Enhancing microwave dielectric properties of Li4NbO4F for LTCC applications through tantalum ion doping

The atomic scale variation of tantalum ion doped Li 4 NbO 4 F ceramics is initially predicted through first principle calculations. Subsequently, Li 4 Nb (1- x ) Ta x O 4 F (0.00 ≤ x ≤ 0.10) ceramics are prepared using the solid phase reaction method. After sintering at 875 °C for 4 h, the Li 4 Nb 0.96 Ta 0.04 O 4 F ceramics exhibit optimum dielectric properties : ε r = 14.73 ± 0.19, Q × f = 83,439 ± 2810 GHz (@9.31 GHz, improved by 41 %), τ f = - 28.33 ± 1.36 ppm/°C. Both the increase in relative density from 95.9 ± 0.32 % to 96.2 ± 0.34 % and the increase in grain size from 14.9 μm to 15.6 μm are non-intrinsic factors that contribute to the optimization of the dielectric properties. Instead, the internal factors suggest that the primary cause of the gradual decrease in ε r is the redshift of the Raman wave number. The reduction in dielectric loss is attributable to the weakening of damping behavior, as well as the increase in lattice energy and electron cloud density. Finally, promising potential of Li 4 Nb 0.96 Ta 0.04 O 4 F ceramics for low-temperature co-fired ceramic (LTCC) applications is indicated by their favourable chemical compatibility with Ag electrodes.