In this work, mesoporous spherical γ-AlOOH and γ-Al2O3 particles were rapidly prepared by spray pyrolysis (SP) at different temperatures (400°C–700°C) without the use of template materials. A sol-gel-derived colloidal solution boehmite was ultrasonicated to generate fine droplets, which continuously transferred into a quartz reactor heated specific temperature constant flow N2 gas. Under ultras...

Colloidal gels respond as soft solids at rest, whereas they flow liquids under external shear. Starting from a fluidized state an applied shear rate ${\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\gamma}}}_{p}$, abrupt cessation triggers liquid-to-solid transition during which the stress relaxes towards so-called residual ${\ensuremath{\sigma}}_{\mathrm{res}}$ that tallies macroscopic ...

In this work, we study three aluminum oxides (alpha, gamma, boehmite) and various oxidized metallic powders to observe their dehydration decomposition behavior using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) scanning electron microscopy (SEM). We find that a temperature increase the (aluminas) reduces physically adsorbed water molecules reveal presence of hydr...

Corundum primary deposits in Greece occur four locations: Paranesti Drama and Gorgona Xanthi, both belonging to the wider Rhodope Massif, as well as, Ikaria island Kinidaros Naxos island, Attic-Cycladic Massif. Eight samples were examined with spectroscopic methods (FTIR, UV-Vis, EDXRF) order better characterize these deposits: two pink sapphires from Paranesti, a blue sapphire Gorgona, three K...