Influences of Co~(2+) doping on Ba_3(VO_4)_2 ceramic with low dielectric constant, low sintering temperature,high Q*f and positive τ_f

摘要

The dielectric properties and sintering behavior of cobalt-doped Ba_3(VO_4)_2 microwave dielectric ceramic prepared by the traditional solid-state reaction method were systematic researched. The phase structure and grain morphology of the ceramics were studied by XRD and SEM analysis. Densification temperature of cobalt-doped Ba_3(VO_4)_2 was successfully decreased from 1100 to 925 °C. The second-phase Ba_2V_2O_7 was formed as x = 0.05, and the second phase gradually increased as x increased. Electro-magnetic testing results show that the dielectric constant and bulk density were gradually falling with x increased, the Q*f value of ceramic has been improved, and the peak of Q*f obtained is x = 0.3 sintered at 925 °C. The optimal dielectric properties are ε_r = 13.2, Q*f = 54,063 GHz at 10.6 GHz and τ_f = + 18.7 ppm/°C, sintered at 925 °C, which may be widely used in adjustment of τ_f for LTCC ceramics with negative τ_f while maintaining excellent performances.