Change search
ReferencesLink to record
Permanent link

Direct link
The Origins of Superstructure Ordering and Incommensurability in Stuffed CoSn-type Phases
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
Show others and affiliations
2008 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 26, 8195-8214 p.Article in journal (Refereed) Published
Abstract [en]

The CoSn structure type contains large interstitial void spaces that frequently host electropositive guest atoms, such as rare earth elements. In this stuffing process, an intriguing ordering occurs between the neighboring void spaces leading to a family of long-period superstructures comprising intergrowths of the ScFe6Ge6 and ScFe6Ga6 structure types. This superstucture ordering culminates in incommensurability in the REFe6Ge6–δGaδ systems with RE = Sc, Tb, and Lu. In this work, we derive a 3 + 1D superspace model encompassing this series of structures and investigate the origins of the structural trends in this family with electronic structure calculations, at both the LDA-DFT and extended Hckel levels. Using our 3 + 1D model, we refine the structures of four new ErFe6Ge6−δGaδ (0 ≤ δ ≤ 6) phases, two commensurate and two incommensurate, from powder X-ray diffraction data. The refinement results confirm trends observed in the Sc-, Tb-, and Lu-based series: a gradual lengthening and, eventually, turning of the q-vector as Ge is progressively exchanged for Ga. These trends, and the incommensurate ordering as a whole, are traced to a tension between two modes by which the host lattice responds to stuffing atom insertion: (1) an atomic charge modulation enhancing the anionic character of the cavity walls around the guest atoms, and (2) a positional modulation expanding the cavities occupied by guest atoms. These two modes direct the stuffing atom ordering pattern toward opposite ends of the ScFe6Ge6−ScFe6Ga6 intergrowth series. The full series of structures, complex and incommensurate, reflects various degrees of balance between these two factors.

Place, publisher, year, edition, pages
American Chemical Society , 2008. Vol. 130, no 26, 8195-8214 p.
National Category
Chemical Sciences
URN: urn:nbn:se:su:diva-24576DOI: 10.1021/ja077380+ISI: 000257152800035OAI: diva2:197824
Part of urn:nbn:se:su:diva-7194Available from: 2007-11-26 Created: 2007-11-26 Last updated: 2010-09-14Bibliographically approved
In thesis
1. Non-Standard Crystallography: Examples in 3- and 3+1 Dimensional Space
Open this publication in new window or tab >>Non-Standard Crystallography: Examples in 3- and 3+1 Dimensional Space
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Crystallography today is by many seen as merely a tool for determining the structure of a material on the atomic level. It is expected that whatever comes out of the tool is the indisputable truth, a fact. This thesis is based on five publications illustrating that this is very far from the real world of materials research. The experiences drawn from the structural work in the papers are put together to illustrate when to be alert, and how to proceed with a structural investigation using non-standard crystallography. The focus is on interpreting the signs of additional order being present in a structure. The signs may be weak, such as extreme thermal vibration, or unit cell deformation. Or the signs can be strong, with superstructure reflections indicating the presence of either commensurate or incommensurate superstructures.

Place, publisher, year, edition, pages
Stockholm: Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2007. 83 p.
Modulation, Crystallography, intermetallic, materials
National Category
Chemical Sciences
Research subject
Structural Chemistry
urn:nbn:se:su:diva-7194 (URN)978-91-7155-524-3 (ISBN)
Public defence
2007-12-17, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00
Available from: 2007-11-26 Created: 2007-11-26Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Lidin, Sven
By organisation
Inorganic and Structural ChemistryDepartment of Physical, Inorganic and Structural Chemistry
In the same journal
Journal of the American Chemical Society
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 51 hits
ReferencesLink to record
Permanent link

Direct link