Preparation and Characterization of Different Phases of Aluminum Trifluoride

Abstract

Several phases (α, ε2, and γ) of aluminum fluoride were prepared from precursors such as NH4AlF4, (NH4)3AlF6, and β-AlF3·3H2O using various synthetic strategies. The precursors and the aluminum fluoride phases obtained were characterized by X-ray diffraction (XRD), X-ray fluorescence, scanning electron microscopy (SEM), and infrared spectra (FT-IR). The structural evolution of the precursors to the different phases of aluminum fluoride during thermal treatment was studied by dynamic XRD experiments, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). α- and γ-AlF3 phases were obtained with high BET surface areas (>120 and 30 m2/g, respectively). These aluminum fluorides with high BET areas are of potential interest as supports or catalysts in hydrodechlorination and fluorination reactions.

Patterned aluminum nanowires produced by electron beam at the surfaces of AlF3 single crystals

“…3). These results differ from the morphology previously reported by other groups who have synthesized a-AlF 3 through plasma-assisted fluorination reaction with nitrogen trifluoride [11] and thermal decomposition of hexafluoroaluminate [13]. In those studies, porous a-AlF 3 was synthesized and the surface morphology is rather rough.…”

“…The as-deposited material was characterized and analyzed by X-ray diffraction (XRD: Philips PW 1800 with Cu Ka radiation) and scanning electron microscopy (SEM: LEO 1530 FEG). Since AlF 3 has several phases, it is essential to determine the phase of the as-produced AlF 3 by XRD [13]. An examination of the sample with XRD indicates that it has a rhombohedral crystal structure with space group R 3(148) (Fig.…”

Hydrated cement: A promising adsorbent for the removal of fluoride from aqueous solution

“…2a that the SEM micrographs of the HC before treatment of F − shows irregularly shaped particles with surface agglomerates of small size particles adhered on bigger particles while the SEM micrographs (Fig. 2b) of the HC after treatment of F − shows nearly octahedral and stretched cubic structures which may be formed by the precipitation of aluminum and calcium salts (F − ) [13][14][15]. In order to know the chemical composition, chemical analysis of HC was carried out by weight percentage which is expressed in terms of oxides as Al 2 O 3 (3.70%), Fe 2 O 3 (3.65%), SiO 2 (17.44%), CaO (51.21%), and MgO (0.73%).…”

Fluorinated transition alumina with Al2−x/3O3−xFx compositions: Thermal, chemical, structural and morphological investigations

“…The thermal stability of aluminium fluorides has been generally investigated in an inert atmosphere avoiding any pyrohydrolysis process aiming for the identification of new fluoride phases [21] or phase transformations [22][23][24]. Therefore, to our knowledge, no investigation has dealt in detail with the thermal transformation of anhydrous AlF 3 under air atmosphere.…”