Synthesis of homogeneous (Na1-xKx)NbO3 nanorods using hydrothermal and post-heat treatment processes

Abstract

To synthesize (Na1-xKx)NbO3 nanorods, the Nb2O5-added (1 - y)NaOH-yKOH specimens with 0.0 <= y <= 0.9 were heated at 160 degrees C and subsequently annealed at 500 degrees C. Homogeneous Na-rich (Na1-xKx)NbO3 nanorods were only synthesized for the specimen with y = 0.15. However, NaNbO3 nanorods were formed for specimens with y < 0.15, and K-rich (Na1-xKx)NbO3 nanoplates were obtained for specimens with y > 0.2. The (Na8xK8-8x)Nb6O19 center dot nH(2)O transient phase was formed in the specimen with y = 0.15 heated at 160 degrees C for 8.0-12.0 h, and this phase transformed into the Na-rich (Na1-xKx)NbO3 nanorods after annealing at 500 degrees C. Therefore, the formation of a homogeneous (Na8xK8-8x)Nb6O19 center dot nH(2)O phase at a low temperature is very important for the synthesis of the (Na1-xKx)NbO3 nanorods. The (Na8xK8-8x)Nb6O19 center dot nH(2)O phase was considerably influenced by the heating temperature, and the processing time. The Na-rich (Na1-xKx)NbO3 nanorods have rectangular shape with various sizes, and the growth direction of these nanorods is [001]. (C) 2012 Elsevier B.V. All rights reserved.