Issue 32, 2017

Differentiating between long and short range disorder in infra-red spectra: on the meaning of “crystallinity” in silica

Abstract

Local atomic disorder and crystallinity are structural properties that influence greatly the resulting chemical and mechanical properties of inorganic solids, and are used as indicators for different pathways of material formation. Here, these structural properties are assessed in the crystals of quartz based on particle-size-related scattering processes in transmission infra-red spectroscopy. Independent determinations of particle size distributions in the range 2–100 μm of a single crystal of quartz and defective quartz with highly anisotropic micro-crystallites show that particle sizes below the employed wavelength (approx 10 μm) exhibit asymmetric narrowing of absorption peak widths, due to scattering processes that depend on the intra-particle structural defects and long range crystallinity. In particular, we observe that the 1079 cm−1 peak could be used to assess crystallinity, because it shows an asymmetric peak shape shift toward a higher wavelength, depending on the crystallite size. We observe that the 694 cm−1 peak could be used to assess local atomic disorder as it does not show scattering and peak shape changes when absorption effects dominate, below 2 μm. We propose coupling particle size assessments with infra-red peak shape analysis as a method to characterize crystallinity and short range order for studying recrystallization in natural silica, as well as defectivity in many different types of silicas used for industrial and technological applications.

Graphical abstract: Differentiating between long and short range disorder in infra-red spectra: on the meaning of “crystallinity” in silica

Supplementary files

Article information

Article type
Paper
Submitted
22 May 2017
Accepted
19 Jul 2017
First published
19 Jul 2017

Phys. Chem. Chem. Phys., 2017,19, 21783-21790

Differentiating between long and short range disorder in infra-red spectra: on the meaning of “crystallinity” in silica

Y. Asscher, G. Dal Sasso, L. Nodari, I. Angelini, T. Boffa Ballaran and G. Artioli, Phys. Chem. Chem. Phys., 2017, 19, 21783 DOI: 10.1039/C7CP03446F

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