Functional Materials Group

Research into the Physics of Liquids and Solids
on the Nano- to Meso-Scale

Dr. J.B.W. Webber.

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Nano-science :

We study the structure, dynamics and phases of nano-structured to micro-structured liquids and their solids.

Nano-scale to micro-scale volumetric metrology :

The techniques we are developing for nano-scale metrology are based on both physical thermodynamics (Gibbs equations) and on neutron and X-ray scattering.

Nano-science :

The properties of matter change considerably when the matter is structured on the nano-scale to meso-scale. In confined geometry the Gibbs Free Energy is greatly modified, resulting in changes to parameters such as diffusion, transport and the temperature at which phase changes take place.

We have now been studying the structure, dynamics and phases of nano-structured to micro-structured liquids and their solids for more than 20 years, and are actively unraveling the behaviour of liquids in confined geometry, and at and near surfaces. Even so there is much that we still need to understand about even such basic systems as water in a silica pore.

Some of this basic research has been carried out at the University of Kent, some of the more recent work in conjunction with Heriot Watt University. Lab-Tools are continuing these investigations in conjunction with both universities, both in the Lab-Tools NMR laboratory and at central neutron scattering facilities. This research is of great interest in its own right, but also as needed to support the metrology development. Dr. Beau Webber has also been awarded a total of 88 days of neutron scattering time to aid these studies (23 days as main proposer), at the central facilities at the Institute Laue Langevin in Grenoble (ILL); Laboratoire Leon Brillouin (LLB), Saclay, Paris; at the Jülich Centre for Neutron Science (JCNS), Germany, and ISIS at the Rutherford Lab., to investigate this nano-science and nano-metrology.

Our main experimental techniques are based on:
  • NMR relaxation,
  • NMR Cryoporometry (NMRC), (figure 2, 3),
  • NMR diffusion in a magnetic gradient (Static or Pulsed),
  • Neutron Diffraction (NS),
  • Neutron Diffraction Cryoporometry (NDC), (figure 4),
  • Small Angle Neutron Scattering (SANS),
  • Quaasi-Elastic Neutron Scattering (QENS),
  • X-Ray Diffraction (XRD),
  • N2 Gas Adsorption,
  • Differential Scanning Calorimetry (DSC) and
  • Thermoporosimetry.
Our analytic and simulation techniques include:
  • Direct analytic/numerical calulation of small angle neutron scattering from model porous systems, and their alignment to measured scattering results.
  • ab-initio Quantum Mechanical - Molecular Dynamic simulation of liquids at and near surfaces, in model porous systems. (figure 1)
NMR Cryoporometry is a technique for measuring pore size distributions that we originated at Kent and that I have extensively developed.

3D Model of laminar silicon, with surface films of liquid nitrogen - one timestep from a CASTEP ab-initio QM MD simulation.
Figure 1: 3D model of laminar silicon porous system, with surface films of liquid nitrogen - one timestep from a CASTEP ab-initio QM MD simulation.

An example melting point curve, for water ice melting in nominal 100 Angstrom pore diameter Sol-Gel Silica.
Figure 2: An example melting point curve, for water ice melting in nominal 100 Angstrom pore diameter Sol-Gel Silica.
Normalised pore size distributions for selected porous silicas, by NMR Cryoporometry. The intrinsic resolution of the technique is better than the red curve, for SBA-15, which is fully resolved.
Figure 3: Normalised pore size distributions for selected porous silicas, as measured by NMR Cryoporometry. The intrinsic resolution of the technique is better than the red curve, for SBA-15, which is fully resolved. We have now extended the range of the technique from about 1nm to nearly 10µm.
Neutron Diffraction Cryoporometry (NDC).

Figure 4: Neutron Diffraction Cryoporometry (NDC) - a technique which I originated for studying phases as a function of temperature.

Nano-structured liquids

When in pores, water can remain a stable liquid (i.e. in an equilibrium state) more than 20C° below its usual melting temperature - for other liquids the effect can be even larger. Even when ice is formed under these conditions, it can become much more mobile than normal brittle ice, particularly near surfaces.

