Crystal structure and phase formation of MgO–MoO3‐based ceramics with ultralow dielectric loss: A comprehensive study

Abstract The MgO‐MoO 3 system shows significant potential for applications in microwave dielectric ceramics. However, the formation mechanism, crystal structures, and microwave dielectric properties of this system have not been systematically investigated. This work aims to comprehensively study the crystal structures, phase transitions, and microwave dielectric properties of compounds in the MgO‐MoO 3 system. In particular, the research delves into the unexplored transformation mechanism from β‐MgMo 2 O 7 to α‐MgMo 2 O 7 and MgMoO 4 . As a result, the three compounds exhibiting favorable microwave dielectric properties have been successfully fabricated. These compounds can be effectively sintered at temperatures ranging from 685 to 900°C and exhibited dielectric constants (ε r ) ranging from 5.41 to 6.89, as well as Qf values ranging from 100 000 to 130 000 GHz. Additionally, prototype microstrip antennas are designed and fabricated using β‐MgMo 2 O 7 and MgMoO 4 ceramics as substrates. The obtained antenna's performance is excellent, with S 11 values below −30 dB and a gain exceeding 6 dB at 5.8 GHz, highlighting the potential of the developed ceramics for practical applications in microwave devices.