Ca_4−xLa_2+xTi_5−xB_xO₁₇ (B = Al, Ga) dielectric ceramics for microwave applications

In this study, Ca_4−xLa_2+xTi_5−xB_xO₁₇ (B = Al, Ga; x = 0, 1) ceramics were processed via a mixed oxide solid state sintering route and characterized using XRD, SEM, EDS and Vector Network Analyzer. Phase analysis of the samples showed single phase formation for the sample x = 0 while secondary phases formed for Ca_4−xLa_2+xTi_5−xB_xO₁₇ (B = Al, Ga; x = 1) ceramics. Ca₄La₂Ti₅O₁₇ exhibited ∈_r = 74, Q×f_o = 14,116 GHz and τ_f = 157 ppm/°C. The substitution of Ga or Al for Ti at the B-site of Ca₄La₂Ti₅O₁₇ ceramics significantly improved the microwave dielectric properties i.e. Ca₃La₃Ti₄GaO₁₇ and Ca₃La₃Ti₄AlO₁₇ have ∈_r = 44, Q×f_o = 16,128 GHz and τ_f = 7.3 ppm/°C and ∈_r = 46, Q×f_o = 13,754 GHz and τ_f = −2 ppm/°C, respectively. The microwave dielectric properties of these materials are suitable for high frequency microwave applications.