Microwave dielectric properties of sol-gel derived BaTi₄O₉and Ba₂Ti₉O₂₀:B₂O₃ceramics

BaTi4O9and B2O3-doped Ba2Ti9O20ceramics powders have been prepared by a sol-gel route. The phase evolution, grain size and dielectric properties of the BaTi4O9and Ba2Ti9O20-based ceramics powders have been investigated. These results show that the BaTi4O9and 5 wt% B2O3-doped Ba2Ti9O20ceramics powders calcined at 800°C for 2 h with the grain sizes of 30-80 and 50-200 nm, respectively. Monophase sample of BaTi4O9with orthorhombic symmetry could be obtained after the BaTi4O9precursor was calcined at 1200°C for 2 h, whereas, monophase sample of 5 wt% B2O3-doped Ba2Ti9O20was obtained at 800°C for 2 h. The BaTi4O9and Ba2Ti9O20: 5 wt% B2O3ceramics fabricated using the sol-gel powders were found to have microwave dielectric properties with εr= 36.1, Q = 3220 at 5.31 GHz, and εr= 34.5, Q = 2425 at 5.53 GHz, respectively. The effect of sintering temperatures on the microwave dielectric properties of the Ba2Ti9O20: 5 wt% B2O3ceramics was studied.