The effect of non-stoichiometry on the microstructure and microwave dielectric properties of the Mg1+δTiO3+δ ceramics

The microwave dielectric properties and microstructure of Mg1+δTiO3+δ (−0.05 ≤ δ ≤ 0.05) ceramics prepared via the conventional solid-state route were investigated. A slight deviation from stoichiometry does not practically affect the relative permittivity and temperature coefficient of resonant frequency of the specimen. However, the Q × f value is very sensitive to the composition and it shows a non-linear variation corresponding to a relative amount of Mg. A very high Q × f can be achieved for specimen with single MgTiO3 phase, which can be obtained within the compositional range −0.02 ≤ δ ≤ 0.02. In addition, a low Q × f measured for specimens at δ < −0.02 can be attributed to the presence of second phase MgTi2O5. An extremely high Q × f of ∼357,600 GHz (at 10 GHz) together with an ɛr of ∼18.3 and a τf of ∼−50 ppm/°C can be found for specimen using Mg1.02TiO3.02.

► Effect of non-stoichiometry on microstructure and microwave dielectric properties of Mg1+δTiO3+δ ceramics was reported. ► A very high Q × f could be achieved within a narrow homogeneity region 0 ≤ δ ≤ 0.02. ► An extremely high Q × f of ∼357,600 GHz (at 10 GHz) can be found for specimen using Mg1.02TiO3, which is ∼125% higher than that of MgTiO3.