See our invited paper : Structural and Dynamic Studies of Water in Mesoporous Silicas using Neutron Scattering and Nuclear Magnetic Resonance. Beau Webber and John Dore. Invited article, IoP: Journal of Physics: Condensed Matter - Special Issue: Water in Confined Geometry - 16, S5449-S5470, 2004. PII: S0953-8984(04)78970-5

We now partly understand this behaviour in these confined systems, at least on the larger length scales, in terms of the changes in the thermodynamic state - in particular, alterations of the local Gibbs Free Energy. However there are still less-well understood effects, such as the effect of pore geometry on the thermodynamic state. As one approaches the atomic scale there is a need to use tools that take into consideration the atomic nature of the system. We are now beginning to apply ab-initio quantum mechanical molecular dynamic calculations to throw more light on the behaviour of liquids and their solids near surfaces (see figure 1).

Water/ice systems at interfaces

It is our current belief, from measuring the nano-scale dynamics using NMR relaxation, and the structure from neutron scattering, that there is a layer up to about 1nm thick at ice interfaces where there is considerably enhanced rotational motion, resulting in the continual making and breaking of hydrogen bonds - "plastic ice". This layer also appears to be present at air interfaces, and this may be the reason why glaciers flow - the nano-scale view of the need for plastic terms in the macroscopic viscous-plastic (VP) or elastic-viscous-plastic (EVP) dynamical models of ice and snow-packs in the environment - ( see : Hunke, E. C., Dukowicz, J. K., 1997. An elastic-viscous-plastic model for sea ice dynamics. - Link)

Dr. Beau Webber was recently awarded measurement time on the nuetron quasi-elastic scattering spectrometer IRIS at ISIS, to further investigate the dynamics of these thin surface layers.

See some of our papers :
Plastic ice in confined geometry: The evidence from neutron diffraction and NMR relaxation. J. Beau W. Webber, John C Dore, John H. Strange, Ross Anderson, Bahman Tohidi. J. Phys.: Condens. Matter 19, 415117, 2007, Special Issue: Proceedings of The International Workshop On Current Challenges in Liquid and Glass Science (The Cosener's House, Abingdon, Uk, 10-12 January 2007).

Dynamics at Surfaces : Probing the dynamics of polar and a-polar liquids at silica and vapour surfaces. J. Beau W. Webber, John H. Strange, Philip A. Bland, Ross Anderson and Bahman Tohidi. American Institute of Physics (AIP) Conference Proceedings Series, 1081, 51, 2008. MAGNETIC RESONANCE IN POROUS MEDIA: Proceedings of the 9th International Bologna Conference on Magnetic Resonance in Porous Media (MRPM9). DOI: 10.1063/1.3058545

See my invited review paper :
Studies of nano-structured liquids in confined geometry and at surfaces. J. Beau W.Webber. Progress in NMR Spectroscopy, 56, 1, 78-93, 2010. DOI: 10.1016/j.pnmrs.2009.09.001


Theses studies are relevant to the following :
  • Understanding the properties of water/ice at hydrophilic/hydrophobic and biological interfaces.
  • Understanding how to increase recovery from oil and gas reservoirs,
  • Determining the properties of methane hydrate in model and real marine porous systems,
  • Informing research on porous catalyst support systems,
  • Studying properties that affect the frost resistance of cement and fired clay,
  • Informing high performance nano-structured battery research,
  • Helping predict the longevity of biochar for carbon sequestration.

Ice Flow in Glaciers and Ice Packs

A significant conclusion from both the NMR relaxation studies and the neutron diffraction cryoporometric studies is that plastic ice forms at ice-vapour interfaces, converting to hexagonal ice at low temperatures.
It is well known from the study of the bulk mechanics of sea ice, snow-packs and glaciers, formed predominantly from hexagonal ice, that modeling must be done with either a viscous-plastic (VP) or an elastic-viscous-plastic (EVP) model [3]; this deduction that the ice may be in a state of enhanced rotational motion at each of the myriad of ice-vapour interfaces in compressed snow-packs, leading to a continual breaking and forming of the hydrogen bonds, may be relevant to these studies of ice and snow-packs in the environment. DOI: 10.1063/1.3058545 , DOI: 10.1016/j.pnmrs.2009.09.001

Gas Hydrates confined in Marine Sediments

EPSRC funded work has already indicated that for methane hydrate formed in the pore space of model systems, there is a hysteresis in the phase plots.
The environmental impact of this difference between hydrate formation and dissociation temperatures is that, for a marine hydrate, a small rise in sea temperature (say, 0.1 K), which causes the dissociation of some hydrate and the release of some methane gas, may not be reversible by an equivalent drop in sea temperature but instead require a far greater temperature decrease before the hydrate can re-form. EPSRC Report

Nano-scale to micro-scale metrology :

There are numerous techniques for studing the metrology of surfaces. We are developing the application of physical thermodynamics and neutron and X-ray scattering techniques as tools for studying the metrology throughout the volume of a sample, on the nano-scale through meso-scale to micro-scale dimensions.

