The Effect of Polyethylene Glycol on the Formation of Bismuth Titanate Nanosheets and Its Effect on Optical Characteristics

Capping agents play a pivotal role in nanoparticle syntheses by providing control over size, morphology, preferred orientation, and crystalline phase. These factors in turn help to enhance and engineer various physical properties of the nanoparticles. This study reveals the role of polyethylene glycol (PEG) in transforming the morphology of bismuth titanate nanospheroids into nanosheets, when varying the amount of this capping agent is added to the precursors during synthesis. PEG-6000 promoted preferential growth along the lateral axis of bismuth titanate to form nanosheets. X-ray diffraction and High-Resolution Transmission Electron Microscopy were used to identify the changes in crystalline structure as well as morphology. The transition of morphology caused the optical absorbance spectra of the nanoparticles to vary, presumably due to misaligned atoms at fringes of the crystallites during the formation of nanosheets. Thermal lensing studies show that the sheet morphology has higher thermal diffusivity.