Mg/Ti co‐substituted CaSmAlO4‐based microwave dielectric ceramics with temperature stability in a wide temperature range

To obtain microwave dielectric ceramics with excellent dielectric properties and temperature stability over a wide temperature range, we co‐substituted CaSmAlO4 ceramics with Mg/Ti and prepared CaSmAl1−x(Mg0.5Ti0.5)xO4 (0.1 ≤ x ≤ 0.4) ceramics using traditional solid‐state methods. It was found that some Al3+ was replaced by composite ions (Mg0.5Ti0.5)3+, which optimized the dielectric properties of the ceramics. As the substitution amount increases, the dielectric constant of the sample increases synchronously, whereas the quality factor gradually decreases. The temperature coefficient of the resonant frequency first increases and then falls. Finally, the CaSmAl1−x(Mg0.5Ti0.5)xO4 (0.1 ≤ x ≤ 0.4) ceramics obtained excellent dielectric properties after sintering at 1450°C for 4 h at a substitution x of 0.2: εr = 19.9, Q × f = 64 920 GHz, τf = 3.17 ppm/°C (−40 to 25°C), and 0.17 ppm/°C (25–125°C).