Structural and microwave dielectric properties of the (1-x) Li3NbO4-x Ca0.8Sr0.2TiO3 thermally stable ceramics

The ceramic system of (1-x) Li3NbO4-x Ca0.8Sr0.2TiO3 prepared by solid reaction route has been found to possess excellent dielectric properties. Li3NbO4 was combined with Ca0.8Sr0.2TiO3 to obtain a two-phase ceramic system and to achieve a thermally stable material. As x value varied from 0.1 to 0.4, the temperature coefficient of resonate frequency values (tau(f)) ranged from +119.1 ppm/degrees C to -30.7 ppm/degrees C. At x = 0.2, the 0.8 Li3NbO4-0.2 Ca0.8Sr0.2TiO3 ceramic sintered at 1075 degrees C for 4 h exhibited outstanding microwave dielectric properties with a relative dielectric constant (epsilon(r)) similar to 21.7, a quality factor (Q x f) value similar to 49,276 GHz (at 6.1 GHz), and tau(f)similar to 5.2 ppm/degrees C, which represented a promising candidate for microwave dielectric applications. Moreover, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were included in our work to help identify and analyze the phase assemblage and the microstructure of the sintered ceramics. (C) 2015 Elsevier B.V. All rights reserved.