Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bottom-up approach provides first characterization of pyroelectric nanomaterials

09.01.2013
By taking a "bottom-up" approach, researchers at the University of Illinois at Urbana-Champaign have observed for the first time that "size does matter" in regards "pyroelectricity"—the current/voltage developed in response to temperature fluctuations that enables technologies such as infrared sensors, night-vision, and energy conversion units, to name a few.

"Controlling and manipulating heat for applications such as waste heat energy harvesting, integrated cooling technologies, electron emission, and related functions is an exciting field of study today," explained Lane Martin, an assistant professor of materials science and engineering at Illinois. "Traditionally, these systems have relied on bulk materials, but future nanoscale devices will increasingly require ferroelectric thin films.

"Measuring the pyroelectric response of thin films is difficult and has restricted the understanding of the physics of pyroelectricity, prompting some to label it as 'one of the least-known properties of solid materials'," Martin added. "This work provides the most complete and detailed modeling and experimental study of this widely unknown region of materials and has direct implications for next generation devices."

Researchers found that reducing the dimensions of ferroelectrics increases their susceptibility to size- and strain-induced effects. The group's paper, "Effect of 90-degree domain walls and thermal expansion mismatch on the pyroelectric properties of epitaxial PbZr0.2Ti0.8O3 thin films," appears in the journal Physical Review Letters.

"What we did in this work was to develop a new approach to utilize and understand a class of materials important for all of these applications," Martin said. "By moving to a 'bottom-up' approach that produces nanoscale versions of these materials as thin films, we have observed, for the first time, that certain features, namely domain walls, can be incredibly important and even dominate the temperature-dependent response and performance of these materials."

According to J. Karthik, the first author on the group's paper, thin-film epitaxy has been developed to provide a set of parameters (e.g., film composition, epitaxial strain, electrical boundary conditions, and thickness) that allow for precise control of ferroelectrics and has been instrumental in understanding the physics of dielectric and piezoelectric effects.

"We investigated the contribution of 90º domain walls and thermal expansion mismatch to pyroelectricity in ferroelectric PbZr0.2Ti0.8O3 thin films, a widely used material whose bulk ferroelectric and piezoelectric properties are well understood," Karthik explained. As part of this work, Martin's Prometheus research group developed and applied the first phenomenological models to include extrinsic and secondary contributions to pyroelectricity in polydomain films and predict significant extrinsic contributions (arising from the temperature-dependent motion of domain walls) and large secondary contributions (arising from thermal expansion mismatch between the film and the substrate).

"We have also developed and applied a new phase-sensitive pyroelectric current measurement process to measure thin films for the first time and reveal a dramatic increase in the pyroelectric coefficient with increasing fraction of in-plane oriented domains and thermal expansion mismatch consistent with these models," Karthik said.

"By establishing an understanding of the science of these effects, with models to predict their performance, and demonstrated techniques to fabricate and utilize these properties in nanoscale versions of these materials, their properties can be effectively integrated into existing electronics," Martin said.

This research was supported by the Office of Naval Research, the Army Research Office, and the Air Force Office of Scientific Research.

Lane Martin | EurekAlert!
Further information:
http://www.illinois.edu

More articles from Physics and Astronomy:

nachricht Introducing the disposable laser
04.05.2016 | American Institute of Physics

nachricht New fabrication and thermo-optical tuning of whispering gallery microlasers
04.05.2016 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nuclear Pores Captured on Film

Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.

Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

New fabrication and thermo-optical tuning of whispering gallery microlasers

04.05.2016 | Physics and Astronomy

Introducing the disposable laser

04.05.2016 | Physics and Astronomy

A new vortex identification method for 3-D complex flow

04.05.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>