The low-temperature sintering and microwave dielectric properties of (Zn_0.7Mg_0.3)TiO₃ ceramics with H₃BO₃

The effects of the addition of H₃BO₃ on the microstructure, phase formation, and microwave dielectric properties of (Zn_0.7Mg_0.3)TiO₃ ceramics sintered at temperatures ranging from 890 °C to 950 °C are investigated. H₃BO₃ as a sintering agent can effectively lower the sintering temperature of ZMT ceramics below 950 °C due to the liquid-phase effect. The microwave dielectric properties are found to strongly correlate with the amount of H₃BO₃. With the increase in H₃BO₃ content, the dielectric constant (ε_r) monotonically increases, but the quality factor (Q × f) reaches a maximum at 1 wt% H₃BO₃, and the apparent density of ZMT ceramics with H₃BO₃ ≥ 1 wt% gradually decreases. At 950 °C, the ZMT ceramics with 1% H₃BO₃ exhibit excellent microwave dielectric properties: ε_r = 19.8, and Q × f = 43800 GHz (8.94 GHz).