Structure, chemical bonding characteristics and microwave dielectric properties of Li5Mg3Ti2O9F ceramic with low sintering temperature

Li 5 Mg 3 Ti 2 O 9 F (LMTOF) ceramic was successfully synthesized using the solid-state reaction method at a temperature of 925 °C. XRD analysis revealed the presence of a unique cubic structure, resulting in the formation of a solid solution of Li 5 Mg 3 Ti 2 O 9 F. Notably, a significant correlation was observed between the ions polarization and the ε r of the LMTOF ceramic. Furthermore, the impact of sintering temperature on the ε r and Q  ×  f value of the ceramic was primarily evidenced by changes in the sintered density. Applying the P–V-L theory, computational results highlighted the crucial role played by the ionicity of Mg–O/F and Ti–O/F in determining the behavior of the LMTOF ceramic. Particularly, the lattice energy associated with the Ti–O/F bond exerted a predominant influence on the Q  ×  f value, while the bond energy of Li–O/F exhibited a greater impact on the τ f . Additionally, insightful details regarding the lattice vibrations of the ceramic were obtained through Raman spectroscopy. Impressively, the ceramic sintered at 925 °C exhibited exceptional microwave dielectric performance, demonstrating an ε r of 14.8, a Q  ×  f value of 98,500 GHz, and a τ f of −15.6 ppm/°C. These outcomes underscore the significant potential of LMTOF ceramic for advancements in the LTCC field.