Improvement of microwave dielectric properties of Ba2Ti9O20 ceramics using [Zn1/3Nb2/3]4+ substitution for Ti4+

Abstract

Ba2[Zn1/3Nb2/3]xTi9−xO20 (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 BaTi4O9 and Ba2Ti9O20 existed at x = 0, while the phase of Ba2Ti9O20 was found gradually dominating in specimens with the doping of [Zn1/3Nb2/3]4+. At the level of x = 0.5, a fraction of the monoclinic phases of Ba2Ti9O20 were transformed into the triclinic phase. Furthermore, the SEM and relative density were used to confirm the homogeneous microstructure of the Ba2[Zn1/3Nb2/3]xTi9−xO20 ceramics. The doping of [Zn1/3Nb2/3]4+ can effectively improve the microwave properties of Ba2Ti9O20 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 Ba2[Zn1/3Nb2/3]0.3Ti8.7O20 ceramics sintered at 1300 °C, with er ~ 39.3, a high Q × f ~ 43,879 at 6 GHz, and a τf ~ + 7 ppm/°C.