Probing past and future materials with neutrons

Box 1 | Analysing the old and the new

Neutrons can be used to analyse all sorts of materials. Here we describe just a few examples of the use of neutrons to analyse the structure and composition of new materials being developed and old materials dug up from the past.

Lung surfactants

Some premature babies have severe difficulty breathing and suffer from a condition called respiratory distress syndrome. The babies lack a protein that is usually present on the surface of the lung to prevent collapse of the air sacs and keep the lungs inflated.

Researchers at the University of Queensland have used neutrons to study the protein structure and its interaction with other molecules in the liquid at the surface of the lung. They found that the protein changes shape as it is compressed during breathing and hope that this information will lead to therapies to treat the condition.

Geopolymer concrete

Experiments at extremely high pressures and temperatures using neutrons are being done to find out how the composition of geopolymers changes their molecular structure and their physical characteristics. Geopolymers have possible uses as:

  • geopolymer concrete to replace Portland cement;
  • light weight composites that can tolerate high temperatures;
  • materials to encapsulate radioactive waste for safe storage; and
  • ceramics that can be cast in moulds.

Negative thermal expansion

Researchers at the University of Sydney are looking at the structure and dynamics of a new family of crystal materials that have the novel ability to contract, rather than expand, when warmed. The new crystals have units of molecules connected by bridges. Neutron scattering has shown that heating changes the molecular vibrations across the bridges, providing a possible explanation for the behaviour.

Microstructure of complex fluids

Many everyday household and personal care products are a complex mix of ingredients. The mixes are liquid-like or semi-solid depending on the temperature. Making products such as fabric conditioners, shampoos and shower gels can be more easily controlled if their structure is understood. The results of investigating the behaviour of the molecules at different temperatures have led to time and energy savings during their manufacture.

Genuine or fake?

Neutron diffraction is a new tool to study priceless archaeological artefacts or museum objects without destroying them. Genuine articles can be distinguished from fakes.

Traditionally, researchers have had to sacrifice some of the object for analysis by obtaining a core sample or grinding a sample to fine powder. Neutrons however can easily penetrate thick surface coatings or layers of corrosion of an intact object: the whole sample can be analysed rather than just a portion of it. Neutron diffraction can provide information about the mineral or metal composition, or orientation of crystals in the material. Deformations in the material or its crystal structure can provide valuable information about the objects history such as how it was made by ancient craftsmen.

Boxes
Box 2. The development of neutron beam science
Box 3. Access for all

Related sites
Lung surfactant 'squeeze out' (Council for the Central Laboratory of the Research Councils, UK)
Welded aerospace components and structures - taking the stress out of flying (Council for the Central Laboratory of the Research Councils, UK)
Flow phenomena in fluids (Council for the Central Laboratory of the Research Councils, UK)
Genuine or fake? Neutron diffraction for non-destructive testing of museum objects (Council for the Central Laboratory of the Research Councils, UK)

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Posted March 2007.