Relationship between structure and microwave dielectric properties of Li3Mg4Nb1-xTaxO8 ceramics

Herein, the sintering behavior and dielectric properties of Ta 5+ -doped Li 3 Mg 4 NbO 8 ceramics were investigated by solid-phase reactions in combination with first-principles calculations. In particular, Li 3 Mg 4 Nb 0.96 Ta 0.04 O 8 illustrates the best dielectric properties after sintering at 1,175 °C with ε r  = 13.71 ± 0.20, Q × f  = (132,112 ± 2,391) GHz (increased by 25%) and τ f  = (25.07 ± 1.36) × 10 −6  °C −1 . The non-intrinsic factors reflect that a small amount of Ta 5+ doping produces a secondary phase, increased densification, and grain size, all of which optimize the dielectric properties. The dominant intrinsic factors indicate that the increase in bond ionicity, the greater polarization of Ta 5+ , and the blueshift of the Raman characteristic peak all lead to an increase in ε r . The increase in lattice energy and the decrease in the damping behavior of the Nb/Ta-O bond vibrations lead to an increase in Q × f . The weakening of the Nb/TaO 6 octahedral distortion leads to an optimization of τ f . The modified Li 3 Mg 4 Nb 0.96 Ta 0.04 O 8 ceramics have promising applications in microwave communications.