High permittivity and low loss ceramics in the BaO-SrO-Nb2O5 system

A new group of compounds with composition (Ba55 − xSrx)Nb4O15, having high permittivity and low loss have been prepared and characterised in the microwave frequency region. X-ray diffraction studies showed that monophase compound existed for all values of x from 0 to 5. Microwave dielectric properties such as εr and τf showed smooth variation with x, while the unloaded quality factor (Qu) showed remarkable improvement with x. A range of ceramic dielectric resonators(DR) with 40 < εr < 50, −10 < τf < +10 and Q × f >10,000 can be obtained in this system.