Raman Microprobe Spectra and Vibrational Mode Assignments of Talc

Abstract

The Raman spectra of talc microparticles have been obtained with the Raman microprobe over the frequency range 100 to 3800 cm−1. The vibrational modes are discussed in terms of an idealized unit cell (1-M polymorph) of C2h symmetry. An electrostatic dipole-dipole interaction is used to compare the Raman and infrared active branches. Assignments of the Raman active stretching modes of the silicate sheet are found to support previous infrared assignments. Estimates of intrasheet dipole-dipole interactions are obtained.

Magnesium and calcium silicate hydrates

“…The sample shows a Si\ \O\ \Si bending band at 662 cm −1 and Si\ \O stretching vibration bands at 1005 (Q 3 ) and around 880 cm − 1 (Q 2 tetrahedra) [11]. The positions of these bands are in good agreement with the vibrational modes observed for talc (3677, 1020, 890 and 650-670 cm −1 [14,47]). In case of the high calcium samples (0.3M-0.5C-S-H and 0.4M-0.4C-S-H) a small shoulder on the high wavenumber side of the main band due to Si\ \O stretching indicates that there are small amounts of unreacted silica present in those samples [11].…”

“…The Raman spectrum of the M-S-H sample with Mg/Si 0.8 shows similar bands but at different positions. The bands located at 175 cm − 1 are assigned to Mg\ \O lattice vibrations (following the assignment given in [47,51,52] for phyllosilicates), at 220 cm − 1 (O\ \H\ \O vibrations), 361 cm − 1 (O\ \Si\ \O bending), at 455 cm −1 , at 667 cm −1 (Si\ \O\ \Si symmetrical bending), 882 cm −1 and 3686 cm −1 (OH stretching, high wavenumber region not shown) as discussed in more detail in [11]. The shift to higher wavenumbers of the band due to Si\ \O\ \Si symmetrical bending in the M-S-H sample compared to C-S-H is further indicative for a higher polymerisation degree of the silicate network (see inset of Fig.…”

Structure-Composition Relationships in Trioctahedral Chlorites: A Vibrational Spectroscopy Study

“…This band was assigned to internal movements of octahedral sheets. Such a band has also been found in talc (Blaha and Rosasco, 1978;Rosasco and Blaha, 1980). A weak band at about 280 cm -~ was assigned by Ishii et al (1967) and Shirozu (1985) to tetrahedral movements with the symmetry species E13.…”

Pseudomorphic replacement of diopside during interaction with (Ni,Mg)Cl2 aqueous solutions: Implications for the Ni-enrichment mechanism in talc- and serpentine-type phases

“…Comparison with Ni-and/or Mg-end-member phases from the RRUFF database (Downs, 2006) indicates that the replacement phase is willemseite [ideal composition Ni 3 Si 4 O 10 (OH) 2 ], which is a Ni-end-member composition of talc. Thus, the 192 cm −1 band can be attributed to the stretching vibration of MO 6 octahedron (where M is Ni or Mg) (Loh, 1973) of a talc-type structure, whereas the intense vibrational mode at 675 cm −1 is due to symmetrical stretching vibrations of the Si\O(bridging)\Si bond in SiO 4 tetrahedra (Rosasco and Blaha, 1980). The MO 6 Raman peak of Mg-poor willemseite shows a small shift towards lower wavenumbers relative to that of Ni-rich talc phase.…”