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High Pressure Single Crystal Diffraction at PX^2
Published on: January 16, 2017
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In situ structural analysis of calcium aluminosilicate glasses under high pressure
R F Muniz1, D de Ligny, C Martinet
1Institut Lumière Matière, UMR 5306 CNRS-Université Lyon 1, Université de Lyon, Villeurbanne, France. Departamento de Física, Universidade Estadual de Maringá, Maringá-PR, 87020-900, Brazil.
Summary
High pressure alters calcium aluminosilicate glasses, changing their structure. Si-rich glasses transform their silicon-oxygen networks, while Al-rich glasses show aluminum coordination changes, with permanent effects observed post-compression.
Area of Science:
- Geochemistry
- Materials Science
- Solid State Chemistry
Background:
- Calcium aluminosilicate glasses are crucial in geological and industrial applications.
- Understanding their behavior under pressure is key to predicting geological processes and designing materials.
- Previous studies have explored pressure effects, but the specific role of SiO2 concentration in OH(-)-free systems requires further investigation.
Purpose of the Study:
- To investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses under high pressure.
- To evaluate the influence of SiO2 concentration on glass structure under compression.
- To understand the coordination changes of aluminum and silicon species within the glass network.
Main Methods:
- In situ micro-Raman spectroscopy was employed to monitor structural changes.
- Experiments were conducted at room temperature and varying high-pressure conditions.
- Analysis focused on the T-O-T bridging oxygen bands and the speciation of Q(n) units.
Main Results:
- High pressure led to a decrease in the intensity of the bridging oxygen band, indicating bond alteration or destruction.
- Si-rich glasses exhibited a transformation of Q(n) species to Q(n-1) upon compression.
- Al-rich glasses showed a shift of aluminum from tetrahedral to higher coordination states ([5]Al and [6]Al).
Conclusions:
- Compression significantly alters the structure of calcium aluminosilicate glasses.
- The degree and type of structural change are dependent on the SiO2 concentration.
- Permanent structural modifications, including an increase in three-membered rings in Si-rich samples, were observed after high-pressure recovery.
