Quasi-One-Dimensional Metallicity in Compressed CsSnI₃.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Low-dimensional metal halides possess inherent structural and electronic anisotropies.
• These properties make them promising for exploring novel electronic behaviors.
• Understanding pressure effects is crucial for tuning material properties.

Purpose of the Study:

• To investigate the pressure-induced electronic phase transition in δ-CsSnI3.
• To elucidate the structural and electronic mechanisms behind metallicity.
• To explore high-pressure synthesis of novel electronic materials.

Main Methods:

• High-pressure experiments up to 40 GPa.
• Synchrotron X-ray diffraction and Raman spectroscopy.
• First-principles density functional theory calculations.

Main Results:

• δ-CsSnI3 transitions from an insulator to a metal under pressure.
• The quasi-one-dimensional chain structure of edge-sharing Sn-I octahedra is preserved.
• Pressure induces Sn-Sn hybridization and enhances Sn-I coupling, closing the band gap.
• Interchain interactions remain weak, leading to quasi-1D electronic anisotropy.

Conclusions:

• Pressure effectively induces quasi-1D metallicity in δ-CsSnI3.
• The observed metallicity arises from structural distortions and enhanced intra-chain bonding.
• This work provides a high-pressure route to engineer electronic properties in metal halides.