Dielectric properties of a new ceramic system (mg_0.95zn _0:05)₂tio₄-catio₃ at microwave frequencies

The microwave dielectric properties and microstructure of a two-phase (Mg_0.95Zn_0.05)₂TiO₄-CaTiO ₃ 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 (Mg_0.95Zn_0.05)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°C, 0.92(Mg_0.95-Zn_0.05)2TiO₄-0. 08CaTiO₃ ceramic showed a good combination of microwave dielectric properties: a dielectric constant (ε_r) of -18.03, a quality factor (Q × f) value of -153,000GHz (at 10GHz), and a temperature coefficient of resonant frequency (τ_f) of -16.82ppm/°C. The τ_f value is strongly correlated to the composition and can be controlled by the compositional ratio. Atx = 0.1, an ε_r of -19.15, a Q × f value of -94,400GHz (at 10 GHz), and a τ_f of -1.5ppm/°C were obtained for 0.9(Mg_0.95Zn_0.05) ₂TiO₄-0.1CaTiO₃ ceramic sintered at 1270°C for 4h.