Mechanochemical activation assisted synthesis of bismuth Layered-Perovskite Bi4Ti4O12

A powder mixture of Bi2O3 and TiO2, both monoclinic, was mechanochemically treated in a planetary ball mill in air atmosphere for different time, using zirconium balls as the milling medium. Mechanochemical reaction leads to the gradual formation of an amorphous phase. After 1 h of milling the starting oxides were transformed fully a nanocrystalline Bi4Ti4O12 phase. With increasing the milling time from 3 to 12h, the particle size of formed Bi4Ti3O12 did not reduced significantly. That was confirmed by IR and TEM analysis. The electron diffraction pattern indicates that Bi4Ti3O12 crystalline powder is embedded in an amorphous phase of bismuth titanate. Phase composition and atom ratio in BIT ceramics were determined by X-ray diffraction and EDS analysis. After milling for various times the powders were compacted by pressing and isothermal sintering. The dielectric permittivity of the sintered samples significantly depends on the milling time. Sample milled for 12 h and subsequently sintered at 1000°C for 24 h exhibit a hysteresis loop, confirming that the synthesized material possesses ferroelectric properties