Early crystallization of amorphous selenium under high pressure studied by synchrotron XRD method

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Amorphous selenium (a-Se) exhibits complex high-pressure behavior.
• Previous studies reported conflicting crystallization pressures for a-Se under pressure.

Purpose of the Study:

• To investigate the effect of heat treatment on the high-pressure crystallization behavior of amorphous selenium.
• To clarify the discrepancies in previously reported crystallization pressures for a-Se.

Main Methods:

• In-situ high-pressure X-ray diffraction (XRD) measurements were performed on a-Se samples.
• Two sets of experiments were conducted: one with a heat-treated sample and one without.

Main Results:

• Heat-treated a-Se showed partial crystallization at 4.9 GPa and complete crystallization around 9.5 GPa.
• Untreated a-Se crystallized at 12.7 GPa, consistent with prior research.
• Prior heat treatment demonstrably lowers the pressure-induced crystallization point.

Conclusions:

• Heat treatment of a-Se promotes earlier crystallization under high pressure.
• This finding provides a potential explanation for the varied crystallization pressures reported in previous studies.
• Understanding the role of pre-treatment is crucial for characterizing the high-pressure phase transitions of amorphous materials.