Effect of Temperature on Structural and Optical Properties of Boehmite Nanostructure

The nanocrystalline boehmite, γ‐Al OOH , was synthesized by the hydrothermal method using AlCl ₃ ·6H ₂ O and urea as precursors, and the effect of different annealing temperatures resulting in different phases of alumina (Al ₂ O ₃ ) was obtained. The effects of different temperature on the phase and micrographs of the prepared γ ‐Al OOH nanostructures were investigated. The obtained products were characterized by X‐ray powder diffraction ( XRD ), transmission electron microscopy ( TEM ), Fourier transform infrared spectroscopy ( FTIR ), and Raman spectroscopy techniques. The XRD results show that with the increasing temperature, the transformation of boehmite into well‐crystallized α‐Al ₂ O ₃ and the morphology from nanoplatelets with spindle‐like edges to vermicular structure take place. The crystallite size and lattice parameters were calculated by Rietveld refinement. The convincing evidence for the crystal phase of the as‐prepared and annealed samples was provided by FTIR spectra. The Raman spectra unveil the change in vibrational modes of the phase transition alumina.