Dielectric and structural studies of a SiO2-Li2O-Nb2O5 glass and glass-ceramic prepared by the sol-gel method


The preparation and properties, of nanocrystals embedded in a glass matrix have recently received a considerable amount of interest. The glass composition 92SiO(2)-4Li(2)O-4Nb(2)O(5) (mol%), prepared by the sol-gel route gives origin to a transparent and colorless gel. The dried gel was heat-treated at temperatures between 500 and 750 degrees C, with and without the presence of an external electrical dc field. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Raman and dielectric spectroscopy were used to characterize the glass samples. In the samples heat-treated at 650 degrees C with 1000 kV/m and in the 700 and 750 degrees C samples series, LiNbO3 crystallites, an important ferroelectric material is present. The behavior of the dc conductivity and the dielectric constant, in the glass and glass-ceramic, reflects the important effect of the temperature and the applied electric field on the sample structure. (c) 2005 Elsevier B.V. All rights reserved.




Materials Science


Graca, MPF; da Silva, MGF; Valente, MA

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