Laser ablation of gallium metal was performed to prepare spindle-like GaOOH particles in aqueous solution. Formation of well-defined GaOOH was strongly associated with the addition of cationic CTAB surfactant. It was found that spindle-like GaOOH could be grown in below, near, or above critical micelle concentrations (cmc) of CTAB via an aging process. On the other hand, using anionic SDS surfactant or pure H2O solvent could not exclusively give the final spindle-like GaOOH, but the irregular and amorphous materials were produced. TEM, XRD, FT-IR, SEM, XPS, ζ-potential, and 1H NMR measurements were carried out to characterize the resulting precipitates. High-resolution TEM indicated that GaOOH crystals formed a type of layered structure and grew along the 〈001〉 axis. Without the presence of the surfactants, the nascent colloidal solutions, immediately after laser ablation, were prepared for the ζ-potential measurements. The negative sign of ζ-potential for the laser-ablated surfactant-free colloids indicates that the cationic CTAB would preferentially adsorb onto the colloidal negative surface. It is proposed that the adsorption of the CTAB might have facilitated the development of the ellipsoidal nanocrystals through a slow crystallization process. Calcination of these gallium oxide hydroxides at a temperature of 750°C (18 h) transformed into β-Ga2O3, but following a stepwise pathway, i.e., 250°C (64 h) → 250°C (64 h) → 750°C (18 h), converted as α-Ga2O3.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry