Microwave dielectric properties of Ca[(Li_1/3Nb_2/3)_1−xM_x]O_3−δ (M = Sn, Ti) ceramics

The microwave dielectric properties of Ca[(Li_1/3Nb_2/3)_1−xM_x]O_3−δ (M = Sn, Ti, 0 ≤ x ≤ 0.5) ceramics were investigated. In general, the ceramics prepared were multiphase materials. However, single-phase specimens having orthorhombic perovskite structure similar to CaTiO₃ could be obtained in the vicinity of Sn = 0.2 to 0.3, and Ti = 0.2. As Sn concentration increased, the dielectric constant (ε_r) decreased and the quality factor (Q) significantly increased within the limited Sn concentration. As Ti concentration increased, the dielectric constant (ε_r) increased, the quality factor (Q) decreased, and the temperature coefficient of resonant frequency (τ_f) changed from a negative to positive value. The temperature coefficient of resonant frequency of 0 ppm/°C was realized at Ti = 0.2. The Q · f_o value and εr for this composition were found to be 26100 GHz and 38.6, respectively.