Electronic solid could improve eco profile of cooling

Cooling systems, whether in food storage or air conditioning, are generally driven by compressing gases into a liquid state and allowing them to expand, which draws heat in from the environment. This has been a cause of environmental concern for decades: for many years, the working fluids were the cause of atmospheric ozone depletion, and the replacement of these fluids has tended to be low-mass alkanes such as butane and propane, which are flammable and powerful greenhouse gases. A team led by material scientist Xavier Moya of Cambridge University has been working on a replacement for such systems which works by passing an electric current through oxide multilayer capacitors.

In a paper in Nature, Moya and his colleagues describe how they built capacitors consisting of layers of oxides of lead, scandium and tantalum, and explain how these undergo a phase transition when exposed to electric field which draws in heat from the surroundings and causes the largest temperature drop yet observed in a body large enough for cooling applications. This represents an improvement on similar systems that had been investigated containing gadolinium which depends on magnetic fields to induce the phase transition – unlike these, the new material does not need bulky and expensive permanent magnets. “Replacing the heart of prototype magnetic fridges with a material that performs better, and does not require permanent magnets, could represent a game-changer for those currently trying to improve cooling technology,” said co-author Professor Neil Mathur, also of Cambridge.