We have completed many academic research projects and also industrial and commercial analysis projects for high-profile companies using the techniques that we have developed.

Following the above basic research into the behaviour of liquids and their solids in confined geometry, in well characterised porous materials, we then apply this by imbibing these liquids into as yet uncharacterised porous systems, and use the knowledge that we have gained about the changes in their physical properties, when nano-structured, to deduce information about the host porous structure and metrology.
More information on Lab-Tools Ltd. contract nano- to micro-metrology may be found on our nano-metrology page :

The basic techniques that use these changes in the thermodynamic properties in nano-structured systems are :
  • Gas adsorption,
  • Thermoporosimetry,
  • NMR Cryoporometry.
Of these techniques, NMR Cryoporometry is now often our preferred technique, although the others may provide invaluable comparative information. We have used NMR Cryoporometry in a number of academic research projects and industrial contracts, to measure pore volumes and pore size distributions in materials such as porous carbons, fired and un-fired clays, marine sediments, oil-bearing rocks, meteorite fragments ....
More detailed information about NMR Cryoporometry is available by following the link below to our NMR Cryoporometry pages.

Lab-Tools performs contract analyses of Pore Size Distributions using NMR Cryoporometry :

Lab-Tools has measured pore sizes in a wide range of materials, and the technique can be applied to oil and/or water wet materials, and also to materials that can not be dried out without losing their structure.

The Lab-Tools pore-size distribution measurement range extends from about 1nm to nearly 10µm. Please contact us ( Dr. Beau Webber ) to discuss pore size measurements on your samples. Prices are competitive, but depend on the number of decades of pore-size range to be covered, and precision needed, as these determine the duration of the measurement meeded, which can range from 2 hours to 36 hours.
We frequently find these techniques may be preferable to more established methods such as BET gas adsorption or DSC thermal porisimetry.

X-ray and neutron scattering based metrology calibration program :

With all these thermodynamic techniques, however there is increasingly a supposition that as atomic dimensions are approached, the calibration from the thermodynamics may change.

Thus we have mounted a separate metrology program using neutron and X-ray scattering. These have the advantage that they are inverse techniques, by which is meant that the smaller the structure being observed, the larger is the scattering angle.

Further, there is no existing reason to suppose that these scattering techniques are length-scale dependent. i.e. if one has a good calibration at one length-scale, it should also be good at all other length-scales.

To transform a measured scattering to a metric of the structures in the sample, we create extended models of pore systems, and calculate the scattering using numerical integration. These show very good agreement with measured scattering, figure 3.

Our existing measurements using sol-gel silicas have shown that while the thermodynamic techniques are in close agreement with the scattering measurements for dimensions above 10nm, below this dimension there appears to be an increasing divergence between the scales of the thermodynamic and scattering metrologies.

Dr. Beau Webber has been awarded measurement time at the Institute Laue Langevin (ILL), on the D4 and D22 instruments, and this has enabled him to develop and verify his models. Dr. Beau Webber was recently awarded measurement time (as first user) on the excellent new wide-scattering range ISIS Target Station 2 instrument NIMROD, and 17 porous samples were measured on this most successful run, with very pleasing preliminary results. Simulation models are being run to match the results, and the models, results and conclusions will be presented in a paper.

Fully density corrected radial distribution function measured for 7 sol-gel silicas, compared with that calculated for extended arrays of pores with Gaussian variance.
Figure 3: Fully density corrected radial distribution function measured for 7 sol-gel silicas (red lines), compared with that calculated for extended arrays of pores with Gaussian variance (green dots).
Cryoporometry pages
Porous Media pages


Some of our publications in the field of porous-media, nano-scale to micro-scale structured matter, and confined liquids :
For more information : E-mail me :, see : my publications , go to my research home page. Also, see my Thesis.

Content, design & creation Dr. Beau Webber 2005.
2005_03_20, 2010-10-31