skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn 2-xPd x

Abstract

A series of pseudo-binary compounds MgZn 2-xPd x (0.15 ≤ x ≤ 1.0) were synthesized and structurally characterized to understand the role of valence electron concentration (vec) on the prototype Laves phase MgZn 2 with Pd-substitution. Three distinctive phase regions were observed with respect to Pd content, all exhibiting fundamental Laves phase structures: 0.1 ≤ x ≤ 0.3 (MgNi 2-type, hP24; MgZn 1.80Pd 0.20(2)), 0.4 ≤ x ≤ 0.6 (MgCu 2-type, cF24; MgZn 1.59Pd 0.41(2)), and 0.62 ≤ x ≤ 0.8 (MgZn 2-type, hP12: MgZn 1.37Pd 0.63(2)). Refinements from single-crystal X-ray diffraction indicated nearly statistical distributions of Pd and Zn atoms among the majority atom sites in these structures. Interestingly, the MgZn 2-type structure re-emerges in MgZn 2–xPd x at x ≈ 0.7 with the refined composition MgZn 1.37(2)Pd 0.63 and a c/a ratio of 1.59 compared to 1.64 for binary MgZn 2. Electronic structure calculations on a model “MgZn 1.25Pd 0.75” yielded a density of states (DOS) curve showing enhancement of a pseudogap at the Fermi level as a result of electronic stabilization due to the Pd addition. Moreover, integrated crystal orbital Hamilton population values show significant increases of orbital interactions for (Zn,Pd)–(Zn,Pd) atom pairs within the majority atommore » substructure, i.e., within the Kagomé nets as well as between a Kagomé net and an apical site, from binary MgZn 2 to the ternary “MgZn 1.25Pd 0.75”. Multi-centered bonding is evident from electron localization function plots for “MgZn 1.25Pd 0.75”, an outcome which is in accordance with analysis of other Laves phases.« less

Authors:
 [1];  [1]
  1. Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1221935
Report Number(s):
IS-J-8752
Journal ID: ISSN 0044-2313
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Zeitschrift fuer Anorganische und Allgemeine Chemie
Additional Journal Information:
Journal Volume: 641; Journal Issue: 8-9; Journal ID: ISSN 0044-2313
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Laves phase; X-ray diffraction; single crystal diffraction; structure determination; electronic structure

Citation Formats

Thimmaiah, Srinivasa, and Miller, Gordon J. Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn2-xPdx. United States: N. p., 2015. Web. doi:10.1002/zaac.201500197.
Thimmaiah, Srinivasa, & Miller, Gordon J. Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn2-xPdx. United States. doi:10.1002/zaac.201500197.
Thimmaiah, Srinivasa, and Miller, Gordon J. Wed . "Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn2-xPdx". United States. doi:10.1002/zaac.201500197. https://www.osti.gov/servlets/purl/1221935.
@article{osti_1221935,
title = {Influence of valence electron concentration on Laves phases: Structures and phase stability of pseudo-binary MgZn2-xPdx},
author = {Thimmaiah, Srinivasa and Miller, Gordon J.},
abstractNote = {A series of pseudo-binary compounds MgZn2-xPdx (0.15 ≤ x ≤ 1.0) were synthesized and structurally characterized to understand the role of valence electron concentration (vec) on the prototype Laves phase MgZn2 with Pd-substitution. Three distinctive phase regions were observed with respect to Pd content, all exhibiting fundamental Laves phase structures: 0.1 ≤ x ≤ 0.3 (MgNi2-type, hP24; MgZn1.80Pd0.20(2)), 0.4 ≤ x ≤ 0.6 (MgCu2-type, cF24; MgZn1.59Pd0.41(2)), and 0.62 ≤ x ≤ 0.8 (MgZn2-type, hP12: MgZn1.37Pd0.63(2)). Refinements from single-crystal X-ray diffraction indicated nearly statistical distributions of Pd and Zn atoms among the majority atom sites in these structures. Interestingly, the MgZn2-type structure re-emerges in MgZn2–xPdx at x ≈ 0.7 with the refined composition MgZn1.37(2)Pd0.63 and a c/a ratio of 1.59 compared to 1.64 for binary MgZn2. Electronic structure calculations on a model “MgZn1.25Pd0.75” yielded a density of states (DOS) curve showing enhancement of a pseudogap at the Fermi level as a result of electronic stabilization due to the Pd addition. Moreover, integrated crystal orbital Hamilton population values show significant increases of orbital interactions for (Zn,Pd)–(Zn,Pd) atom pairs within the majority atom substructure, i.e., within the Kagomé nets as well as between a Kagomé net and an apical site, from binary MgZn2 to the ternary “MgZn1.25Pd0.75”. Multi-centered bonding is evident from electron localization function plots for “MgZn1.25Pd0.75”, an outcome which is in accordance with analysis of other Laves phases.},
doi = {10.1002/zaac.201500197},
journal = {Zeitschrift fuer Anorganische und Allgemeine Chemie},
number = 8-9,
volume = 641,
place = {United States},
year = {2015},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

Save / Share: