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Author Spotlight: Standardizing the Development of Amine-Based Silica Composites as CO2 Adsorbents for Direct Air Capture
Published on: September 29, 2023
Pressure-induced silica quartz amorphization studied by iterative stochastic surface walking reaction sampling.
Xiao-Jie Zhang1, Cheng Shang1, Zhi-Pan Liu1
1Collaborative Innovation Center of Chemistry for Energy Material, Key Laboratory of Computational Physical Science (Ministry of Education), Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200433, China. zpliu@fudan.edu.cn.
Discover the kinetics of silica amorphization under pressure. New research reveals competing pathways and high energy barriers, explaining this complex crystal to amorphous transformation. Keywords: silica, amorphization, pressure, kinetics, transformation.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Computational Chemistry
Background:
- Crystal to amorphous transformations are crucial in nature but poorly understood due to slow kinetics and disordered structures.
- The amorphization of silica (SiO2) under pressure is a complex, debated process with non-equilibrium kinetics and varied products.
Purpose of the Study:
- To elucidate the kinetics and mechanisms of silica amorphization under external pressure.
- To map the global potential energy surface and identify lowest energy pathways for α-quartz amorphization.
Main Methods:
- Developed iterative reaction sampling based on stochastic surface walking global optimization.
- Investigated silica (SiO2) amorphization under 15 GPa using first-principles calculations.
Main Results:
- Pressurization to 15 GPa thermodynamically initializes amorphization by bringing the quartz phase energetically closer to the amorphous state.
- Identified multiple kinetically competing pathways to dense phases (MI, stishovite, MII, TI) due to flexible Si coordination (4, 5, 6-fold).
- Observed simultaneous crystal-to-crystal and crystal-to-amorphous transitions mediated by five-fold Si structures, with high energy barriers from Si-O bond breaking.
Conclusions:
- High energy barriers and the reconstructive nature of the phase transitions are the primary kinetic origins of silica amorphization under pressure.
- The study provides the first comprehensive view of the global potential energy surface and pathways for α-quartz amorphization.
