With the support of density functional theory (DFT) calculation, the amelioration of sintering and dielectric properties of the Mg₃B₂O₆ (MBO) ceramic was realized through the substitution of magnesium with nickel. The TE-mode cylindrical cavity method was used to measure the dielectric properties at different frequencies. The thermo-mechanical analysis and simultaneous thermal analysis were used to characterize the chemical and mechanical properties. The phase composition was determined through the X-ray diffraction (XRD) and Raman spectrum. The microstructure was investigated using the scanning electron microscopy (SEM). Magnesium substitution with nickel (4 mol%) could ionize the B-O bond of BO₃, modify the vibration mode, improve the order degree, densify the microstructure, decrease the intrinsic densification temperature, and ameliorate the dielectric properties of the MBO ceramics. The maximum values were achieved for the ceramics with 4 mol% nickel and sintered at 1175 ℃, that is, 97.2% for relative density, 72,600 GHz (10 GHz), 75,600 GHz (11.4 GHz), and 92,200 GHz (15 GHz) for Q × f, 7.1 (10 GHz), 7.01 (11.4 GHz), and 6.91 (15 GHz) for ε_r, and -56.3 ppm/℃ for τ_f.

The crystal structure, Raman vibration, chemical bond characteristics, and microwave dielectric properties of Zn_1-xCu_xWO₄ (x = 0–0.15) ceramics prepared by a solid-state reaction were investigated by XRD refinement, Raman spectroscopy, P-V-L theory and XPS. According to the P-V-L theory, the properties of the W-O bond are stronger than those of the Zn-O bond, which makes a major contribution to the dielectric properties. The relative permittivity is mainly affected by the average bond ionicity, and the variations in the dielectric loss and τ_f are mainly attributed to the lattice energy and bond energy. XPS shows that the presence of Cu⁺ could produce oxygen vacancy defects, increasing the dielectric loss. Additionally, Raman spectra show that the increasing molecular polarizability causes the Raman shift to move to a low wavenumber, and the changes in Raman intensity and FWHM lead to a decrease in the degree of short-range ordering. Particularly, Zn_0.97Cu_0.03WO₄ ceramics sintered at 925 ℃ showed satisfactory properties (ε_r = 14.20, tanδ = 1.473 × 10⁻⁴ at 9.087 GHz, and τ_f = −40 ppm/℃), which can potentially be applied to LTCC technology and indicate that Cu substitution can not only reduce the sintering temperature, but also optimize the dielectric properties.