Impacts of Mg-site non-stoichiometry on lattice structure and microwave dielectric properties of BaMg2+xV2O8 ceramics for LTCC application

In this work, a series of BaMg2+xV2O8 (0.04 ≤ x ≤ 0.16) ceramics possessing exceptional Q×f were synthesized within 900–975 °C, all exhibiting a single tetragonal phase attributed to the I41/acd (142) space group. A series of investigations were conducted to analyze the impacts of non-stoichiometric Mg2+ ions on the lattice structure, microscopic morphology, and microwave dielectric properties of BaMg2+xV2O8 (0.04 ≤ x ≤ 0.16) ceramics. It's found that optimal grain growth and enhanced density can be achieved through the introduction of a suitable amount of non-stoichiometric Mg2+ ions, and this consequential effect extends to the εr and Q×f value. Specifically, the εr demonstrated a significant association with the average bond-ionicity while the Q×f value showed to be associated with the lattice energy that reflects the degree of anharmonic vibrations within the lattice. The investigation of Mg-site non-stoichiometry can provide valuable theoretical support for further investigation of substitution within BaMg2V2O8 ceramics. When sintered at 950 °C, the BaMg2.08V2O8 ceramics exhibited the optimum Q×f value of 164, 646 GHz, along with εr of 13.4 and τf of −18.04 ppm/°C, indicating the promising attributes for use in low-temperature co-fired ceramic (LTCC) applications.