Crystal Shape Tailoring in Perovskite Structure Rare-Earth Ferrites REFeO3 (RE = La, Pr, Sm, Dy, Er, and Y) and Shape-Dependent Magnetic Properties of YFeO3

Controllable growth of perovskite oxide with tailored shapes is challenging but promising for shape dependent physical and chemical property studies and probable applications. In this article, we report a general method for tailoring the crystal shape of perovskite structure rare-earth ferrite (REFeO3) crystals in hydrothermal conditions. By adjusting the ratio of KOH to urea, various shapes of REFeO3 crystals can be prepared, such as LaFeO3 truncated cubes, PrFeO3 perpendicular cross prisms, SmFeO3 crossed bars with trustum, DyFeO3 double pyramids on cubes, ErFeO3 distorted octahedrons, and YFeO3 long bars and thick hexagonal elongated plates. Detailed shape tailoring conditions for each phase of the crystals have been discussed clearly. The structure-dependent shape growing mechanism for each REFeO3 is generally discussed by consideration of the variance of reduced unit cell parameters in reference to the ideal cubic ABO(3) perovskite structure. DyFeO3 was taken as an example to elucidate the crystal shape formation mechanism based on the Bravais Friedel-Donnay-Harker theory. The magnetic property of the YFeO3 crystal shows shape dependence: elongated bars have the highest saturated magnetization, while the lowest coercive field, while the tailored polyhedrons are vice versa. This paper not only builds a general technique for tailoring the crystal shape to various shapes of REFeO3 crystals but also provides many crystals for further study and application of anisotropy either in physical or in chemical properties.