Crystals for efficient refrigeration

November 05, 2012

Washington, D.C.--Researchers at the Carnegie Institution have discovered a new efficient way to pump heat using crystals. The crystals can pump or extract heat, even on the nanoscale, so they could be used on computer chips to prevent overheating or even meltdown, which is currently a major limit to higher computer speeds. The research is published in the Physical Review Letters.

Ronald Cohen, staff scientist at Carnegie's Geophysical Laboratory and Maimon Rose, originally a high school intern now at the University of Chicago carried out the research. They performed simulations on ferroelectric crystals--materials that have electrical polarization in the absence of an electric field. The electrical polarization can be reversed by applying an external electrical field. The scientists found that the introduction of an electric field causes a giant temperature change in the material, dubbed the electrocaloric effect, far above a temperature to a so-called paraelectric state.

"The electrocaloric effect pumps heat through changing temperature by way of an applied electric field," explained Cohen. "The effect has been known since the 1930s, but has not been exploited because people were using materials with high transition temperatures. We found that the effect is larger if the ambient temperature is well above the transition temperature, so low transition temperature materials are preferred."

Ferroelectrics become paraelectric--that is, have no polarization under zero electric field above their transition temperature, which is the temperature at which a material changes its state from ferroelectric to paraelectric.

Rose and Cohen used atomic-scale molecular dynamics simulations, where they followed the behavior of atoms in the ferroelectric lithium niobate as functions of temperature and an electrical field. Maimon Rose started this work as a high school summer intern and is now in his second year as an undergraduate in biology at the University of Chicago. He worked on the project during breaks as an intern supported by EFree, DOE Energy Frontier Research Center at the Geophysical Laboratory. Rose remarked, "Lithium niobate had not been studied before like this. We were pretty surprised to see such a huge temperature change."
-end-
*The work was supported by the Center for Energy Frontier Research in Extreme Environments (EFree) at the Carnegie Institution's Geophysical Laboratory.

The Carnegie Institution (www.Carnegiescience.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary sciences.

Carnegie Institution for Science

Related Ferroelectric Articles from Brightsurf:

Germanium telluride's hidden properties at the nanoscale revealed
Germanium Telluride is an interesting candidate material for spintronic devices.

Discovery of large family of two-dimensional ferroelectric metals
Recently, a team from University of Chinese Academy of Sciences, led by Prof.

Understanding of relaxor ferroelectric properties could lead to many advances
A new fundamental understanding of polymeric relaxor ferroelectric behavior could lead to advances in flexible electronics, actuators and transducers, energy storage, piezoelectric sensors and electrocaloric cooling, according to a team of researchers at Penn State and North Carolina State.

Pushing periodic disorder induced phase-matching into deep-ultraviolet spectral region
Phase matching condition is the key criteria for the efficient nonlinear frequency conversion.

Controllable functional ferroelectric domain walls under piezoresponse microscope
Although ferroelectric bulk materials have excellent photoelectric, piezoelectric and dielectric properties, they could hardly meet the increasing need for integrated, micro-sized and wearable devices.

Physicists find evidence of previously unseen transition in ferroelectrics
Proposed a century ago, inverse transitions seem to contradict the fundamental law that disorder increases with temperature.

Designer-defect clamping of ferroelectric domain walls for more-stable nanoelectronics
Engineered defects in ferroelectric materials provides key to improved polarisation stability, a significant step forward for domain-wall nanoelectronics in data storage.

Transparency discovered in crystals with ultrahigh piezoelectricity
Use of an AC rather than a DC electric field can improve the piezoelectric response of a crystal.

MIPT researchers close in on new nonvolatile memory
Researchers from MIPT, along with their colleagues from Germany and the U.S., have achieved a breakthrough on the way to new types of nonvolatile memory devices.

Reorganizing a computer chip: Transistors can now both process and store information
Researchers have created a more feasible way to combine transistors and memory on a chip, potentially bringing faster computing.

Read More: Ferroelectric News and Ferroelectric Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.