High dielectric constant and low-loss dielectric ceramics of Ba5LnZnNb9O30 (Ln = La, Nd and Sm)

Polycrystalline Ba(5)LnZnNb(9)O(30) (Ln=La, Nd and Sm) ceramics were prepared as single-phase materials through conventional solid-state ceramics route. The structure was characterized by X-ray diffraction methods and scanning electron microscopy (SEM) and the dielectric properties were measured from - 120 degrees C to 150 degrees C. All three compounds are paraelectric phases adopting the filled tetragonal tungsten-bronze (TB) structure at room temperature, and the Curie temperature (at 1 MHz) were -60, -25 and -5 degrees C for Ba5LaZnNb9O30, Ba5NdZnNb9O30, and Ba5SmZnNb9O30 respectively. At 1 MHz their dielectric constant (epsilon(r)) varies from 258 to 310, dielectric loss (tan delta) from 0.0033 to 0.0068, and the temperature coefficients of the dielectric constant (tau(epsilon)) from - 1220 to - 1390 ppm degrees C-1. (c) 2007 Elsevier B.V. All rights reserved.