Nanoporosity boosts irradiation-induced dynamics in silica

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Hard X-ray irradiation induces structural relaxations in glasses below their glass transition temperature.
• The precise mechanisms of radiation-induced structural rearrangements in glasses are not fully understood.
• The role of porosity and internal surfaces in these processes requires further investigation.

Purpose of the Study:

• To investigate the effect of porosity and internal surfaces on radiation-induced structural and dynamical changes in amorphous silicon dioxide (SiO2).
• To compare the behavior of bulk amorphous SiO2 with nanoporous silica under hard X-ray irradiation.
• To elucidate the influence of nanostructures on the kinetics and dynamics of irradiation-induced relaxations.

Main Methods:

• Comparative study of bulk amorphous SiO2 and nanoporous silica using hard X-ray irradiation.
• Analysis of structural evolution via X-ray diffraction, focusing on the first sharp diffraction peak.
• Characterization of atomic-scale dynamics, including relaxation processes and fluctuations.

Main Results:

• Nanoporous silica exhibits an accelerated reduction in the first sharp diffraction peak intensity under irradiation compared to bulk SiO2.
• Despite faster structural evolution, atomic-scale dynamics in nanoporous silica remain ballistic-like with intermittent fluctuations.
• Both materials display compressed-exponential relaxations at the first sharp diffraction peak, with faster time scales and enhanced fluctuations in nanoporous silica.

Conclusions:

• Internal interfaces in nanoporous silica are critical in controlling hard X-ray-driven relaxation.
• Nanostructuring provides a pathway to tune the radiation sensitivity of glasses.
• The findings offer insights into manipulating radiation effects in nanostructured materials.