Production of submicron Al₂O₃ powders by electrochemical dissolution of aluminum in the presence of nitric acid

A cost-effective and easily scalable method for the synthesis of ultrapure submicron alumina powders with a narrow particle size distribution and high sinterability is proposed. Aqueous solutions of aluminum hydroxide nanoclusters obtained by AC electrochemical dissolution of aluminum metal in the presence of nitric acid were used as a precursor. Hot pressing and vacuum sintering were used to evaluate the possibility of obtaining Al₂O₃ optical ceramics from synthesized powders

Fabrication and study of the strontium fluoroarsenate Sr5(AsO4)3F (SFAs) transparent ceramics

Strontium fluorarsenate Sr5(AsO4)3F optical ceramics were fabricated for the first time by vacuum hot pressing of chemically precipitated powders. The properties of these ceramics were compared with those of the well-known strontium fluorophosphate Sr5(PO4)3F. According to BET, X-ray diffraction, and scanning electron microscopy, Sr5(AsO4)3F and Sr5(PO4)3F powders have an isomorphic single-phase structure and similar particle sizes of about 100–200 nm. The transmittances of 1.5 mm thick samples are as high as 89.5% and 85.8% in the mid-IR for Sr5(AsO4)3F and Sr5(PO4)3F, respectively. The Sr5(AsO4)3F ceramics have a wider mid-IR transmission range (up to 5.8 μm) than the Sr5(PO4)3F ceramics (up to 4.5 μm)

Self-propagating high-temperature synthesis of (Ho1-xLax)2O3 nanopowders for magneto-optical ceramics

Weakly agglomerated nanoparticles of (Ho1-xLax)2O3 solid solutions were synthesized with the help of a self-propagating high-temperature synthesis (SHS). The nanopowders were studied by a simultaneous thermal analysis (TG-DSC), X-ray diffraction (XRD), BET and FT-IR spectroscopy methods. Changes of the particles morphology after annealing at different temperatures and ball milling were investigated by a scanning electron microscopy (SEM) and a dynamic light scattering (DLS) method. It was found that annealing at a temperature of 900 °C in air and ball milling of the SHS nanopowders allow obtaining rounded shape particles with a mean diameter of about 20 nm and C-type cubic crystal structure. Up to 10 mol.% of the lanthana was shown to dissolve in the holmium oxide nanoparticles