Microwave dielectric properties of low-fired Ba5Nb4O15

Abstract

The effect of B2O3 on the sintering temperature and microwave dielectric properties of Ba5Nb4O15 has been investigated using X-ray powder diffraction, scanning electron microscopy, and a network analyzer. Interactions between Ba5Nb4O15 and B2O3 led to formation of second phases, BaNb2O6 and BaB2O4. The addition of B2O3 to Ba5Nb4O15 resulted in lowering the sintering temperature from 1400° to 925°C. Low-fired Ba5Nb4O15 could be interpreted by measuring changes in the quality factor (Q × f), the relative dielectric constant (εr), and the temperature coefficient of resonant frequency (τf) as a function of B2O3 additions. More importantly, the formation of BaNb2O6 provided temperature compensation. The microwave dielectric properties of low-fired Ba5Nb4O15 had good dielectric properties: Q × f = 18700 GHz, εr = 39, and τf = 0 ppm/°C.