Memory effect under pressure in low density amorphous silicon

TL;DR

This study reveals a unique pressure-induced memory effect in low density amorphous silicon, where the amorphous phase reappears upon pressure release and transforms reversibly under higher pressures, supported by first principles calculations.

Contribution

It demonstrates a novel pressure-induced memory effect in amorphous silicon, combining experimental observations with theoretical insights.

Findings

Porous Si undergoes crystalline phase transitions under pressure.

Amorphous phase appears only after pressure release.

Reversible transformation to a higher coordinated phase shows memory effect.

Abstract

Our investigations on porous Si show that on increase of pressure it undergoes crystalline phase transitions instead of pressure induced amorphization - claimed earlier, and the amorphous phase appears only on release of pressure. This amorphous phase, when subjected to higher pressures, transforms reversibly to a higher coordinated primitive hexagonal phase showing a kind of memory effect which may be the only example of its kind in the elemental solids. First principles calculations and thermodynamic arguments help understand these observations.