Microwave Dielectric Properties of Sol-Gel Derived BaTi₄O₉ and Ba₂Ti₉O₂₀:B₂O₃ Ceramics

Abstract

BaTi₄O₉ and B₂O₃-doped Ba₂Ti₉O₂₀ ceramics powders have been prepared by a sol-gel route. The phase evolution, grain size and dielectric properties of the BaTi₄O₉ and Ba₂Ti₉O₂₀-based ceramics powders have been investigated. These results show that the BaTi₄O₉ and 5 wt% B₂O₃-doped Ba₂Ti₉O₂₀ ceramics powders calcined at 800^∘C for 2 h with the grain sizes of 30–80 and 50–200 nm, respectively. Monophase sample of BaTi₄O₉ with orthorhombic symmetry could be obtained after the BaTi₄O₉ precursor was calcined at 1200^∘C for 2 h, whereas, monophase sample of 5 wt% B₂O₃-doped Ba₂Ti₉O₂₀ was obtained at 800^∘C for 2 h. The BaTi₄O₉ and Ba₂Ti₉O₂₀: 5 wt% B₂O₃ ceramics fabricated using the sol-gel powders were found to have microwave dielectric properties with ε _r = 36.1, Q = 3220 at 5.31 GHz, and ε _r = 34.5, Q = 2425 at 5.53 GHz, respectively. The effect of sintering temperatures on the microwave dielectric properties of the Ba₂Ti₉O₂₀: 5 wt% B₂O₃ ceramics was studied.