If, in this season of bonfires and fireworks, you find yourself holding a sparkler, you might like to consider the remarkable chemical reaction that is taking place before your eyes. You are actually witnessing a self-propagating high-temperature synthesis reaction – one in which the energy generated by the reaction of magnesium and oxygen to form magnesium oxide is enough to overwhelm the usual reluctance of the reactants to burn. The process leads to a chain reaction that sees a “solid flame” make its way down the length of the sparkler.

Self-propagating high-temperature synthesis (SHS) reactions like this are rather special. They are very fast and very hot – temperatures in excess of 1000 °C are routinely achieved at the reaction wavefront – and can be used to make a wide range of ceramics.

But there is a twist on the process. In the November issue of Physics World, Quentin Pankhurst and Ivan Parkin describe the discovery by their group at University College London that applying an external magnetic field during the reaction can dramatically alter the structure, microstructure and properties of both the intermediate and the final products.

The global market for ferrites is huge, and intense effort has gone into controlling their magnetic properties, almost always by introducing different atoms into the crystal structures. By providing another method of tailoring the microstructure and magnetic properties, their group are opening the way to a myriad of new materials that could be specially tuned for particular applications.