We demonstrate for the first time the crystal growth
of high-entropy
rare-earth (RE) aluminum perovskites (REAlO3) using the
micro-pulling-down method to inform future exploration of functional
crystals. To determine how composition affects phase formation, we
formulate equiatomic compositions containing five REs from the following
list: Lu, Yb, Tm, Er, Y, Ho, Dy, Tb, Gd, Eu, Sm, Nd, Pr, Ce, La. To
test whether combinations of REs with similar ionic radii may favor
a single phase, compositions containing REs with consecutive or nonconsecutive
ionic radius values were formulated. Powder and single-crystal X-ray
diffraction indicate that crystals containing only REs with similar
ionic radii that form orthorhombic single-RE REAlO3 are
a single phase. Crystals containing REs with dissimilar ionic radii
or mixtures of REs that form orthorhombic, rhombohedral, and tetragonal
single-RE REAlO3 are a mixture of phases. The elemental
distribution in single-phase crystals analyzed via electron probe
microanalysis confirms no evidence of preferential incorporation of
any of the constituent REs. The distribution and composition of secondary
phases were analyzed via scanning electron microscopy and energy dispersive
spectroscopy; secondary phases were seen as a small region in the
center of the crystals with branching features closer to the outer
surface.