Radial Distribution Function of an Amorphous Mn–P–C Alloy

An amorphous manganese base alloy having the composition Mn0.75P0.15C0.10 was synthesized by rapid quenching from the liquid state. Its structure was studied using x-ray diffraction. The interference function a(K) of this alloy is characterized by a shoulder on the high-angle side of the second peak, a feature which has been previously observed in several other amorphous alloys but not in amorphous Ni–Pt–P. Both the atomic distribution function W(r) as well as the radial distribution function (RDF) [=4πr2ρ(r)] contain a split double peak beyond the first maximum. The radius of the first near-neighbor shell is 2.63 Å, and its coordination number is approximately 12. The ratio of second to first near-neighbor average interatomic distance is 1.7. A structural model based upon ``dense random packing'' of Mn atoms with the metalloids P and C filling up some of the interstices may be appropriate for this alloy.