Correlation between Sn substitution for Ti and Microwave Dielectric Properties of Magnesium Titanate Ceramics

The relationship between Sn substitution for Ti and microwave dielectric properties of Mg(Ti 1‐ x Sn x )O 3 ceramics was investigated. Sn 4+ could substitute for Ti 4+ in MgTiO 3 and increase the crystal volume. All samples exhibited the MgTiO 3 ‐type phase with ilmenite structure as main phase. At the x range from 0 to 0.05, the secondary phase of Mg 2 TiO 5 was observed. Upon further increasing Sn content up to 0.15, the SnO 2 phase appeared. When the x value increased from 0 to 0.05, the dielectric constant decreased slightly and the quality factor increased sharply, whereas the dielectric constant increased and the quality factor decreased as the x value varied from 0.05 to 0.15. The temperature coefficient of resonant frequency moved toward positive value with Sn substitution. In particular, at the x range from 0.05 to 0.07, the ceramic sintered at 1360°C for 4 h exhibited excellent microwave dielectric properties of ε r  = 16.8–17.1, Q f  = 298,000–312,000 and τ f  = −53~−50 ppm/°C.