High pressure structural and lattice dynamics study of α-In2Se3

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Layered indium selenide (In2Se3) exhibits unique electronic and optical properties.
• Understanding its structural behavior under extreme conditions is crucial for potential applications.

Purpose of the Study:

• To investigate the structural phase transitions of layered α-In2Se3 under high pressure.
• To determine the stability ranges of different In2Se3 phases up to 60+ GPa.

Main Methods:

• In situ synchrotron angle-dispersive powder X-ray diffraction (XRD).
• Raman spectroscopy.
• Diamond anvil cell (DAC) for high-pressure generation.
• Helium as a hydrostatic pressure-transmitting medium.

Main Results:

• A pressure-induced phase transition from α-In2Se3 to monoclinic β'-In2Se3 at approximately 1 GPa.
• The β'-In2Se3 phase is stable up to 45 GPa, with no evidence of transition to the previously reported β-In2Se3 phase.
• Above 45 GPa, In2Se3 transforms into a disordered solid-solution-like orthorhombic structure (phase IV).

Conclusions:

• The high-pressure structural evolution of In2Se3 is more complex than previously understood.
• The discovery of the stable β'-In2Se3 phase and the novel orthorhombic phase IV provides new insights into the pressure-dependent behavior of layered chalcogenides.