On the Enhanced Solute Content, Shape, Defect Microstructures, and Optical Properties of Ti-Doped γ-Al₂O₃ Nanocondensates

Abstract

The γ-Al2O3 condensates with increased solid solubility (up to ca. 4 atomic %) of Ti, mainly Ti3+ and minor Ti2+/Ti4+ according to X-ray photoelectron spectroscopy, were synthesized by laser ablation condensation in air. Transmission electron microscopy indicated that the nearly spherical condensates were nano- to submicrometer in size having {111} facets for mutual coalescence to form twin or single crystals. The Ti-doped γ-Al2O3 condensates are vulnerable to electron irradiation by forming pits bound by {111}, {110}, and {001} faces with 0, 1, and 2 periodic bond chain in terms of the edge-shared octahedral, respectively, followed by a polygonization or amorphization/recrystallization process. The incorporation of a higher concentration of dopant and the internal stress, as expected via a dynamic process, account for the Raman shift and UV−visible absorbance of Ti-doped γ-Al2O3 for potential optoelectronic applications.