Microwave Dielectric Properties of Ca4La2Ti5−x(Mg1/3Nb2/3)xO17
Using the solid‐state ceramic route, Ca4La2Ti5−x
(0 ≤ x ≤ 4) ceramics were prepared, and the phase purity, microstructure, and microwave dielectric properties were investigated. The XRD results suggest the formation of solid solutions for all studied compositions (0 ≤ x ≤ 4)
and the unit cell volume increases linearly with x. The SEM results also show no evidence of secondary phase and doping (Mg1/3Nb2/3) at Ti
site promotes the grain growth. The εr of sintered ceramics decreases from 71.86 to 35.23, the Q × f value increases from 15 070 to 21 277 GHz and the τ
value varies from 125.2 to −16.7 ppm/°C
with x increasing from 0 to 4. A near‐zero τ
(~1.62 ppm/°C) is achieved at x = 3 with εr ~ 40.45 and Q × f ~ 19 123 GHz.