Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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W.Wisniewski, M.J.Pitcher, E.Véron, J.Fan, V.Sarou-Kanian, F.Fayon, M.Allix, 'Macroscopic Orientation Domains Grown via Aerodynamic Levitation: A Path toward Single Crystals', Cryst. Growth Des. 21 3554–3561 (2021) doi:10.1021/acs.cgd.1c00350

Powder pellets of ca. 30 mg with the mol % composition 0.61Ga2O30.39La2O3 are levitated in a gas stream and melted using a pair of CO2 lasers. The levitating melt droplets crystallize to form La2Ga3O7.5 or LaGaO3 after the lasers are turned off. The microstructure of cross sections prepared from them is analyzed using scanning electron microscopy and electron backscatter diffraction. One of the beads containing La2Ga3O7.5 shows a fully crystallized, polycrystalline microstructure, whereas the other broke apart during cooling, and its cross section shows only a single orientation domain which is more than 7 mm2 in area. Solid-state 71Ga NMR spectroscopy was applied to this sample and showed that it was not a single crystal but contains only about 3 orientation domains. The bead containing LaGaO3 showed dendritic growth originating from multiple nuclei. Although a single crystal was not achieved by the applied experiments so far, a detailed correlation of measured cooling curves with the observed microstructures enables devising steps along the path toward single crystal production in future experiments.