Directional metal-hydrogen bonding in interstitial hydrides. III. Structural study of ErCo{sub 3}D {sub x} (0{<=}x{<=}4.3)

Journal Article · Sat Apr 15 00:00:00 EDT 2006 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2006.01.001· OSTI ID:20784955

Filinchuk, Y E ^[1]; Yvon, K ^[1]

---

1. Laboratoire de Cristallographie, Universite de Geneve, 24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland)

The ErCo{sub 3}-D{sub 2} system has been studied by in situ neutron powder diffraction (NPD) at 60 deg. C and 0-16 bar deuterium pressure. Two deuteride phases were identified, {beta}-ErCo{sub 3}D{sub 1.07-1.38} and {gamma}-ErCo{sub 3}D{sub 3.7-4.3}. They were structurally characterized at the compositions {beta}-ErCo{sub 3}D{sub 1.37} and {gamma}-ErCo{sub 3}D{sub 3.7} by high-resolution neutron and synchrotron powder diffraction. In contrast to the analogous nickel systems RNi{sub 3}-D{sub 2} (R=Er, Ho; see part I, J. Alloys and Compds. 404-406 (2005) 89-94, and part II, J. Alloys and Compds. 2005, in press), their structures preserve the symmetry of the parent alloy (PuNi{sub 3}-type, space group R-3m). Deuterium occupies mainly AB{sub 2} building blocks in the {beta}-phase, and AB{sub 2} and AB{sub 5} building blocks in the {gamma}-phase. In the AB{sub 2} building blocks cobalt is surrounded by an average of 3.8 ({beta}-ErCo{sub 3}D{sub 1.37}) and 4.4 D-atoms ({gamma}-ErCo{sub 3}D{sub 3.7}) in disordered distorted octahedral configurations (point symmetry -3), in contrast to nickel that is surrounded by {approx}3 ({beta} {sub 1}- and {beta} {sub 2}-RNi{sub 3}D {sub x} , R=Er, Ho) and {approx}4 ({gamma}-ErNi{sub 3}D{sub 3.7}) D-atoms in disordered trigonal (pyramidal) and tetrahedral configurations, respectively (point symmetry 3). These results indicate that the D-atom distributions in this homologous series depend on the nature of the transition element rather than on geometric factors, and that directional bonding effects similar to those in non-metallic complex transition metal hydrides also prevail in metallic interstitial metal hydrides.

• OSTI ID: 20784955
• Journal Information: Journal of Solid State Chemistry, Vol. 179, Issue 4; Other Information: DOI: 10.1016/j.jssc.2006.01.001; PII: S0022-4596(06)00002-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AXIAL RATIO
CHEMICAL BONDS
COBALT COMPOUNDS
CRYSTAL STRUCTURE
DEUTERIDES
DEUTERIUM
ERBIUM COMPOUNDS
HYDRIDES
HYDROGEN
HYDROGEN STORAGE
NEUTRON DIFFRACTION
SPACE GROUPS