High dielectric constant low loss in the (La1/2Na1/2)TiO3-Ca(Mg1/3Nb2/3)O3 ceramic system at microwave frequency

The crystal structures and microwave dielectric properties of the x(La1/2Na1/2)TiO3-(1 − x)Ca(Mg1/3Nb2/3)O3 perovskite ceramic system were investigated. The x(La1/2Na1/2)TiO3-(1 − x)Ca(Mg1/3Nb2/3)O3 solid solution exhibited orthorhombic crystal structures for all compositions. As the x value increased from 0.2 to 0.8, the dielectric constant ɛr increased from 38.24 to 96 and the unloaded quality value Q × f decreased from 42,500 to 12,800 GHz. The temperature coefficient of the resonant frequency (τf) varied from −20 to 138 ppm/°C as the x value increased from 0.2 to 0.8. A new microwave dielectric material, 0.4(La1/2Na1/2)TiO3-0.6Ca(Mg1/3Nb2/3)O3, is suggested for microwave devices, having a dielectric constant ɛr of ∼52.33, a Q × f value of ∼29,700 (at 6.0 GHz), and a τf value of ∼2 ppm/°C. It is proposed as a suitable candidate material for small-sized GPS patch antennas.