High dielectric constant and high-Q in microwave ceramics of SrTiO3 co-doped with aluminum and niobium

Al/Nb co-doped SrTiO3 microwave ceramics with the composition of SrTi1-x(Al0.5Nb0.5)(x)O-3 (x = 0.03, 0.05, 0.1, and 0.15) have been synthesized via a standard solid-state reaction method. The substitution of (Al0.5Nb0.5)(4+) in B-site inhibits the reduction in Ti4+ ions and the growth of grain size, then the transport of mobile charge carriers is limited, and thus the Q value is improved. For the SrTi0.9(Al0.5Nb0.5)(0.1)O-3 ceramics, in addition to their high dielectric constant (epsilon(r) similar to 185), they exhibit correspondingly a high Qf value (similar to 9077 GHz) at 2.9 GHz, making the microwave ceramics suitable for myriad device miniaturization and high-performance wireless communication.