In situ structural analysis of calcium aluminosilicate glasses under high pressure.
In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al  +  Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ([Formula: see text][T-O-T], where T  =  Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q (n) species to Q (n-1). In the case of Al-rich glass, the Al in the smallest Q (n) units evolved from tetrahedral to higher-coordinated Al (([5])Al and ([6])Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network.
Institut 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.
R F
RF
Muniz
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D
de Ligny
C
C
Martinet
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M
Sandrini
A N
AN
Medina
J H
JH
Rohling
M L
ML
Baesso
S M
SM
Lima
L H C
LH
Andrade
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Y
Guyot