Microwave Dielectric Properties of (Mg 1− x Ni x ) 2 TiO 4 ( x =0.02–0.1) Ceramics

Low‐loss ceramics in the system (Mg 1− x Ni x ) 2 TiO 4 ( x =0.02–0.1) have been prepared using the conventional solid‐state ceramic route. The formation of (Mg 1− x Ni x ) 2 TiO 4 ( x =0.02–0.1) solid solutions was confirmed by the EDX analysis and the lattice parameters measured, which linearly varied from Mg 2 TiO 4 ( a = b = c =8.4410 Å) to (Mg 0.9 Ni 0.1 ) 2 TiO 4 ( a = b = c =8.4335 Å). The X‐ray diffraction analysis also confirmed the coexistence of a cubic‐structured (Mg 1− x Ni x ) 2 TiO 4 and an ilmenite‐structured second phase (Mg 1− x Ni x )TiO 3 . By increasing x , not only could the Q × f of the (Mg 1− x Ni x ) 2 TiO 4 solid solution be considerably increased from 150,000 GHz at x =0 to a maximum 238,000 GHz at x =0.05, the highest ɛ r ∼16.43 could also be obtained simultaneously. This was mainly due to the uniform grain morphology and the highest density of the specimen. A good combination of microwave dielectric properties (ɛ r ∼16.43, Q × f ∼238,000 GHz at 9.8 GHz, and τ f ∼−55 ppm/°C) can be achieved for a specimen using (Mg 0.95 Ni 0.05 ) 2 TiO 4 sintered at 1400°C for 4 h.