Dielectric properties of low loss (1-x)(Mg0.95Zn0.05)TiO3-xSrTiO3 ceramic system at microwave frequency

The microstructures and the microwave dielectric properties of the (1-x)(Mg0.95Zn0.05)TiO3-xSrTiO(3) ceramic system were investigated. (Mg0.95Zn0.05)TiO3 possesses high dielectric constant (epsilon(r)similar to 17.05), high quality factor (Q x f value similar to 264 000 at 9 GHz), and negative tau(f) value (-40.31 ppm/degrees C). In order to achieve a temperature-stable material, SrTiO3, having a large positive tau(f) value of 1700 ppm/degrees C, was added to (Mg0.95Zn0.05)TiO3. 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 degrees C and caused an increase in the dielectric loss of the system. As the x value varies from 0 to 0.1, (1-x)(Mg0.95Zn0.05)TiO3-xSrTiO(3) ceramic system has the dielectric properties as follows: 17.05 <epsilon(r)< 26.35, 20 000 < Q x f < 264 000, and -41 <tau(f)< 140. By appropriately adjusting the x value in the (1-x)(Mg0.95Zn0.05)TiO3-xSrTiO(3) ceramic system, zero tau(f) value can be achieved. A new microwave dielectric material, 0.96(Mg0.95Zn0.05)TiO3-0.04SrTiO(3) applicable in microwave devices is suggested and possesses the dielectric properties of a dielectric constant epsilon(r)similar to 20.96, a Q x f value similar to 135 000 GHz (at 9 GHz), and a tau(f) value similar to 0 ppm/degrees 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.