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 ABO3 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.