Elsevier

Applied Clay Science

Volume 96, July 2014, Pages 22-35
Applied Clay Science

Review article
Neutron scattering, a powerful tool to study clay minerals

https://doi.org/10.1016/j.clay.2014.05.004Get rights and content

Highlights

  • A variety of water diffusion processes in clays is studied by neutron spectroscopy.

  • Neutron isotopic sensitivity is crucial for structural studies.

  • Molecular dynamics and Monte-Carlo simulations give vital input to clay sciences.

  • Instrumentation and modeling development will bring new insights into clay sciences.

Abstract

Of the techniques used to study clay minerals, neutron scattering has become more familiar to clay scientists over the past decade. A brief account of neutron scattering theory is given in this review, followed by a description of measurements that can be made using neutron diffraction and neutron scattering spectroscopy, and especially quasi-elastic neutron scattering. Then recent examples of the application of neutron scattering methods to the study of clay minerals are presented, and finally the potential advantages of such experimental results when combined to molecular dynamics are discussed. To conclude, the potential perspectives that the European Spallation Source brings to this subject are pointed out.

Introduction

The usefulness of smectites in many industries stems from their ability to take up and retain large amounts of water due largely to their high interlayer surface area and presence of hydrated cations (Bérend et al., 1995, Cases et al., 1992, Cases et al., 1997, Ormerod and Newman, 1983). Neutron scattering spectroscopy has been used to probe water mobility dynamics in clay minerals for more than 4 decades (Adams et al., 1979, Cebula et al., 1981, Hunter et al., 1971, Olejnik and White, 1972, Olejnik et al., 1970, Poinsignon et al., 1987, Ross and Hall, 1978, Tuck et al., 1984, Tuck et al., 1985), but interest in this methodology has increased markedly since the mid 1990s (Bordallo et al., 2008, Chakrabarty et al., 2006, Gates et al., 2012, Kamitakahara and Wada, 2008, Malikova et al., 2006, Michot et al., 2007, Nair et al., 2005, Powell et al., 1997, Powell et al., 1998, Swenson et al., 2000, Swenson et al., 2001a, Williams et al., 1998) in conjunction with developments in molecular dynamic simulations (Skipper et al., 1991, Skipper et al., 1994, Skipper et al., 1995, De Siqueira et al., 1999, Greathouse et al., 2000, Skipper et al., 2000, De Carvalho and Skipper, 2001, Sutton and Sposito, 2001, Marry et al., 2002, Marry and Turq, 2003, Marry et al., 2008, Wang et al., 2004, Wang et al., 2006, Malikova et al., 2006).

Water mobility in smectites is largely controlled by the type of interlayer cation (Bordallo et al., 2008, Cases et al., 1992, Gates et al., 2012). The interactions of water (solutes) with the different surfaces of smectites often have diffusion or exchange times on the order of 10 ps to 100 ms that correspond in part to the time scale probed by neutron spectroscopy. Other methods, such as nuclear magnetic resonance (e.g., Bowers et al., 2011), are also highly successful at probing these interactions, but will not be discussed here.

Neutron scattering has several features that make it a powerful technique to study the structure and dynamics of heterogeneous systems such as smectite–water dynamics. The wavelength of thermal neutrons is suitable for probing the structure of a clay at the molecular level (neutron powder diffraction, NPD), as well as their long range order in colloidal dispersions and the macroscopic structure of the particles themselves (small-angle neutron scattering, SANS) (Cebula and Thomas, 1978). When compared to X-ray diffraction, neutron diffraction offers the advantage of a smaller attenuation coefficient, thus making surface effects negligible. Moreover in the study of sol or gel states the wavelength of the neutrons can be adjusted, so that Bragg diffraction reflections resulting from the clay mineral structure can be avoided. Additionally, by varying the hydrogen-deuterium ratio of the fluid, or possibly even the clay mineral itself, the contrast between the mineral particles and their surrounding water molecules can be better identified. On the other hand, although water dynamics can be investigated by many experimental techniques, such as infrared and Raman spectroscopies (Brubach et al., 2001) and nuclear magnetic resonance (NMR) (Kyakuno et al., 2011), neutron scattering spectroscopy offers a number of advantages presented in this work (Bordallo et al., 2008, Cebula et al., 1979, Cole et al., 2006, Malikova et al., 2008). Due to the exceptionally large scattering cross-section of the H-atoms, incoherent inelastic neutron scattering (IINS) enables probing of diffusive proton motions over a broad time-scale (from few nano to a few hundred ps) as well as the observation of quite high vibrational frequencies (up to 2000 cm 1).

