Microstructural defects in some rare earth laves phase single crystals

With the extensive research in magnetic behavior of rare earth intermetallic compounds, more specific microstructural characterization on the available single crystals is obviously necessary because many interpretations of the physical property measurements can be particularly dependent on the knowledge of the microstructural defects, impurity distributions, etc. Among the more interesting and also the most extensively investigated rare earth intermetallics are RAl2(R = rare earth elements) compounds, which have the C15 cubic Laves phase structure with the tetrahedra of smaller Al atoms residing at the four corners of the cubic cell. While much effort has been devoted to understanding the nature of the magnetism of RAl2 single crystals by neutron diffraction, e.g. heat capacity measurements, x-ray topography, etc., little work has been performed on characterization of microstructural defects and their effects on physical property measurements. In this work, the authors report a microstructural study on as-grown single crystals of CeAl2 and TbAl2 by transmission electron microscopy (TEM). The presence of (001) growth faults in CeAl2 single crystals and (111) planar defects in TbAl2 single crystals have been identified, and the possible formation mechanism and the influence on the magnetic properties are discussed