Novel simple methods for the synthesis of single-phase valentinite Sb2O3

Several methods with solid and dissolved reactants were investigated as possible routes for synthesis of single-phase valentinite Sb₂O₃. The methods are based on simple chemical reaction between SbCl₃ and NaOH. The method with solid state reactants was established on self-propagating room temperature reaction (SPRT), while wet syntheses were based on the same chemical reaction, and performed in either distilled water or absolute ethanol. The prepared powders were characterized by X-ray powder diffraction, scanning electron microscopy and field emission scanning electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction (SAED) and UV/vis diffuse reflectance spectroscopy. SPRT and aqueous solution syntheses resulted in single-phase valentinite Sb₂O₃, but with significantly different morphologies. In the case of SPRT method the obtained powder contains well crystallized prismatic shaped submicronic particles, with hexagonal or lozenge basis typical for valentinite crystal structure, while aqueous solution synthesis resulted in powder containing micronic agglomerates. The ethanolic solution synthesis product was Sb₂O₃ with cubic senarmontite as predominant phase and traces of orthorhombic valentinite. It was confirmed that not only the aggregate state, but also the choice of solvent has a great influence on the structural and optical characteristics of synthesized Sb₂O₃ powders.