Synthesis, structure, and properties of BaAl2Si2

Area of Science:

• Solid State Chemistry
• Materials Science
• Crystallography

Background:

• Barium aluminum silicide (BaAl2Si2) is an inorganic compound with potential applications in materials science.
• Understanding its crystal structure and properties is crucial for further research and development.

Purpose of the Study:

• To synthesize and characterize single crystals of BaAl2Si2.
• To determine its crystal structure and investigate its phase transition behavior.
• To explore its electronic and magnetic properties.

Main Methods:

• Single crystal growth from an aluminum molten flux.
• Single-crystal X-ray diffraction at low temperatures (10 and 90 K).
• Single-crystal neutron diffraction at room temperature.

Main Results:

• BaAl2Si2 crystallizes in the alpha-BaCu2S2 structure type (space group Pnma).
• It forms an open 3D framework with aluminum and silicon in a covalent network, encapsulating Ba2+ cations.
• Unit cell dimensions were determined: a=10.070(3) Å, b=4.234(1) Å, c=10.866(3) Å.
• No alpha to beta phase transition was observed, unlike in BaAl2Ge2.
• The compound exhibits metallic electronic resistivity and Pauli paramagnetic behavior.

Conclusions:

• BaAl2Si2 is a stable compound with a unique 3D framework structure.
• Its structural and electronic properties differ from the germanium analog, BaAl2Ge2.
• The findings provide fundamental insights into the Ba-Al-Si system and related materials.