La2(WO4)3 ceramics' structure, bond properties, and microwave dielectric performance for LTCC applications

La 2 (WO 4 ) 3 microwave dielectric ceramics were prepared using a conventional solid-state reaction method. The effects of sintering temperature (875–950 °C) on densification, phase evolution, microstructure, and microwave dielectric characteristics were thoroughly examined. Phase-pure monoclinic La 2 (WO 4 ) 3 ceramics with space group C2/c were obtained. Optimum sintering at 925 °C yielded the highest relative density (96.5%) and uniform microstructure, resulting in excellent properties: relative permittivity ( ε r ) of 10.8, quality factor ( Q × f ) of 21,780 GHz, and temperature coefficient of resonant frequency ( τ f ) of −51.1 ppm/°C. Structure-property correlations were clarified by applying the Phillips–Van Vechten–Levine chemical bond theory. Quantitative analysis revealed that the high Q × f is primarily governed by the exceptionally high lattice energy of W–O bonds (average ∼12,307 kJ/mol), which suppresses anharmonic lattice vibrations. The negative τ f correlates with the lower bond energy of La–O bonds (∼420 kJ/mol) compared to W–O bonds (∼578 kJ/mol). A modified atomic packing fraction model demonstrated strong positive correlation with Q × f values, indicating that intrinsic packing efficiency dominates dielectric loss in near-fully dense ceramics. This work establishes quantitative links between microscopic bond characteristics and macroscopic dielectric performance, providing a theoretical foundation for designing temperature-stable tungstate-based materials for co-fired low-temperature ceramic applications.