Abstract
Triangular prism-like of crystalline rhombohedral sodium niobate (r-NaNbO3) were prepared from Nb2O5 in the presence of NaOH via a hydrothermal method at 180 degrees C for 6 h. Techniques X-ray diffraction, scanning electron microscopy, Fourier transform infrared, Raman and impedance spectroscopy have been used to characterize the structure, morphology, composition and electrical properties of the material. Electrical conductivity measurements showed that the as synthesized r-NaNbO3 triangular prism has a conductivity value which goes from 5.5 x 10(-6) Omega(-1) cm(-1) at 280 degrees C to 7.61 x 10(-4) Omega(-1) cm(-1) at 780 degrees C. The Arrhenius diagram is not linear; it presents four regions of conductivity. The corresponding activation energies are, respectively, in the order of 0.893, 0.507, 0.819 and 0.105 eV, deduced from the Arrhenius relation. (C) 2012 Elsevier Ltd. All rights reserved.