Crystal structure and microwave dielectric properties of Li2(Mg1–xCux)2Mo3O12 ceramics sintered at ultra-low temperature

Li 2 (Mg 1– x Cu x ) 2 Mo 3 O 12 (0 ≤ x ≤0.1) ceramics were prepared using the conventional solid-phase method to study the effect of the Cu 2+ substitution for Mg 2+ on the sintering behavior, crystal structure, and microwave dielectric properties of ceramics. The experimental results show that the substitution of Cu 2+ for Mg 2+ reduces the sintering temperature of the ceramics to 550°C. X-ray diffraction patterns show that the introduction of Cu 2+ does not produce a new phase, but rather promotes the formation of Li 2 (Mg 1– x Cu x ) 2 Mo 3 O 12 solid solution. The microwave dielectric properties of the ceramics are influenced by the cell parameters, bond lengths, and structural stability. However, Cu 2+ creates oxygen vacancies during sintering, thereby deteriorating the dielectric properties ( Q × f decreases). The microwave dielectric properties of Li 2 (Mg 1– x Cu x ) 2 Mo 3 O 12 ceramics are optimal at a sintering temperature of 550°C and x = 0.02, with ε r = 9.17, Q × f = 7960 GHz, and τ f = –58.77 ppm/°C. Additionally, these ceramics are compatible with Al electrodes.