The Crystal Chemistry and Physics of Metals and Alloys

Atomic structure of the i-R-Cd quasicrystals and consequences for magnetism

“…Here the δ was calculated using the atomic radii listed in Ref. 38. Interestingly, whereas the structural refinement of the i-YbCd 5.7 quasicrystal shows full occupancy of the R icosahedron shell, 6 a recent 6-D structural refinement for i-ScZn 7.33 also indicates the possibility of site disorder on the icosahedron shell with the ratio of Zn/Sc = 26/74.…”

Simple metal and binary alloy phases based on the hcp structure: Electronic origin of distortions and superlattices

“…As was discussed by Pearson (see Ref. [12], p.231), the higher empty d-states may participate with the s and p valence states of group V elements and this transference "can be accounted for the degree of filling of bond orbitals by valence electrons". Within our model only sp electron are considered for the FS formation, and the effective number of valence electrons for Sb is assumed as 4, giving for Cu 10 Sb 3 the average number z ~ 1.7.…”

“…The stability of the complex structures of alkali metals on pressure increase can be related to the Hume-Rothery mechanism assuming an electron transition from core-to-valence band as suggested for sodium in the oP8 structure [11]. This phase is structurally identical to some of the binary phases, as for example the AuGa-oP8 with 2 electrons per atom [12]. Therefore an analysis of structural relations for binary phases and mechanisms of the distortion from high symmetry metallic phases may help to understand the origin of complexity in compressed elements.…”

“…[12] pp.120-121).These phases show a characteristic variation of the axial ratio with the electron concentration per atom deviating from the ideal value c/a= 3 / 8 =1.633. We consider c/a variations in relation to FS-BZ configurations.…”

“…It is necessary to take into account the difference in the atomic size for Cu and Sb (1.28 Ǻ and 1.59 Ǻ, respectively (see Ref. [12], p.151). Due to size difference of about 25% there are emerged effects of "chemical" pressure in the formation of Cu-Sb alloys, resulting in some changes of valence electron configuration for Sb.…”