LAUSR

Abstract The Ba2-xCaxMgTi5O13 (0 ≤ x ≤ 0.3) microwave dielectric ceramics were for the first time prepared via a conventional solid-state reaction method. A small amount of Ca2+ can dissolve into the lattice by forming solid solutions with a monoclinic structure (C2/m) and further influence the sintering behavior, grain growth and microwave dielectric properties of Ba2-xCaxMgTi5O13 ceramics. Both increase of er and decrease of Qxf with x should be associated with increased lattice distortion and uneven grain growth although the sample density and the ratio of the ionic polarizability to the molar volume show little variation. Moreover, the A-site bond valence and τf indicate a close relation in current study, such that the Ca2+substitution can induce an increase of τf values. The optimum microwave dielectric properties of er ∼ 29.3, Qxf ∼ 30,870 GHz (6.5 GHz), and a near-zero τf ∼ +2.1 ppm/°C can be contained in the x = 0.15 ceramic sintered at 1160 °C.