The formation and microstructural properties of uniform alpha-GaOOH particles and their calcination products

摘要

Uniform alpha-GaOOH submicron particles of different shapes (spindles, rhombic rods, rhombic prisms, hierarchical particles) were synthesized by simple low-temperature (at 60 degrees C) or hydrothermal (at 160 degrees C) precipitation from the mixture of aqueous solutions of gallium(III) chloride and organic alkali tetramethylammonium hydroxide (TMAH) at various pH values (5, 7 or 9). The growth mechanism of these particles was discussed. Crystallographic directions and crystal planes in alpha-GaOOH particles were identified. Differences in crystallite size, thermal and infrared properties of alpha-GaOOH particles were observed and discussed. Uniform alpha-Ga2O3 and beta-Ga2O3 particles of the same or similar shapes, containing holes due to dehydroxylation, were obtained by calcination of the corresponding alpha-GaOOH particles at 500 or 900 degrees C, respectively. Differences in crystallite size and infrared properties of obtained gallium oxide samples, as well as differences in photoluminescence properties of beta-Ga2O3 samples were observed and discussed. (C) 2014 Elsevier B.V. All rights reserved.