The Reaction Sequence and Dielectric Properties of BaAl_2Ti_5O_(14) Ceramics

摘要

To investigate the correct reaction sequence of BaO-Al_2O_3-5TiO_2 system, powders calcined at different temperatures are analyzed by x-ray diffraction. The results show that the source phase BaCO_3 decomposes below 800℃, TiO_2 and Al_2O_3 start to consume at 900 and 1100℃, respectively. BaTi_4O_9 phase appears at 1000℃ while BaAl_2Ti_5O_(14) phase starts to reveal at 1200℃. As the temperature increases, the density, dielectric constant and quality factor of the BaAl_2Ti_5O_(14) ceramic increase and keep unchanged at 1350℃. The dielectric properties of BaAl_2Ti_5O_(14) ceramic sintered at 1350℃ for 3h are: ε_r=35.8, Q×f=5130GHz, τ_f=-6.8ppm/℃.