Temperature-Stable x(Na0.5Bi0.5)MoO4–(1–x)MoO3 Composite Ceramics with Ultralow Sintering Temperatures and Low Dielectric Loss for Dielectric Resonator Antenna Applications

Fifth-generation mobile communication systems provide a huge market for microwave dielectric materials, especially in the manufacture of dielectric resonators, filters, substrates, and antennas. Herein, an excellent performance microwave dielectric ceramic x(NaBi)0.5MoO4–(1–x)MoO3 (0.2 ≤ x ≤ 0.9, abbreviated as xNBM–(1–x)MO sintered below 660 °C with two coexisting phases is prepared via a solid solution reaction. With the increasing x value, the sintering temperature rises from 600 to 640 °C. The dielectric properties have a series of changes with increasing permittivity (10.3–28.1), decreasing Qf value (12,080 to 8600 GHz), and increasing τf value (−27.1 to +21.2 ppm/°C). Typically, at the ultralow temperature of 630 °C, the 0.8NBM–0.2MO ceramic exhibits great microwave performance with εr ∼ 24.4, Qf ∼ 9030 GHz (7.7 GHz), and a near-zero τf ∼ 7.2 ppm/°C. A prototype dielectric resonator antenna is manufactured using a 0.8NBM–0.2MO ceramic. A high-impedance bandwidth ∼360 MHz can be obtained in the antenna at 7.74 GHz with −10 dB transmission loss (S11). Furthermore, the chemical compatibility with Al powder indicates that the xNBM–(1–x)MO composite ceramics may be promising microwave materials for applications in ultralow-temperature co-fired ceramic technology.