Electrocaloric effect

Electrocaloric effect

The electrocaloric effect is where a material shows a reversible temperature change under an applied electric field.

Electrocaloric materials were the focus of significant scientific interest in the 1960s and 1970s, but were not commercially exploited as the electrocaloric effects were insufficient for practical applications, the highest response being 2.5 degrees Fahrenheit (1.4 degrees Celsius) under an applied field of 750 volts. The underlying mechanisms of the effect were also not fully established, with a number of differing theories being proposed. A quantum-mechanical treatment was only developed in the 1990s.

In March 2006 it was reported in the journal Science that thin films of perovskite PZT showed the strongest electrocalorific response yet reported, with the materials cooling down by up to 12 °F (7 °C) in a field of just 25 volts.

A while ago, the electrocaloric effect was thought to be too weak for use in practical technology. But, because of research and new techniques, it is now chosen as a viable technique for use in computer cooling (2006), and prototypes for such coolers are now being created.

A team from Cambridge has found a ceramic material that has a gigantic electrocaloric effect, 100 times stronger than other known materials, such as perovskite. Their material, a mixture of lead, titanium, oxygen and zirconium, becomes cold with the push of a button, they said to Science magazine. The researchers used a board of 350 nanometers, which they managed to cool 12 °C (22 °F) by means of a potential difference of 25 volts. By combining several such heat pumps, an effective cooling system could be created. Room temperature devices are being worked on, as their device works best at 220 °C (430 °F) ambient temperature.

A team at the Pennsylvania State University has developed a ferroelectric polymer that can achieve 12 °C of cooling (Science 8 August 2008).

The opposite effect is called pyroelectric effect.

External links

cite journal
author = A. S. Mischenko "et al"
year = 2006
month = March
title = Giant Electrocaloric Effect in Thin-Film PbZr0.95Ti0.05O3
journal = Science
volume = 311
issue = 5765
pages = 1270–1271
id =
url = http://www.sciencemag.org/cgi/content/full/311/5765/1270
doi = 10.1126/science.1123811


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