Long period stacking order in close packed structures of metals

摘要: Abstract The origin of the stabilization close packed structures with periodic stacking order in relation to specific shape Fermi surface is investigated. For this purpose, crystal Au-Mn alloys between 20 and 28% Mn have been analyzed systematically. these are quite sensitive a change composition each specimen invariably includes several which make usage electron microscopes indispensible for analysis. application systematic analysis crystallographic thus explored method identifying their relations then established. This allows us identify all existing range unambiguously. identified are: Au 4 at around 20% Mn; ∝″(the two-dimensional long period superlattice 3 Mn, first single thin films) 21–22% series 23 direct interest here. These latter modulations M = 1 (a one-dimensional antiphase boundaries Cu type unit cell, often referred as DO2 2 ), can be specified R (the original structure 6 layers structural period), 5 H (10 layers), (18 layers) (both layers). Although varying amounts coexist specimens over range, statistical appearance increasing content → (6 coexisting unmodulated > 1(1 ) most noticeably structures. size modulated indicates that created shift Brillouin zone proper places when (or electron-atom ratio) deviates from exact value stabilizes structure. In other words, modulation an effort create reduce energy electrons. It concluded respect origin, belong same category superlattice, “stacking fault boundaries” are, like “antiphase form low boundary enables become more stable than case structure, symmetry basal plane by slip amount l 6a〈112〉 without destroying degree order. Thus makes favorable. Remarks made concerning applicability explanations metallic systems.