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) 0.5 MoO 4 –(1– x )MoO 3 (0.2 ≤ x ≤ 0.9, abbreviated as x NBM–(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 Q f value (12,080 to 8600 GHz), and increasing τ f 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 ε r ∼ 24.4, Q f ∼ 9030 GHz (7.7 GHz), and a near-zero τ f ∼ 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 ( S 11 ). Furthermore, the chemical compatibility with Al powder indicates that the x NBM–(1– x )MO composite ceramics may be promising microwave materials for applications in ultralow-temperature co-fired ceramic technology.