Self-Assembly of Two Unit Cells into a Nanodomain Structure Containing Five-Fold Symmetry

Area of Science:

• Materials Science
• Crystallography
• Condensed Matter Physics

Background:

• Periodic crystals traditionally forbid five-fold symmetry.
• The discovery of quasicrystals challenged this notion.
• A structural gap exists between crystalline and quasicrystalline matter.

Purpose of the Study:

• To report a novel nanophase material exhibiting five-fold symmetry.
• To characterize the unique atomic structure of these nanodomains.
• To explore the existence of matter between crystals and quasicrystals.

Main Methods:

• Precipitation of nanophase in Mg-6Zn alloy during isothermal aging at 200 °C.
• Analysis of atomic arrangement in the 2D plane perpendicular to the five-fold axis.
• Investigation of periodic atom arrangement along the five-fold axis.

Main Results:

• Discovery of rod-shaped nanophase with five-fold symmetry, distinct from known crystals and quasicrystals.
• Identification of two separate unit cells (72° rhombus and 72° equilateral hexagon structures) in the 2D plane.
• Observation of periodic atomic arrangement along the five-fold axis.
• Self-assembly of unit cells into nanodomains exhibiting 2D five-fold, C14, and C15 structures.

Conclusions:

• Confirmation of solid matter with structures intermediate to crystals and quasicrystals.
• The findings provide a new model for understanding atomic arrangements in condensed matter.
• Potential to advance the study of self-assembly and metastable phases.