The microwave dielectric properties of the (1 - x)(Mg0.95Mn0.05)TiO3-xCaTiO3 ceramic system prepared by mixed oxide route have been investigated. The microstructures of the ceramics were characterized by SEM. Ilmenite-structured (Mg0.95Mn0.05)TiO3 and perovskite-structured CaTiO3 were coexisted and the two-phase system was confirmed by the XRD and EDX analysis. The microwave dielectric properties are strongly related to the density and matrix of the specimen. Combination of (Mg0.95Mn0.05)TiO3 and CaTiO3 forms a two-phase system and leads to a near-zero τf. With increasing x, the microwave Q × f decreased and εr increased. A new microwave dielectric material, 0.93(Mg0.95Mn0.05)TiO3-0.07CaTiO3 possesses excellent microwave dielectric properties with a dielectric constant (εr) of ∼22.67, a Q × f of ∼90,700 GHz (where f = 9 GHz, is the resonant frequency) and a τf value of ∼0.8 ppm/°C at 1270 °C for 4 h. It is proposed as a suitable material candidate for applications requiring low microwave dielectric loss.
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