Dielectric Properties of Low Loss (1– <i>x</i> )(Mg _0.95 Zn _0.05 )TiO ₃ – <i>x</i> SrTiO ₃ Ceramic System at Microwave Frequency

Abstract

The microstructures and the microwave dielectric properties of the (1– x )(Mg 0.95 Zn 0.05 )TiO 3 – x SrTiO 3 ceramic system were investigated. (Mg 0.95 Zn 0.05 )TiO 3 possesses high dielectric constant (ɛ r ∼17.05), high quality factor ( Q × f value∼264 000 at 9 GHz), and negative τ f value (−40.31 ppm/°C). In order to achieve a temperature‐stable material, SrTiO 3 , having a large positive τ f value of 1700 ppm/°C, was added to (Mg 0.95 Zn 0.05 )TiO 3 . Two‐phase system was confirmed by the X‐ray diffraction patterns and the measured lattice parameters. Evaporation of Zn occurred at temperatures higher than 1300°C and caused an increase in the dielectric loss of the system. As the x value varies from 0 to 0.1, (1– x )(Mg 0.95 Zn 0.05 )TiO 3 – x SrTiO 3 ceramic system has the dielectric properties as follows: 17.05&lt;ɛ r &lt;26.35, 20 000&lt; Q × f &lt;264 000, and −41&lt;τ f &lt;140. By appropriately adjusting the x value in the (1– x )(Mg 0.95 Zn 0.05 )TiO 3 – x SrTiO 3 ceramic system, zero τ f value can be achieved. A new microwave dielectric material, 0.96(Mg 0.95 Zn 0.05 )TiO 3 –0.04SrTiO 3 applicable in microwave devices is suggested and possesses the dielectric properties of a dielectric constant ɛ r ∼20.96, a Q × f value∼135 000 GHz (at 9 GHz), and a τ f value ∼0 ppm/°C. A compact band‐pass filter using two open‐loop ring resonators with asymmetric tapping feed lines is designed and fabricated using the proposed dielectric to study its performance.