Low-temperature synthesis of bismuth titanate by an aqueous sol-gel method

Homogeneous and fine bismuth titanate (BIT) nanoplate-like powders were synthesized by a modified and simple sol-gel method. The thermal gravimetry-differential thermal analysisderivative differential thermal analysis indicated that BIT gel decomposes in two steps posited at approximately 278° and 432°C, and BIT began to crystallize before 450°C. Based on the high-temperature X-ray diffraction results, it was concluded that the crystallization temperature of BIT synthesized by the present method was about 425°C and there was no evidence of the formation of an intermediate phase. The BIT crystal structure belonged to the orthorhombic phase with lattice parameters a=5.420 A°, b=5.431 A°, and c=33.273 A°. Field emissionscanning electron microscopy revealed that fine and uniform BIT nanoplate-like powders, about 30 nm in size, were obtained after sintering at 500°C. With increasing temperature, the BIT grains rapidly grew and the coalescence of adjacent grains took place. The synthesis temperatures adopted were substantially lower than those reported in the other literatures.