Structural evolution, sintering behavior and microwave dielectric properties of (1 − x)Li3NbO4-xLiF (0 ≤ x ≤ 0.9)

Sintering behavior, microstructure and microwave dielectric properties of (1 − x)Li₃NbO₄-xLiF (0 ≤ x ≤ 0.9) ceramics have been studied in this paper. Continuous solid solution with rock salt structure formed across the entire compositional range. Phase transformed from ordered body-centered cubic phase to short range ordered face-centered cubic phase with the addition of LiF. The x > 0.4 compositions could be densified at 850 °C/2 h. The optimized Q × f value for each composition increased with the increase of LiF content and saturated at about 75,000 GHz when x ≥ 0.15, whereas the optimized dielectric permittivity decreased with the increase of LiF content. All specimens exhibited negative τ_f value. The chemical compatibilities with copper (Cu) in the case of x = 0.4 composition and silver (Ag) in the case of x = 0.5 composition were also investigated, respectively. No chemical reaction has taken place between the matrix phase and Ag or Cu after sintering at 850 °C/2 h or 950 °C/2 h, respectively.