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Researchers claim solid-state cooling advance

UK: Researchers are said to have produced a device with a large electrocaloric effects which could be used in refrigerators and air conditioners, without needing bulky and expensive magnets.

The device produced by a team at the University of Cambridge is based on layers of a material composed of oxygen and three metallic elements – lead, scandium and tantalum – known as PST.  It is said to display the largest electrocaloric effects (changes in temperature when an electric field is applied) yet observed in a body large enough for cooling applications.

Researchers have been trying to improve traditional cooling technology by replacing refrigerant gases with solid magnetic materials, such as gadolinium. However, according to the Cambridge University team, the performance of prototype devices has been limited to date, as the thermal changes are driven by limited magnetic fields from permanent magnets.

In research published earlier this year, the same Cambridge-led team identified an inexpensive, widely available solid that might compete with conventional coolants when put under pressure. However, developing this material for cooling applications will involve a lot of new design work.

In the current work, the thermal changes are instead driven by voltage. “Using voltage instead of pressure to drive cooling is simpler from an engineering standpoint, and allows existing design principles to be repurposed without the need for magnets,” said Dr Xavier Moya from Cambridge’s Department of Materials Science & Metallurgy.

The Cambridge researchers, working with colleagues in Costa Rica and Japan, used high-quality layers of PST with metallic electrodes sandwiched in between. This is said to have enabled the PST to withstand much larger voltages, and produce much better cooling over a much larger range of temperatures.

“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.

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