Low loss Sr1−xCaxLa4Ti5O17 microwave dielectric ceramics

Abstract Microwave dielectric ceramics in the Sr 1− x Ca x La 4 Ti 5 O 17 (0 ≤ x ≤ 1) composition series were prepared through a solid state mixed oxide route. All the compositions formed single phase ceramics within the detection limit of in-house X-ray diffraction when sintered in the temperature range 1450–1580 °C. Theoretical density and molar volume decreased due to the substitution of Ca 2+ for Sr 2+ which was associated with a decrease in the dielectric constant ( ɛ r ) and temperature coefficient of resonant frequency ( τ f ) but an increase in quality factor, Qf o . Optimum properties were achieved for Sr 0.4 Ca 0.6 La 4 Ti 5 O 17 which exhibited, ɛ r ∼ 53.7, Qf o ∼ 11,532 GHz and τ f ∼ −1.4 ppm/°C.