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

An amorphous manganese base alloy having the composition Mn_(0.75)P_(0.15)C_(0.10) 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) [= 411'Y2p(r)) contain a split double peak beyond the first maximum. The radius of the first near-neighbor shell is 2. 63 A, and its coordination number is approximately 12. The ratio of second to first near-neighbor average interatomic distances 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.