Cu3Sn - understanding the systematic absences
1Centre for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden.
Summary
A new superspace model explains previously unexplained diffraction patterns in the intermetallic compound Cu3Sn. This model refines composition and can generate related hexagonal close-packed structures.
Area of Science:
- Materials Science
- Crystallography
- Solid-State Chemistry
Background:
- The intermetallic compound Cu3Sn was previously modeled as a superstructure of Cu3Ti.
- Existing models failed to explain non-crystallographic absences in diffraction patterns and prevented composition refinement.
Purpose of the Study:
- To propose an alternative superspace model for Cu3Sn.
- To explain observed non-crystallographic absences in diffraction data.
- To refine the composition of Cu3Sn.
Main Methods:
- Development of an orthorhombic superspace model (Xmcm(0β0)000).
- Analysis of occupational and displacive modulations.
- Single-crystal X-ray diffraction and Energy Dispersive X-ray Spectroscopy (EDXS).
Main Results:
- The proposed superspace model successfully explains non-crystallographic absences.
- Dominating occupational modulation and weaker displacive modulation were identified.
- Composition was refined to Cu3+xSn, consistent with EDXS data.
Conclusions:
- The superspace model provides a satisfactory explanation for Cu3Sn crystallography.
- Variations in the superspace model can generate ternary Cu3Sn alloys and other hexagonal close-packed (h.c.p.) structures.
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