Temperature-Stable <i>x</i>(Na<sub>0.5</sub>Bi<sub>0.5</sub>)MoO<sub>4</sub>–(1–<i>x</i>)MoO<sub>3</sub> Composite Ceramics with Ultralow Sintering Temperatures and Low Dielectric Loss for Dielectric Resonator Antenna Applications
Shu‐Zhao Hao, Di Zhou, Chao Du, Li‐Xia Pang, Charanjeet Singh, Sergei Trukhanov, А.В. Труханов, A. S. B. Sombra, Jobin Varghese, Qiang Li, Xiuqun Zhang
Abstract
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.