Structure and microwave dielectric properties of a novel low-firing Ba1−xSrxCo2V2O8 ceramics

Abstract

A low-firing BaCo2V2O8 ceramic was prepared by solid-state reaction and its microwave dielectric properties were reported for the first time. The sample calcined at 700 °C exhibited a low relative dielectric constant (er 16.7) and a high quality factor (Q(u) × f: 73,200 GHz), as well as a poor temperature coefficient of resonator frequency (τf − 41 ppm/°C). In order to obtain a near-zero τf value, Ba1−xSrxCo2V2O8 (x = 0–0.25) ceramics were synthesized by replacing Ba2+ with Sr2+ and the relationship between crystal structure and microwave dielectric properties were studied. The epsilon(r) decreased with the decrease of ionic polarization. The drop in the packing fraction worsened the Q(u) × f values. The varieties in τf values were considered to be closely related to A-site bond valence. Specimen (x = 0.25) fired at 730 °C possess superior microwave dielectric properties: er 14.6, Q(u) × f = 52,120 GHz and τf − 1.6 ppm/°C.