Preparation of Bi4Ti3O12 Thick Films by Screen Printing

Bi₄Ti₃O₁₂ (BIT) thick films have been successfully prepared on Pt/ZrO₂ substrates by the screen printing technique. Pt bottom and Ag top electrodes were also fabricated at 1300degC for 1 h and 850degC for 10 min by screen printing pastes, respectively. The influence of excess Bi₂O₃ as a sintering aid was investigated in this study. Screen printable pastes were prepared by kneading appropriated proportions of Bi₄Ti₃O₁₂ and excess Bi₂O₃ powders in a three-roll mill with an organic vehicle consisting of ethyl cellulose and alpha-terpineol. After screen-printing the ferroelectric paste using a 200-mesh screen mask, printed BIT films were allowed to level for 10 min and then dried at 130degC for 10 min. These BIT films were sintered at 1100 degC for 80 min. These processes from printing to sintering were repeated three times to obtain ferroelectric BIT films of 39 mum thickness. The microstructures, ferroelectric and dielectric properties of the BIT thick films were examined as a function of excess Bi₂O₃ additives in the ranges from 0 to 20 wt%. The maximum value of the dielectric constant was obtained at Bi₂O₃ additives of 10wt% and its value was 165 at room temperature. The remanent polarization P_r of 10muC/cm² and coercive field E_c of 38kV/cm were also obtained at the Bi₂O₃ of 10wt%.