Dielectric Properties of a New Ceramic System (Mg0.95Zn0.05)2TiO4-CaTiO3 at Microwave Frequencies

The microwave dielectric properties and microstructure of a two-phase (Mg0.95Zn0.05)(2)TiO4-CaTiO3 ceramic system prepared using the conventional solid-state route were investigated. The structure and microstructure were analyzed by X-ray diffraction and scanning electron microscopy, respectively. Ilmenite-structured (Mg0.95Zn0.05)TiO3 was detected as a second phase. The coexistence of the second phase, however, did not degrade the dielectric properties of the specimen because the phases were compatible. At 1270 degrees C, 0.92(Mg0.95Zn0.05)(2)TiO4-0.08CaTiO(3) ceramic showed a good combination of microwave dielectric properties: a dielectric constant (epsilon(r)) of similar to 18.03, a quality factor (Q x f) value of similar to 153,000 GHz (at 10 GHz), and a temperature coefficient of resonant frequency (tau(f)) of similar to-16.82 ppm/degrees C. The tau(f) value is strongly correlated to the composition and can be controlled by the compositional ratio. At x = 0.1, an epsilon(r) of similar to 19.15, a Q x f value of similar to 94,400 GHz (at 10 GHz), and a tau(f) of similar to 1.5 ppm/degrees C were obtained for 0.9(Mg0.95Zn0.05)(2)TiO4-0.1CaTiO(3) ceramic sintered at 1270 degrees C for 4 h. (C) 2009 The Japan Society of Applied Physics DOI: 10.1143/JJAP.48.071402