Shape tuneable synthesis of perovskite structured rare-earth chromites RECrO3via a mild hydrothermal method

Abstract

Controllable synthesis of perovskite structured oxides with well-defined facets is a challenging but important route for crystal shape and facet dependent applications. In this paper, we report a urea-modified hydrothermal method for shape tuneable growth of perovskite structured rare-earth chromite (RECrO₃) crystals. By adjusting the concentration of urea, continuous shape evolution processes of LaCrO₃, PrCrO₃ and NdCrO₃ were found, such as transformation of LaCrO₃ from cubic to truncated cubic and spherical crystals, PrCrO₃ from pseudo-cubic to truncated parallelepiped plate twin crystals, and NdCrO₃ from parallelepiped plates to their truncated analogues. The shape formation mechanism of each RECrO₃ has been generally discussed by considering their structures and the interactions between the crystal facets and shape directing agents. The crystal facet formation mechanism of RECrO₃ crystals follows the Bravais–Friedel–Donnay–Harker theory. This paper provides a general shape controllable growth technique for RECrO₃ crystals, which is important for further study and application of their anisotropic properties.