Low-temperature evolution of OH bands in synthetic forsterite, implication for the nature of H defects at high pressure
- Ingrin, J
- Liu, J
- Depecker, C
- Kohn, S. C
- Balan, E
- Grant, K. J
DOIAbstract
We performed in situ infrared spectroscopic measurements of OH bands in a forsterite single crystal between -194 and 200 °C. The crystal was synthesized at 2 GPa from a cooling experiment performed between 1,400 and 1,275 °C at a rate of 1 °C per hour under high silica-activity conditions. Twenty-four individual bands were identified at low temperature. Three different groups can be distinguished: (1) Most of the OH bands between 3,300 and 3,650 cm-1 display a small frequency lowering (<4 cm⁻¹) and a moderate broadening (<10 cm⁻¹) as temperature is increased from -194 to 200 °C. The behaviour of these bands is compatible with weakly H-bonded OH groups associated with hydrogen substitution into silicon tetrahedra; (2) In the same frequency r...
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