Abstract
The microstructures and microwave dielectric properties of the (1 − x)Sr0.2Na0.4Sm0.4TiO3–xLnAlO3 samples (where Ln stands for Nd, Pr and Sm, x = 0.2–0.3) were studied. The XRD result showed that the (1 − x)Sr0.2Na0.4Sm0.4TiO3–xLnAlO3 (Ln = Nd, Pr and Sm) solid-solutions with single orthorhombic perovskite phase could be formed in the componential range of 0.2 ≤ x ≤ 0.3. With an increasing of Ln3+ content, the dielectric constant (e r ) decreased due to the smaller dielectric polarizability of LnAlO3 than that of Sr0.2Na0.4Sm0.4TiO3. With increasing x from 0.2 to 0.3, the quality factor (Q·f) firstly increased and then decreased for the specimens with PrAlO3, because the Q·f values were strongly depended on grain sizes. Moreover, either increasing the A-site bond valence or decreasing the B-site bond valence led to a decrease in the temperature coefficient of the resonant frequency (τ f). Typical values of e r ~ 52.7, Q·f ~ 9700 GHz (at 4.33 GHz) and τ f ~ 1.5 ppm/°C were obtained for the (1 − x)Sr0.2Na0.4Sm0.4TiO3–xSmAlO3 (x = 0.25) ceramic sintered at 1470 °C for 4 h.
Published Version
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