Hydrothermal synthesis of La1−XSrXMnO3 dendrites

Abstract

Single-crystalline dendrites of La1−XSrXMnO3 (LSMO) perovskite were synthesized using a simple hydrothermal method without the use of surfactants. The Sr2+, La3+, and Mn2+ ions were co-precipitated with aqueous NaOH under a flow of Ar. The aqueous suspension of the precipitates was hydrothermally treated in an autoclave filled with ambient air at temperatures ranging from 220°C to 300°C. The products were characterized using a combination of X-ray diffractometry (XRD) and transmission electron microscopy (TEM, HREM, EDXS). The dendrites formed either in a “tree-like” shape, with the trunk and the branches extending along the 〈111〉 directions of the quasi-cubic structure, or in the hexagonal shape of a “snowflake”. The mechanism of the dendrite nucleation was proposed, based on phase development. During the hydrothermal treatment at lower temperatures the hexagonal platelet crystals of Sr1−XLaXMnO3 with the hexagonal perovskite structure form first. At higher temperatures the LSMO nucleates epitaxially at the edges of the hexagonal crystals and grows outward, forming the dendrite. To the best of our knowledge, this is the first report on the synthesis of crystalline dendrites of La1−XSrXMnO3 perovskite.