Formation of bayerite, gibbsite and boehmite particles by laser ablation

Abstract

Aluminium hydroxides were prepared by the laser ablation method, a nanosecond pulsed laser being employed to irradiate an Al rod immersed in H₂O solvent. Through the course of aging, bayerite, gibbsite and boehmite particles were formed simultaneously. These crystals exhibited three different morphologies. Their shapes were triangular (bayerite), rectangular (gibbsite) and fibrous (boehmite). The dimensions averaged several hundred nanometers. The measurements of the UV-vis absorption can serve as a tool to identify whether or not the crystalline particles had been obtained, in addition to the TEM images. A dissolution–recrystallization process was observed in the development of aluminous materials. The progression of formation from bulk Al to nano-aluminium hydroxides is discussed. Both basic and acidic conditions showed an influence on the growth of particles. The boehmite products can be generated solely by increasing the solution temperature.