Crystal structure and microwave dielectric properties of CaTiO3-La [Ga(1-δ)Alδ]O3 ceramics system

The crystal structure and microwave dielectric properties of 0.64CaTiO(3)-0.36La[Ga(1-delta)Al delta]O-3 specimens have been investigated in this work. When delta <= 0.5, the crystal structure of 0.64CaTiO(3)-0.36La[Ga(1-delta)Al delta]O-3 was orthorhombic, while it transformed into the tetragonal structure when delta>0.5. When delta=0.5, specimens exhibited good microwave dielectric properties with epsilon(r)=45.54, Q x f = GHz) and tau(f)=-1.7 ppm/degrees C. The 50 at% substitution of Ga3+ by Al3+. in 0.64CaTiO(3)-0.36LaGaO(3) benefited the Q x f value, the results showed that all samples of xCaTiO(3)-(1-x)La[Ga0.5Al0.5]O-3 (x = 0.62, 0.63, 0.64, 0.65, 0.66) exhibited rho(r) >= 96.8%, Q x f >= 39,000GHz, 44 <= epsilon(r) <= 48 and -8 PPm/degrees C <= tau(f) <= +6 ppm/degrees C. (C) 2014 Elsevier Ltd. All rights reserved.