Temperature stable Li2Ti0.75(Mg1/3Nb2/3)0.25O3-based microwave dielectric ceramics with low sintering temperature and ultra-low dielectric loss for dielectric resonator antenna applications

Microwave dielectric ceramics are considered to be one of the key materials of dielectric resonators/filters and have wide application prospects in fifth generation (5G) mobile communication systems. Here we prepared two kinds of low-sintering temperature and high-performance microwave dielectric ceramics with monoclinic rock salt structure by adding a small amount of V2O5 and 0.6CuO–0.4B2O3 sintering aids to Li2Ti0.75(Mg1/3Nb2/3)0.25O3 (LTMN0.25). The sintering temperature of LTMN0.25 ceramics with 2 wt% V2O5 and 1 wt% 0.6CuO–0.4B2O3 additions could be effectively reduced from 1170 °C to below 910 °C due to the liquid phase effects resulting from the additives. Typically, high performance microwave dielectric properties can be obtained in the LTMN0.25 + 2 wt% V2O5 ceramic sintered at 910 °C for 2 h, with a ϵr ∼ 20.7, a Q × f ∼ 60 460 GHz and a TCF ∼ +4.3 ppm °C−1. The best dielectric properties of ϵr ∼ 19.9, a Q × f ∼ 60 950 GHz and a TCF ∼ −6.1 ppm °C−1 were obtained for the samples with 1 wt% 0.6CuO–0.4B2O3 sintered at 870 °C for 2 h. A prototype dielectric resonator antenna (DRA) was fabricated by LTMN0.25 + 1 wt% 0.6CuO–0.4B2O3 ceramic. The antenna resonated at 10.02 GHz with a bandwidth ∼175 MHz at −10 dB transmission loss (S11). Moreover, the chemical compatibility with Ag powder suggests that the LTMN0.25 + 2 wt% V2O5 and LTMN0.25 + 1 wt% 0.6CuO–0.4B2O3 ceramics may be suitable candidates for low temperature co-fired ceramic technology applications.