Crystalline lanthanum hydroxycarbonates with controlled phases and varied morphologies prepared on non-crystalline substrates

Abstract

Lanthanum hydroxycarbonate crystals with controlled phases and varied morphologies were prepared on the surface of a non-crystalline substrate, glass. The phases and morphologies of the crystals were controlled conveniently by varying the reaction temperature and the quantity of starting materials. Orthorhombic crystals were obtained at 160°C, distributed individually on the substrate and had a flaky rhombic shape. Hexagonal crystals were obtained at 180°C. The crystals had a rhomboidal shape, were uniform and continuous enough to form a solid film on the substrate. The substrates were corroded under the hydrothermal conditions and offered a coarse surface for the crystal growth. The hexagonal lanthanum hydroxycarbonate was discovered to show significant second harmonic generation, which would be of interest for developing novel optical materials. Crystalline LaOHCO 3 were prepared on common non-crystalline glass. Orthorhombic phase and hexagonal phase were obtained at different temperatures, made up of flaky crystals and rhomboidal crystals, respectively. The hexagonal crystals grown on the glass are compact enough to form a solid film, which shows second harmonic generation. © 2004 Elsevier Inc. All rights reserved.