To date, neutron flux has been a key challenge in the study of many interesting problems in clay science, where understanding of kinetic effects is of the foremost importance. The unprecedented neutron flux offered by the European Spallation Source (operational in 2020) will, however, open up new opportunities for enquiry. For example, ESS will enable detailed dynamic analysis of real-time hydration and dehydration processes in clays. In order to better take advantage of this experimental technique, the most important theoretical points that must be known by novices, as well as examples of successful experiments, are described in this review.

Section snippets

Neutron scattering: an overview

Neutrons are non-charged subatomic particles, first postulated by Rutherford in 1920 and later observed by J. Chadwick in 1932. They are found in all atomic nuclei with exception of the hydrogen atom (1H) and have a comparable mass to protons, a magnetic moment of − 1.913 μb and a nuclear spin of 1/2.

Neutron scattering techniques are based on the analysis of momentum and energy transfer, which may occur following interactions between neutrons and matter. Note that during such interaction the

Smectite swelling at ambient conditions

As already mentioned (Table 1), neutron scattering lengths are isotope-dependent. For instance, neutron scattering lengths for H, D, Si, and Al are − 3.74, 6.67, 4.15, and 3.45 fm, respectively. As a consequence, structural studies of water in clay minerals are possible and largely benefit from the isotopic dependence on scattering length. Using H2O/D2O exchange yields additional information that is helpful on getting the precise location of hydrated species. The use of neutron diffraction to

Quasi-elastic neutron scattering (QENS) of clay minerals

The first studies of smectites by means of QENS date back to 1970 (Hunter et al., 1971, Olejnik and White, 1972, Olejnik et al., 1970) and since then, it has been possible to achieve remarkable results regarding the water dynamics and the variety of diffusion processes in these materials (Bordallo et al., 2008, Swenson et al., 2000, Nair et al., 2005 Gates et al., 2012, Chakrabarty et al., 2006, Malikova et al., 2006, Michot et al., 2007, Poinsignon et al., 1987, Swenson et al., 2001b).

The QENS

Molecular dynamics and Monte-Carlo simulations: getting the most of experimental data

Molecular simulations (molecular dynamics and Monte Carlo approaches) offer a description of matter at the atomic level, Fig. 9. Therefore they are useful tools to interpret many experiments covering spatial and time scales matched by neutron scattering in clay minerals.

In molecular dynamics simulations (MD), the atoms are considered as classical objects submitted to the Newton's equation of motion, which is propagated step by step thanks to an algorithm (usually Verlet or Velocity Verlet

Final remarks and perspectives

Neutron scattering methods have been applied to problems in the Earth and mineral sciences for many decades and more recently a rebirth of its use has been observed. This current growing interest is partly due to the development of improved neutron sources as well as the development of new methods and instrumentation. With this in mind, and considering that there is a wide range of interesting phenomena of interest to clay scientists that can be studied using neutron scattering, this review

Acknowledgments

MLM research is supported through the Brazilian Science without Borders (Process number 246604/2012-3) program. Some travel support was provided to WPG from the Australian Research Council's Discovery Project Scheme DP130102203. HNB thanks the invaluable discussions with Nikolaos Tspatsaris about many issues regarding how to better present the complex theory of neutron scattering to non-experts. We acknowledge the support of the ISIS Facility, ILL and FRM2 for providing the neutron facilities

References (94)

  • J.W. Wang et al.

