Campus Units

Chemistry, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

2016

Journal or Book Title

Inorganic Chemistry

Volume

55

First Page

5041

Last Page

5050

DOI

10.1021/acs.inorgchem.6b00612

Abstract

Cluster chemistry of intermetallics with valence electron counts (VECs) in the range of 2.0–3.0 is intriguing. Lithiation of polar intermetallics in this VEC region is found to be an effective chemical route to produce new complex structures with different stability mechanisms. In this work, two new complex intermetallic structures have been discovered in the Ca–Li–Zn system: Ca12LixZn59–xand Ca15LixZn75–x. Ca12LixZn59–x, x ≈ 5.65(3)–14.95(3), forms in the trigonal space group Rm, with a = 9.074(1)–9.1699(2) Å, c = 53.353(1)–53.602(1) Å, and Z = 3. In comparison, Ca15LixZn75–x, x ≈ 19.07(2), crystallizes in the space group P63/mmc, with a ≈ 9.183(1) Å, c ≈ 45.191(5) Å), and Z = 2. Both structures are members of a large intergrowth family featuring slabs of dimers (D) and trimers (T) stacking along [001], with the sequences DTDDTDDTD for Ca12LixZn59–x and TDDDTDDD for Ca15LixZn75–x. Each dimer consists of two face-sharing Zn-centered hypho-icosahedra, and each trimer comprises a Li-centered icosahedron sandwiched by two hypho-icosahedra. This intergrowth family includes several known intermetallic structure types involving very electropositive metals, e.g., SrMg5.2, Ba2Li4.21Al4.79, and Sr9Li17.5Al25.5. Because of cluster defects and condensation, both Ca12LixZn59–x and Ca15LixZn75–x are electronically akin to close-packed metals, and their structural stabilities can be interpreted by a Hume-Rothery mechanism rather than the Zintl–Klemm concept.

Comments

This is an article from Inorganic Chemistry 55 (2016): 5041, doi: 10.1021/acs.inorgchem.6b00612. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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