Characterization and dielectric behavior of B 2O 3-doped 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 ceramic system at microwave frequency

Abstract

The microwave dielectric properties and the microstructures of (1 − x)Mg 0.95Co 0.05TiO 3– xCa 0.6La 0.8/3TiO 3 ceramic system, prepared by a mixed oxide route, have been investigated. The sintered 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 ceramics with B 2O 3 addition were characterized using X-ray diffraction spectra and scanning electron microscopy (SEM). The microwave dielectric properties are found to strongly correlate with the sintering temperature as well as the amount of B 2O 3 addition. The Q × f value of 0.9Mg 0.95Co 0.05TiO 3–0.1Ca 0.6La 0.8/3TiO 3 ceramic increased with increasing temperature to 1225 °C/4 h and decreased thereafter. The decrease in Q × f value was coincident with the abnormal grain growth. A maximum Q × f value of 76,000 GHz associated with an dielectric constant ( ɛ r ) of 22.67 and a temperature coefficient ( τ f ) of −12 ppm/°C, was achieved for samples with 0.5 wt.% B 2O 3 additions sintering at 1225 °C/4 h. By appropriately adjusting the x value in the (1 − x)Mg 0.95Co 0.05TiO 3– xCa 0.6La 0.8/3TiO 3 ceramic system, zero τ f value can be obtained. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance.