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Title: Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure

Abstract

The title compound, Ca{sub 2}Pd{sub 3}Ge, was prepared as a part of a systematic investigation of the Ca-Pd-Ge ternary phase diagram. The structure was determined and refined from single-crystal X-ray diffraction data. It is a new fully ordered ternary Laves phase with the space group R-3m, Z=3, a=5.6191 (5) A, c=12.1674 (7) A, wR{sub 2}=0.054 (all data) and is isostructural to Mg{sub 2}Ni{sub 3}Si (Noreus et al., 1985 [17]) but due to the larger size of all elements in Ca{sub 2}Pd{sub 3}Ge, the cell axes are approximately 10% longer. The compound may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The electronic structure and chemical bonding of Ca{sub 2}Pd{sub 3}Ge is discussed in terms of LMTO band structure calculations and compared with CaPd{sub 2} (MgCu{sub 2}-type). - Graphical abstract: The title compound, Ca{sub 2}Pd{sub 3}Ge is a new fully ordered ternary Laves phase which may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The structure is composed of Kagome net layers, consisting of Pd atoms only, which aremore » stacked in an ABC sequence. Band structure calculations show that the Fermi level is located at a local minimum of the DOS (pseudo-gap) indicating that the charge is roughly optimized in the structure. Highlights: Black-Right-Pointing-Pointer Site specific segregation in a Laves phase that is also a Zintl phase. Black-Right-Pointing-Pointer Pseudo-gap at the Fermi level in a Laves phase. Black-Right-Pointing-Pointer Distorted Frank-Kasper polyhedron.« less

Authors:
 [1]; ;  [1]
  1. Centre for Analysis and Synthesis, Lund University, P.O. Box 124, 22100 Lund (Sweden)
Publication Date:
OSTI Identifier:
22131192
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 197; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CATIONS; CHEMICAL BONDS; ELECTRONIC STRUCTURE; FERMI LEVEL; LAVES PHASES; LAYERS; MONOCRYSTALS; PHASE DIAGRAMS; SPACE GROUPS; X-RAY DIFFRACTION

Citation Formats

Doverbratt, Isa, E-mail: isa.doverbratt@polymat.lth.se, Ponou, Simeon, and Lidin, Sven. Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure. United States: N. p., 2013. Web. doi:10.1016/J.JSSC.2012.09.003.
Doverbratt, Isa, E-mail: isa.doverbratt@polymat.lth.se, Ponou, Simeon, & Lidin, Sven. Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure. United States. doi:10.1016/J.JSSC.2012.09.003.
Doverbratt, Isa, E-mail: isa.doverbratt@polymat.lth.se, Ponou, Simeon, and Lidin, Sven. Tue . "Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure". United States. doi:10.1016/J.JSSC.2012.09.003.
@article{osti_22131192,
title = {Ca{sub 2}Pd{sub 3}Ge, a new fully ordered ternary Laves phase structure},
author = {Doverbratt, Isa, E-mail: isa.doverbratt@polymat.lth.se and Ponou, Simeon and Lidin, Sven},
abstractNote = {The title compound, Ca{sub 2}Pd{sub 3}Ge, was prepared as a part of a systematic investigation of the Ca-Pd-Ge ternary phase diagram. The structure was determined and refined from single-crystal X-ray diffraction data. It is a new fully ordered ternary Laves phase with the space group R-3m, Z=3, a=5.6191 (5) A, c=12.1674 (7) A, wR{sub 2}=0.054 (all data) and is isostructural to Mg{sub 2}Ni{sub 3}Si (Noreus et al., 1985 [17]) but due to the larger size of all elements in Ca{sub 2}Pd{sub 3}Ge, the cell axes are approximately 10% longer. The compound may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The electronic structure and chemical bonding of Ca{sub 2}Pd{sub 3}Ge is discussed in terms of LMTO band structure calculations and compared with CaPd{sub 2} (MgCu{sub 2}-type). - Graphical abstract: The title compound, Ca{sub 2}Pd{sub 3}Ge is a new fully ordered ternary Laves phase which may formally be considered as a Zintl compound, with [Pd{sub 3}Ge]{sup 4-} forming a poly-anionic network and divalent Ca cations located in truncated tetrahedral interstices. The structure is composed of Kagome net layers, consisting of Pd atoms only, which are stacked in an ABC sequence. Band structure calculations show that the Fermi level is located at a local minimum of the DOS (pseudo-gap) indicating that the charge is roughly optimized in the structure. Highlights: Black-Right-Pointing-Pointer Site specific segregation in a Laves phase that is also a Zintl phase. Black-Right-Pointing-Pointer Pseudo-gap at the Fermi level in a Laves phase. Black-Right-Pointing-Pointer Distorted Frank-Kasper polyhedron.},
doi = {10.1016/J.JSSC.2012.09.003},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 197,
place = {United States},
year = {Tue Jan 15 00:00:00 EST 2013},
month = {Tue Jan 15 00:00:00 EST 2013}
}