Crystalline structure, chemical bond characteristics, and microwave dielectric properties of temperature-stable (1 − x)SrLaAlO 4 − xCaYAlO 4 (0 ≤ x ≤ 1) ceramics

(1 − x)SrLaAlO 4 − xCaYAlO 4 (0 ≤ x ≤ 1) ceramic samples were prepared via a high-temperature solid-state method at 1500 °C. The phase assemblage, relative density, microstructures, chemical bond characteristics, and microwave dielectric properties of the specimens were investigated. All samples were confirmed to be consisted of a Ruddlesden–Popper (R–P) phase with relatively high relative density levels (i.e., ~ 95%). The dielectric constant ( ε r ) was found to be mainly dependent on the relative density. The quality factor ( Q × f ) was dominated by a synergic effect of the total lattice energy and the tolerance factor. Additionally, the temperature coefficient of the resonance frequency ( τ f ) was influenced by the total bond energy ( E total ) and the linear thermal expansion coefficient. The optimal microwave dielectric properties (i.e., ε r = 18.5, Q × f = 49,700 GHz, and τ f = 0.7 ppm/°C) were achieved at x = 0.6.