Microwave Dielectric Properties of (Mg1-xNix)2TiO4 (x=0.02-0.1) Ceramics

Low-loss ceramics in the system (Mg1-xNix)(2)TiO4 (x = 0.02-0.1) have been prepared using the conventional solid-state ceramic route. The formation of (Mg1-xNix)(2)TiO4 (x = 0.02-0.1) solid solutions was confirmed by the EDX analysis and the lattice parameters measured, which linearly varied from Mg2TiO4 (a = b = c = 8.4410 angstrom) to (Mg0.9Ni0.1)(2)TiO4 (a = b = c = 8.4335 angstrom). The X-ray diffraction analysis also confirmed the coexistence of a cubic-structured (Mg1-xNix)(2)TiO4 and an ilmenite-structured second phase (Mg1-xNix)TiO3. By increasing x, not only could the Q x f of the (Mg1-xNix)(2)TiO4 solid solution be considerably increased from 150,000 GHz at x = 0 to a maximum 238,000 GHz at x = 0.05, the highest epsilon(r) similar to 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 (epsilon(r) similar to 16.43, Q x f similar to 238,000GHz at 9.8 GHz, and tau(f) similar to -55 ppm/degrees C) can be achieved for a specimen using (Mg0.95Ni0.05)(2)TiO4 sintered at 1400 degrees C for 4h.