Effect of Sb5+ ion substitution for Nb5+ on crystal structure and microwave dielectric properties for Li3Mg2NbO6 ceramics

The Li3Mg2(Nb1-xSbx)O6 (0.02 ≤ x ≤ 0.08) ceramics were prepared by partial substitution of Sb5+ on Nb5+ site for the first time. The effects of Sb5+ ion substitution on the microstructures and microwave dielectric properties were discussed in detail. The relationship between structural characteristics and dielectric properties of Li3Mg2(Nb1-xSbx)O6 ceramics was investigated based on the complex chemical bond theory. Synthesized via the solid-state reaction route, Li3Mg2(Nb1-xSbx)O6 ceramics exhibited excellent dielectric properties. With the increase of Sb5+ substitution amount, εr increased, Q × f values first went up then fell, and τf shifted for the positive direction. The bond ionicity, lattice energy and bond energy of Li3Mg2(Nb1-xSbx)O6 ceramics were employed to study the crystal structure and dielectric properties. Typically, the best dielectric properties with a εr of 15.79, Q × f value of 95,487 GHz and τf of −24.53 ppm/oC were obtained in Li3Mg2(Nb1-xSbx)O6 (x = 0.06) ceramics sintered at 1150 °C for 6 h.