KNbO3 (KN) nanoplates were successfully synthesized through reaction between Nb2O5 and KOH at 220 degrees C and 10 M KOH during 8 h. The influence of stirring hydrothermal process on the morphology was studied. X-ray patterns confirm the formation of a pure compound with a significant increase in lattice parameters relative to the bibliography. FTIR and TG measurements show the presence of hydroxyl groups located at the surface and in the bulk sample. Transmission electron microscopy observation highlights the formation of superimposed plates of KNbO3. The thickness of the plates corresponds to about twenty cells of orthorhombic KN. The measured dielectric constant epsilon(r) and tang delta are 540 and 0.03, respectively at 1 kHz and room temperature. A relaxation phenomenon of domains walls has been observed below 150 K in the losses curves and between 450 and 530 K for the permittivity curves. (C) 2015 Elsevier B.V. All rights reserved.