Jelly work set for materials advance

Sol-gel technology could help in the development of high-tech parts with special properties

Nineteenth century pottery and the US space programme may not appear to have much in common, but they share an interest in a technology which, in its crudest form, is not unlike edible jelly.

Those rubbery cubes are composed of a liquid trapped by solids. And that, according to Dr Carole Harrison, a senior lecturer in inorganic chemistry at Nottingham Trent University, is common to all jelly forms.

Harrison is researching jelly technology – or sol-gel – because of growing interest in the potential for new or improved industrial and scientific materials.

Since 1800, the pottery industry has used gels to make glazes. There was a resurgence of interest at the start of the US space programme, with the search for new super materials. But defence spending cutbacks are forcing people to look at cheaper and better ways of making things.

The sol-gel process can be used to make almost any material, including glass and ceramics of a very high purity. It can also be used to make powders, films and flexible coatings with special properties, as well as opto-electronic components including memory devices, sensors and membranes.

Harrison is looking at the possibility of using sol-gel chemistry to make `interesting’ electrical conductors where the inherently small particles perform reactions. She is also investigating ceramic materials that behave like sponges to soak up other chemicals, perhaps for biological sensing or sniffing applications.

Being a low-temperature process, sol-gel scores over competing methods such as chemical vapour deposition and vacuum sputtering because of the higher purity levels and homogeneity that are possible. It is potentially less complex and less hazardous environmentally. But, because there is much still to learn about sol-gel chemistry, it is expensive.

The process involves removing the water from the jelly. `You tailor the properties of your material by controlling how you get rid of the liquid phase and end up with the solid,’ says Harrison.

A tutorial on sol-gel technology takes place on 22 April at Sira, Chiselhurst, Kent.