Size and Morphology Controlled Synthesis of Boehmite Nanoplates and Crystal Growth Mechanisms

Abstract

The aluminum oxyhydroxide boehmite is an important crystalline phase in nature and industry. We report development of a flexible additive-free hydrothermal synthesis method to prepare high quality boehmite nanoplates with sizes ranging from under 20 nm to 5 μm via using hydrated alumina gels and aluminum hydroxide amorphous powders as precursors. The size and morphology of the boehmite nanoplates was systematically varied between hexagonal and rhombic by adjusting precursor concentrations, pH, and the synthesis temperature, due to face-specific effects. The transformation mechanism is consistent with dissolution and reprecipitation, and involves transitory initial appearance of metastable gibbsite that is later consumed upon nucleation of boehmite. Detailed X-ray pair distribution characterization of the solids over time showed similarities in short-range order that suggest linkages in local chemistry and bonding topology between the precursors and product boehmite, yet also that precursor-specific differences in long-range order appear to manifest subtle changes in resulting boehmite characteristics, suggesting that the rate and extent of water release or differences in the resulting solubilized aluminate speciation lead to slightly different polymerization and condensation pathways. The findings suggest that, during dissolution of the precursor, precursor-specific dehydration or solution speciation could be important aspects of the transformation impacting the molecular-level details of boehmite nucleation and growth.

Boehmite@tryptophan‐Pd nanoparticles: A new catalyst for C–C bond formation

“…The XRD pattern of the boehmite@tryptophan‐Pd nanocatalyst is shown in Figure . The peaks at 2 θ values of 14.01°, 18.54°, 20.13°, 24.95°, 28.95°, 41.45°, 47.25°, 53.24°, 55.22°, 59.12°, 64.24° and 68.26° are related to (0 2 0), (1 2 0), (0 3 1), (1 3 1), (0 5 1), (2 0 0), (1 5 1), (0 8 0), (2 3 1), (0 0 2), (1 7 1) and (2 5 1) reflections, respectively, which are in agreement with the standard boehmite XRD pattern . More importantly, the phase of boehmite is not destroyed during the modifications.…”

Short- and Long-Range Mechanical and Chemical Interphases Caused by Interaction of Boehmite (γ-AlOOH) with Anhydride-Cured Epoxy Resins

“…It was suggested that boehmite is produced via the reaction of aluminum ions migrating from the metal, reacting with hydroxyl ions and precipitating back onto the substrate [29]. More recent studies have demonstrated that the size and morphology of crystals can be controlled by variation of precursors, synthesis temperature, time, and pH value [32,33].…”

Pseudoboehmite Nanorod–Polymethylsilsesquioxane Monoliths Formed by Colloidal Gelation

“…Various methods for preparing aluminum oxide hydroxide nanocrystals which can be dispersed in aqueous conditions have been reported. [23][24][25] It is expected that PMSQ-composite porous monoliths with various structures and properties can be prepared using the synthesis method reported in this paper.…”