Phase-assisted densification and enhanced microwave dielectric properties in Li3Mg4NbO8 ceramics via V5+ substitution

A phase-assisted densification mechanism induced by V 5+ substitution is identified. • Secondary phase formation significantly reduces the sintering temperature by 100 °C. • Dielectric loss is dominated by phonon damping rather than lattice energy • Optimal Q×f is achieved through minimized Raman FWHM and reduced phonon scattering. • Improved τ f originates from reduced Nb/VO 6 octahedral distortion. Microwave dielectric ceramics with low ε r , high Q×f, and near-zero τ f are essential for advanced wireless communication systems. In this work, Li 3 Mg 4 Nb 1- x V x O 8 (0.00 ≤  x  ≤ 0.10) ceramics were synthesized, and the effects of V 5+ substitution on phase evolution, sintering behavior, and dielectric properties were systematically investigated. V 5+ doping induces the formation of a Mg 4 (Nb/V) 2 O 9 secondary phase, enabling a phase-assisted densification mechanism that reduces the optimal sintering temperature from 1175 °C to 1075 °C. The optimal composition ( x  = 0.02) exhibits ε r = 13.65 and Q×f = 121,296 GHz. Raman and chemical bond analyses reveal that dielectric loss is primarily governed by phonon damping behavior, with the minimum Raman peak width corresponding to the highest Q×f . In contrast, lattice energy shows no direct correlation with dielectric loss. The improved τ f is attributed to reduced Nb/VO 6 octahedral distortion. These results demonstrate that synergistic regulation of phase evolution and lattice vibration provides an effective strategy for optimizing microwave dielectric performance. Download: Download high-res image (187KB) Download: Download full-size image