Enhancement of temperature stability for magnesium niobite system by direct doping with titanium dioxide

Heterovalent ion doping has been playing a remarkably significant role in the microwave dielectric performances of columbite A2+Nb2O6 (A2+ = Zn, Ca, or transition metal). Here, the Q × f value of MgNb2O6 ceramics can be effectively enhanced from 32,893 GHz to 117,659 GHz by doping with 1 mol% (TiW)5+. Based on the high Q value of Mg(Nb0.98Ti0.01W0.01)2O6, TiO2 was selected to further adjust the τf value of the matrix material prepared by the conventional solid-state reaction method. The results show that the Mg(Nb0.98Ti0.01W0.01)2O6 ceramics undergo three phase zones with increasing TiO2 content: columbite (MgNb2O6) solid solution, a mixture of columbite and rutile (Ti0.5Mg0.167Nb0.333O2), and Ti0.5Mg0.167Nb0.333O2 solid solution. This variation in phase formation has an essential effect on the microwave dielectric behavior of Mg(Nb0.98Ti0.01W0.01)2O6@xTiO2 (0.03 ≤ x ≤ 0.25) ceramics. It is important to note that at x = 0.17, the specimen has excellent microwave dielectric performances, with εr = 34.79, Q × f = 24,103 GHz, and the τf of the specimen may be adjust to zero. It is anticipated that these materials will be utilised in contemporary microwave and telecommunication equipment.