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

Abstract

The atomic scale variation of tantalum ion doped Li4NbO4F ceramics is initially predicted through first principle calculations. Subsequently, Li4Nb(1-x)TaxO4F (0.00 ≤ x ≤ 0.10) ceramics are prepared using the solid phase reaction method. After sintering at 875 °C for 4hours, the Li4Nb0.96Ta0.04O4F ceramics exhibit optimum dielectric properties: εr = 14.73 ± 0.19, Q × f = 83,439 ± 2810GHz (@9.31GHz, improved by 41%), τf = - 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 εr 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 Li4Nb0.96Ta0.04O4F ceramics for low-temperature co-fired ceramic (LTCC) applications is indicated by their favourable chemical compatibility with Ag electrodes.