    Effects of substrate structure and composition on the structure, dynamics and energetics of water at mineral surfaces: a molecular dynamics modeling study

    Geochim. Cosmochim. Acta

    (2006)
  • J.M. Adams et al.

    The diffusion of interlamellar water in the 23.3 Å Na-montmorillonite-pyridine/H2O intercalate by quasielastic neutron scattering

    Clay Clay Miner.

    (1979)
  • M.A. Anderson et al.

    Properties of water in calcium and hexadecyltrimethylammonium-exchanged bentonite

    Clay Clay Miner.

    (1999)
  • G.E. Bacon

    Neutron Diffraction

    (1975)
  • M. Bée

    Quasielastic Neutron Scattering, Principles and Applications in Solid State Chemistry, Biology and Materials Science

    (1988)
  • I. Bérend et al.

    Mechanism of adsorption and desorption of water vapour by homoionic montmorillonites: 2. The Li+, Na+, K+, Rb+ and the Cs+ exchanged form

    Clay Clay Miner.

    (1995)
  • H.J.C. Berendsen et al.
  • I. Bihannic et al.
  • H.N. Bordallo et al.

    Quasi-elastic neutron scattering studies on clay interlayer-space highlighting the effect of the cation in confined water dynamics

    J. Phys. Chem. C

    (2008)
  • G.M. Bowers et al.

    Alkali metal and H2O dynamics at the smectite/water interface

    J. Phys. Chem. C

    (2011)
  • J.B. Brubach et al.

    Dependence of water dynamics upon confinement size

    J. Phys. Chem. B

    (2001)
  • J.M. Cases et al.

    Mechanism of adsorption and desorption of water vapour by homoionic montmorillonites: 1. The sodium exchanged form

    Langmuir

    (1992)
  • J.M. Cases et al.

    Mechanism of adsorption and desorption of water vapour by homoionic montmorillonite: 3. The Mg2 +, Ca2 +, Sr2 + and Ba2 + exchanged forms

    Clay Clay Miner.

    (1997)
  • D.J. Cebula et al.

    Neutron scattering from colloids

    Faraday Discuss. Chem. Soc.

    (1978)
  • D.J. Cebula et al.

    Neutron diffraction from clay–water systems

    Clay Clay Miner.

    (1979)
  • D.J. Cebula et al.

    Diffusion of water in Li–Montmorillonite studied by quasi-elastic neutron scattering

    Clay Clay Miner.

    (1981)
  • F.C. Chang et al.

    Computer simulation of interlayer molecular structure in sodium montmorillonite hydrates

    Langmuir

    (1995)
  • D.R. Cole et al.
  • G.J. Cuello et al.
  • R.T. Cygan et al.

    Molecular models of hydroxide, oxyhydroxide, and clay phases and the development of a general force field

    J. Phys. Chem. B

    (2004)
  • R. De Carvalho et al.

    Atomistic computer simulation of the clay–fluid interface in colloidal laponite

    J. Chem. Phys.

    (2001)
  • C. De la Calle et al.

    Mode d'Empilement des feuillets dans les vermiculites hydratees a'deux couches

    Clay Miner.

    (1978)
  • A.V. De Siqueira et al.

    The structure of pore fluids in swelling clays at elevated pressures and temperatures

    J. Phys. Condens. Matter

    (1999)
  • European Spallation Source (ESS)
  • E. Ferrage et al.

    New insights on the distribution of interlayer water in bi-hydrated smectite from X-ray diffraction profile modeling of 00l reflections

    Chem. Mater.

    (2005)
  • E. Ferrage et al.

    Hydration properties and interlayer organization of water and ions in synthetic Na-smectite with tetrahedral layer charge. Part 1. Results from X-ray diffraction profile modeling

    J. Phys. Chem. C

    (2010)
  • E. Ferrage et al.

