Advanced

On a TiNiSi-Type Superstructure: Synthesis, Crystal and Electronic Structures of CaAgGe and Its Mn-Substituted Derivative

Ponou, Simeon LU (2010) In European Journal of Inorganic Chemistry p.4139-4147
Abstract
The compound CaAgGe and its Mn-substituted derivative CaMn0.07Ag0.93Ge were synthesized by reaction of the element mixtures at high temperature. Their structures were refined from single-crystal X-ray diffraction data. CaAgGe crystallizes in the isomorphic (i(3)) superstructure of the TiNiSi type (CaCuGe type). The LMTO band structure calculations predicted the CaAgGe phase to be metallic. In addition, it appeared that the valence electron concentration is critical for the atomic ordering and the resulting superstructure. Thus, CaAgGe is one electron short per asymmetric unit, but a drastic narrowing of the electron shortage is achieved through the more complex atomic ordering in the supercell, relative to the simple TiNiSi type subcell.... (More)
The compound CaAgGe and its Mn-substituted derivative CaMn0.07Ag0.93Ge were synthesized by reaction of the element mixtures at high temperature. Their structures were refined from single-crystal X-ray diffraction data. CaAgGe crystallizes in the isomorphic (i(3)) superstructure of the TiNiSi type (CaCuGe type). The LMTO band structure calculations predicted the CaAgGe phase to be metallic. In addition, it appeared that the valence electron concentration is critical for the atomic ordering and the resulting superstructure. Thus, CaAgGe is one electron short per asymmetric unit, but a drastic narrowing of the electron shortage is achieved through the more complex atomic ordering in the supercell, relative to the simple TiNiSi type subcell. This results in the formation of (Ge-2) dumbbells in the supercell, which ascribe greater electronic flexibility to the structure. Despite the fact that CaAgGe is not a Zintl phase in the strict definition as valence balanced intrinsic semiconductor, its structural aspects and transport properties can still be understood within the Zintl concept. The formal Zintl phase Ca3MnAg2Ge3 could be predicted from the theoretical calculations, but no significant phase width was observed experimentally in the substituted derivative Ca3Mn0.21Ag2.79Ge3. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
superstructure, TiNiSi-type, Zintl phases, Solid-state structures, Intermetallic phases
in
European Journal of Inorganic Chemistry
issue
26
pages
4139 - 4147
publisher
John Wiley & Sons
external identifiers
  • wos:000282913300010
  • scopus:77956604981
ISSN
1099-0682
DOI
10.1002/ejic.201000439
language
English
LU publication?
yes
id
1eda747c-6373-4238-9996-c3945777e47c (old id 1726116)
date added to LUP
2010-12-06 10:57:06
date last changed
2018-05-29 10:03:31
@article{1eda747c-6373-4238-9996-c3945777e47c,
  abstract     = {The compound CaAgGe and its Mn-substituted derivative CaMn0.07Ag0.93Ge were synthesized by reaction of the element mixtures at high temperature. Their structures were refined from single-crystal X-ray diffraction data. CaAgGe crystallizes in the isomorphic (i(3)) superstructure of the TiNiSi type (CaCuGe type). The LMTO band structure calculations predicted the CaAgGe phase to be metallic. In addition, it appeared that the valence electron concentration is critical for the atomic ordering and the resulting superstructure. Thus, CaAgGe is one electron short per asymmetric unit, but a drastic narrowing of the electron shortage is achieved through the more complex atomic ordering in the supercell, relative to the simple TiNiSi type subcell. This results in the formation of (Ge-2) dumbbells in the supercell, which ascribe greater electronic flexibility to the structure. Despite the fact that CaAgGe is not a Zintl phase in the strict definition as valence balanced intrinsic semiconductor, its structural aspects and transport properties can still be understood within the Zintl concept. The formal Zintl phase Ca3MnAg2Ge3 could be predicted from the theoretical calculations, but no significant phase width was observed experimentally in the substituted derivative Ca3Mn0.21Ag2.79Ge3.},
  author       = {Ponou, Simeon},
  issn         = {1099-0682},
  keyword      = {superstructure,TiNiSi-type,Zintl phases,Solid-state structures,Intermetallic phases},
  language     = {eng},
  number       = {26},
  pages        = {4139--4147},
  publisher    = {John Wiley & Sons},
  series       = {European Journal of Inorganic Chemistry},
  title        = {On a TiNiSi-Type Superstructure: Synthesis, Crystal and Electronic Structures of CaAgGe and Its Mn-Substituted Derivative},
  url          = {http://dx.doi.org/10.1002/ejic.201000439},
  year         = {2010},
}