Synthesis and Crystal Structure Determinations in the Γ and δ Phase Domains of the Iron–Zinc System: Electronic and Bonding Analysis of Fe13Zn39 and FeZn10, a Subtle Deviation from the Hume–Rothery Standard?

✍ Scribed by Claude H.E. Belin; Renaud C.H. Belin

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 581 KB
• Volume: 151
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8626

✦ Synopsis

The iron+zinc system has been investigated in the zinc-rich domain. Alloying of Fe and Zn in ZnCl 2 6ux allowed the formation of well-developed single crystals of phases Fe 13 Zn 39 and FeZn 10 in a one-step experiment. These phases crystallize in cubic space group I4 3m ( ) phase, Fe 13 Zn 39 , a ‫؍‬ 8.994(2) A > , Z ‫؍‬ 1) and in the hexagonal space group P6 3 /mmc ( phase, FeZn 10 , a ‫؍‬ 12.787(3) A > , c ‫؍‬ 57.222(7), c/a ‫؍‬ 4.475 A > , Z&50). The structure of Fe 13 Zn 39 was reinvestigated and re5ned to R(F) of 3.28%; it is of the cubic Cu 5 Zn 8 type. Its three-dimensional network is composed of fused tetrahedra of icosahedra (Fe/Zn) centered by Fe atoms. Fe/Zn occupational disorder has been accurately determined. The huge hexagonal structure of FeZn 10 (c.a., Fe 1.04(1) Zn 10 ) has been determined for the 5rst time and re5ned to R(F) of 6.84%. It contains 52 Fe and 504 Zn atoms and consists of a very dense packing of icosahedra and a few other polyhedra. Among the 52 independent atoms in the unit cell, seven atoms describe a disordered icosahedron spinning around a three-fold axis. Electronic properties are analyzed on the basis of tight-binding extended HuK ckel band calculations. The relationship of metallic bonding to clustering within the Fe 13 Zn 39 phase has also been investigated using some electronic requirements for polyhedral condensation.