Journal of the American Ceramic Society · 1992 · 210 citations · 3 references
Natural SciencesChemistryMaterials ScienceInorganic ChemistryPhysical ChemistrySolid-state ChemistryAluminum HydroxidesAluminum OxidesCrystallization ProcessesAqueous Salt SolutionsConcentrationHydrothermal Crystal GrowthHydrothermal ProcessingHydrothermal SynthesisHydrothermal Synthesis Of Metal Oxide NanomaterialsHydrothermal TreatmentSupercritical Fluids
AlOOH particles were synthesized hydrothermally from an Al(NO₃)₃ solution in subcritical and supercritical water, with continuous rapid production achieved by mixing the solution with preheated water, and the influence of temperature, pressure, and concentration on particle size, morphology, and crystal structure was investigated. Particle size, morphology, and crystal structure are strongly affected by slight changes in pressure and temperature near the critical point, enabling simultaneous control of these properties in supercritical water.
Hydrothermal synthesis of AlOOH particles from an Al(NO 3 ) 3 aqueous solution was examined in subcritical and supercritical water. Continuous and rapid production of AlOOH fine particles was achieved by mixing a metal salt aqueous solution with preheated water fed from another line. The effects of temperature, pressure, and initial concentration of solution on the particle size, morphology, and crystal structure of the metal (hydrous) oxides were examined. These properties are strongly affected by slight changes in pressure and temperature. This strong effect is attributed to the large changes in the properties of water near its critical point resulting from the slight changes in pressure and temperature. The results suggest the simultaneous control of size, crystal structure, and morphology of the particles by hydrothermal synthesis in supercritical water.
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