• journal_title：American Mineralogist
• Contributor：Stephen A. Parry ; Alison R. Pawley ; Ray L. Jones ; Simon M. Clark
• Publisher：Mineralogical Society of America
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2007.2211
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：92
• issue：4
• firstpage：525
• section：Articles

The effects of pressure on the OH stretching frequencies of natural talc and two samples of synthetic 10-Å phase have been measured using a diamond-anvil cell and a synchrotron infrared source. The 10-Å phase was synthesized at 6.0–6.5 GPa, 600 °C for 46 hours (sample 10Å-46) and 160 hours (10Å-160). Spectra were collected up to 9.0 GPa (talc), 9.9 GPa (10Å-46), and 9.6 GPa (10Å-160). The OH stretching vibration of Mg₃OH groups in talc occurs at 3677 cm⁻¹ at ambient pressure, and increases linearly with pressure at 0.97(2) cm⁻¹ GPa⁻¹. The same vibration occurs in 10-Å phase, but shows negligible pressure shift up to 2 GPa, above which the frequency increases linearly to the maximum pressure studied, at a rate of 0.96(3) cm⁻¹ GPa⁻¹ (10Å-46) and 0.87(3) cm⁻¹ GPa⁻¹ (10Å-160). Two other prominent bands in the 10-Å phase spectrum are suggested to be due to stretching of interlayer H₂O, hydrogen-bonded to the nearest tetrahedral sheet. These bands also show little change over the first 2 GPa of compression, as most of the compression of the structure is taken up by closing non-hydrogen bonded gaps between interlayer H₂O and tetrahedral sheets. Between 2 and 4 GPa, changes in band intensities suggest a rearrangement of the interlayer H₂O.