X-Ray and neutron diffraction studies of atomic scale structures of crystalline and amorphous TbFe 2D x

Abstract

Both X-ray and neutron diffraction techniques were employed in order to elucidate short-range structures of crystalline ( c-)TbFe 2D 3.8 and amorphous ( a-)TbFe 2D x ( x=3.0, 2.0) prepared by deuterium absorption of the C15 Laves phase compound TbFe 2. Interatomic distances and coordination numbers were derived from the radial distribution functions, RDF( r)s. The RDF( r)s observed by X-ray diffraction indicated that c-TbFe 2D 3.8 adopts a rhombohedral structure, but there is a little difference in the arrangement of metal atoms between the original C15 Laves phase c-TbFe 2 and the rhombohedral c-TbFe 2D 3.8. In contrast, our results indicated that there is a large difference in the arrangement of metal atoms between c-TbFe 2 and a-TbFe 2D x ( x=3.0, 2.0) and there are clusters of Fe and Tb atoms in a-TbFe 2D x ( x=3.0, 2.0). RDF( r)s observed by the neutron diffraction indicated that the D atoms occupy tetrahedral sites consisting of 2Tb+2Fe in c-TbFe 2D 3.8, while they occupy sites consisting of 4Tb, 3Tb+1Fe and 2Tb+2Fe in a-TbFe 2D x ( x=3.0, 2.0).