Ordering of water in opals with different microstructures


Eckert J., Gourdon O., Jacob D. E. , MERAL Ç., Monteiro P. J. , Vogel S. C. , ...More

EUROPEAN JOURNAL OF MINERALOGY, vol.27, no.2, pp.203-213, 2015 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 27 Issue: 2
  • Publication Date: 2015
  • Doi Number: 10.1127/ejm/2015/0027-2428
  • Journal Name: EUROPEAN JOURNAL OF MINERALOGY
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.203-213
  • Keywords: opal, water, TEM, inelastic neutron scattering, neutron diffraction, FTIR, NEUTRON-SCATTERING, VIBRATIONAL-SPECTRA, SILANOL GROUPS, ICE, DYNAMICS, CRYSTALLINE, TEMPERATURE, MINERALS, MODELS, SITES

Abstract

Opal has long fascinated scientists. It is one of the few minerals with an amorphous structure, and yet, compared to silica glass, it is highly organized on the mesoscale. By means of inelastic neutron scattering (INS), we could document that in four samples of opal at low temperature an ice-like structure of water is present, with details depending on microstructural characteristics. While FTIR spectra for all samples are nearly identical and thus not very informative, INS shows clear differences, highlighting the significance of microstructures. Neutron diffraction at 100 K on one of the opal samples provides evidence for crystalline cubic ice.