Infrared study of some 7 Å and 14 Å layer silicates by deuteration

抄録

Vibrations involving hydroxyls in the infrared spectra of two synthetic 7 Å trioctahedral minerals (amesite and aluminian lizardite) and of seven natural 14 Å minerals (five trioctahedral chlorites of the Mg–Fe series, sudoite, and cookeite) have been investigated by comparison of the spectra with those of partially deuterated forms obtained by hydrothermal treatments with D₂O. The results are interpreted to indicate that the OH bands between 850 cm⁻¹ and 600 cm⁻¹ in the trioctahedral minerals arise from librations of the outer OH in the 7 Å minerals or the interlayer OH in the 14 Å minerals, expressed by (SiAl)O–OH (∼800 cm⁻¹) and (SiSi)O–OH (∼720 cm⁻¹), and of the inner OH in the 7 Å minerals or the 2 : 1 layer OH in the 14 Å minerals (∼650 cm⁻¹). These librations are correlated with the OH stretching vibrations in a reversed frequency relation. The shoulders around 930 cm⁻¹ in sudoite and cookeite are confirmed to be due to the dioctahedral 2 : 1 OH. Some additional information on the OH stretching bands and on the lattice vibration bands has also been obtained.