Improvement of microwave dielectric properties of Ba 2 Ti 9 O 20 ceramics using [Zn 1/3 Nb 2/3 ] 4+ substitution for Ti 4+

Ba 2 [Zn 1/3 Nb 2/3 ] x Ti 9− x O 20 ( x = 0–0.5) ceramics with high-quality factors were successfully prepared via traditional solid-state method. In this work, the microstructure and microwave dielectric properties of the samples were studied. The X-ray diffraction patterns indicated that two different phases BaTi 4 O 9 and Ba 2 Ti 9 O 20 existed at x = 0, while the phase of Ba 2 Ti 9 O 20 was found gradually dominating in specimens with the doping of [Zn 1/3 Nb 2/3 ] 4+ . At the level of x = 0.5, a fraction of the monoclinic phases of Ba 2 Ti 9 O 20 were transformed into the triclinic phase. Furthermore, the SEM and relative density were used to confirm the homogeneous microstructure of the Ba 2 [Zn 1/3 Nb 2/3 ] x Ti 9− x O 20 ceramics. The doping of [Zn 1/3 Nb 2/3 ] 4+ can effectively improve the microwave properties of Ba 2 Ti 9 O 20 ceramics, which are shown as the increase of dielectric constant, quality factor, and the stability of temperature coefficient. Particularly, the excellent microwave dielectric properties were achieved for the Ba 2 [Zn 1/3 Nb 2/3 ] 0.3 Ti 8.7 O 20 ceramics sintered at 1300 °C, with ε r ~ 39.3, a high Q × f ~ 43,879 at 6 GHz, and a τ f ~ + 7 ppm/°C.