Gd(5)Si(4-x)P(x): targeted structural changes through increase in valence electron count.
Phase transformations in the Gd(5)Si(4-x)P(x) system (0 <or= x <or= 2), studied through X-ray diffraction techniques, reveal an intimate coupling between the crystal structure and valence electron count. An increase in the valence electron count through P substitution results in breaking the interslab T-T dimers (d(T-T) = 3.74 A; T is a mixture of Si and P) and shear movement of the ( proportional, variant)(2)[Gd(5)T(4)] slabs in Gd(5)Si(2.75)P(1.25). The Gd(5)Si(2.75)P(1.25) phase extends the existence of the orthorhombic Sm(5)Ge(4)-type structures to the valence electron count larger than 31 e(-)/formula unit. Tight-binding linear-muffin-tin-orbital calculations trace the origin of the T-T dimer cleavage in Gd(5)Si(2.75)P(1.25) to a larger population of antibonding states within the dimers.
Svitlyk
Volodymyr
V
Department of Chemistry, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.
Miller
Gordon J
GJ
Mozharivskyj
Yurij
Y