Effect of V2O5 on microwave dielectric properties of non-stoichiometric MgTiO3 ceramics

• Combined effects of MgO and V2O5 on MTO ceramics were studied for the first time.
• MTO with 0.07 mol excess MgO show a pure phase with excellent dielectric properties.
• V2O5 forms a solid solution with MTO, densified at 1100 °C due to liquid phase effect.
• Microwave dielectric loss is heavily influenced by grain size and secondary phases.
• Obtained MTO properties are suitable for LTCC and low-loss microwave applications.

We report the effect of V2O5 addition on crystal structure, microstructure and microwave dielectric properties of non-stoichiometric MgTiO3 (Mg1+δTiO3+δ, where δ is excess MgO concentration) ceramics. The structural studies reveal that sample with δ = 0.07 exhibits a single phase MgTiO3 and secondary phase of MgTi2O5 (Mg2TiO4) for below (above) the δ = 0.07 composition. The optimum microwave dielectric properties of ɛr ∼ 17.68, Q × f0 ∼ 161 THz at 9.4 GHz are obtained for δ = 0.07, sintered at 1350 °C for 3 h. The improvement in loss is attributed to the improvement in uniform grain growth and suppression of secondary phases. V2O5 addition significantly lowered the sintering temperature of Mg1.07TiO3.07 to 1100 °C, which is due to the formation of liquid phase. The XRD analysis reveals that V2O5 forms a solid solution with MTO. A good combination of ɛr ∼ 15.8 and Q × f0 of 85.6 THz at 9.3 GHz are obtained for 0.5 wt% V2O5 added Mg1.07TiO3.07.