    Hydration properties and interlayer organization of water and ions in synthetic Na-smectite with tetrahedral layer charge. Part 2. Toward a precise coupling between molecular simulations and diffraction data

    J. Phys. Chem. C

    (2011)
  • D. Frenkel et al.

    Understanding Molecular Simulations, From Algorithms to Applications

    (2002)
  • J.J. Fripiat et al.

    Thermodynamic properties of adsorbed water molecules and electrical conduction in montmorillonites and silicas

    J. Phys. Chem.

    (1965)
  • W.P. Gates et al.

    Neutron time-of-flight quantification of water desorption isotherms of montmorillonite

    J. Phys. Chem. C

    (2012)
  • F. Gonzalez-Sanchez et al.

    Translational diffusion of water and its dependence on temperature in charged and uncharged clays: a neutron scattering study

    J. Chem. Phys.

    (2008)
  • J.A. Greathouse et al.

    Molecular dynamics simulation of water mobility in magnesium-smectite hydrates

    J. Am. Chem. Soc.

    (2000)
  • P.L. Hall et al.

    Incoherent neutron scattering function for molecular diffusion in lamellar systems

    Mol. Phys.

    (1978)
  • R.K. Hawkins et al.

    Interfacial water structure in montmorillonite from neutron diffraction experiments

    Clay Clay Miner.

    (1980)
  • M. Holmboe et al.

    Molecular dynamics simulations of water and sodium diffusion in smectite interlayer nanopores as a function of pore size and temperature

    J. Phys. Chem. C

    (2014)
  • F. Hubert et al.

    Investigating the anisotropic features of particle orientation in synthetic swelling clay porous media

    Clay Clay Miner.

    (2013)
  • Cited by (34)

    • Layer charge effects on anisotropy of interlayer water and structural OH dynamics in clay minerals probed by high-resolution neutron spectroscopy

      2021, Applied Clay Science
      Citation Excerpt :

      The non-linear loss of S(Q, |ω| < Δω) intensity with increased T indicated the onset of motions faster than the instrumental resolution (~4.1 × 10−9 s). In other words, thermally local structural fluctuations and D2O motions were out of the instrument resolution in the ns time scales (Qvist et al., 2011; Martins et al., 2014), but contributed to a Q- and T-dependent change in S(Q, |ω| < Δω). Thus, the EFW scans (Figs. 2 and 3) indicate, not unexpectedly, that non-localised D2O motions initialised at higher temperature than corresponding localised OH motions.

    • Prediction of the radionuclide inventory in the European Spallation Source target using FLUKA

      2020, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
      Citation Excerpt :

      The European Spallation Source (ESS) is a large-scale facility that will be used for studies of the structure and dynamics of materials using neutrons [1,2]. Neutron scattering is a well-developed method and is used extensively to investigate the fundamental properties of materials in fields such as physics, chemistry, biology, medicine and geology [3–5]. The ESS facility consists of a linear accelerator that will deliver 2.86 ms proton pulses at a rate of 14 Hz onto a tungsten target, where fast neutrons will be produced via spallation reactions.

    • The pH influence on the intercalation of the bioactive agent ciprofloxacin in fluorohectorite

      2018, Applied Clay Science
      Citation Excerpt :

      Therefore, the results from the EFW experiments (Fig. 7a, Fig. 7b and Fig. 7c) demonstrate that all samples have a dynamical process that falls within the observation time window of MARS, with LiFHt showing the largest MSD at 300 K. Up to 250 K (23 °C) the MSD of LiFHt, at both ambient conditions and after drying, presents the same behavior while above this temperature the former exhibit a second change in the slope. In the case of clay minerals, such slope change is commonly attributed to the presence of bulk-like water that is easily removed on heating at 100 °C (Gates et al., 2012; Martins et al., 2014; Gates et al., 2017). Moreover, after drying LiFHt loses 36% of its MSD at 300 K (Fig. 7a), i.e. 64% of its MSD is conserved.

    • Clay mineral–water interactions

      2018, Developments in Clay Science
    View all citing articles on Scopus
    View full text