Low-temperature sintered Ba₁₆ZrNb₁₂O₄₈-BaWO₄ composite ceramics with near-zero τ_f and enhanced Q×f for LTCC applications

Perovskite-structured ceramics are promising for their tunable properties, while LTCC technology requires low sintering temperatures and near-zero τ _f . BaCu(B₄O₈) as a sintering aid reduced Ba₁₆ZrNb₁₂O₄₈’s sintering temperature from 1450 ℃ to 1000 ℃. A two-phase strategy designed (1 − x )Ba₁₆ZrNb₁₂O₄₈- x BaWO₄ + 5 wt% BaCu(B₄O₈) ( x = 0.88–0.93) ceramics for τ _f modulation. Ba₁₆ZrNb₁₂O₄₈ with 5 wt% BaCu(B₄O₈) densified at 1000 ℃, yielding ε _r = 32.6, Q×f = 22,400 GHz, τ _f = +44.2 ppm/℃, and ρ _bulk = 5.83 g/cm³. Notably, x = 0.92 with 5 wt% BaCu(B₄O₈), co-fired at 950 ℃ and annealed, achieved τ _f = +7.4 ppm/℃ (near-zero), Q×f = 29,100 GHz, and ε _r = 20.0. XRD/SEM-EDS confirmed chemical inertness and no Cu diffusion at the ceramic/electrode interface. These features make it a promising LTCC candidate.