Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Berkeley Researchers Take the Lead Out of Piezoelectrics

This high-resolution electron micrograph shows the the boundaries between rhombohedral (R phase) and tetragonal (T phase) regions – indicated by dashed lines - in a thin film of bismuth ferrite under epitaxial strain. A smooth transition between phases is observed with no dislocations or defects at the interface. The image was produced on TEAM 0.5 at the National Center for Electron Microscopy.
This high-resolution electron micrograph shows the the boundaries between rhombohedral (R phase) and tetragonal (T phase) regions – indicated by dashed lines - in a thin film of bismuth ferrite under epitaxial strain. A smooth transition between phases is observed with no dislocations or defects at the interface. The image was produced on TEAM 0.5 at the National Center for Electron Microscopy.

Abstract:
By applying just the right compression to thin films of bismuth ferrite, Berkeley Lab researchers have produced a lead-free alternative to the current crop of piezoelectric materials.

Berkeley Researchers Take the Lead Out of Piezoelectrics

Berkeley, CA | Posted on November 25th, 2009

There is good news for the global effort to reduce the amount of lead in the environment and for the growing array of technologies that rely upon the piezoelectric effect. A lead-free alternative to the current crop of piezoelectric materials has been identified by researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC), Berkeley.

The key to this success is the use of bismuth ferrite, a compound with a perovskite crystal structure, meaning it has crystal planes of oxygen and bismuth atoms alternating with planes of oxygen and iron atoms. These planes can move relative to one other when the proper strain is applied. The research team discovered that the piezoelectric effect in bismuth ferrite becomes significantly enhanced in response to the application of epitaxial strain -compression in the direction of its crystal planes.

"We have demonstrated that epitaxial strain can be used to create a large piezoelectric responses in thin films of bismuth ferrite," says Ramamoorthy Ramesh, a materials scientist who led this research. "The piezoelectric effect is reversible when the strain is relaxed."

Ramesh holds joint appointments with Berkeley Lab's Materials Sciences Division and UC Berkeley's Department of Materials Science and Engineering and the Department of Physics. He is the senior author on a paper published in the journal Science entitled: "A Strain-Driven Morphotropic Phase Boundary in BiFeO3."

Co-authoring the paper with Ramesh were Robert Zeches, Marta-Dacil Rossell, Jinxing Zhang, Alison Hatt, Qing He, Chan-Ho Yang, Amit Kumar, Chih-Hubng Wang, Alexander Melville, Carolina Adamo, Guang Sheng, Ying-Hao Chu, Jon Ihlefeld, Rolf Erni, Claude Ederer, Venkatraman Gopalan, Long-Qing Chen, Darrell Schlom, Nicola Spaldin and Lane Martin.

"In principle, the strain-driven piezoelectric effect we have observed in bismuth ferrite should be generic to other lead-free perovskites as well," Ramesh says, "akin to chemically driven effects that are now well established in the manganites, cuprates and relaxors."

Piezoelectric materials, as a result of their unique crystal structures, are able to couple mechanical and electrical properties. Place a mechanical strain on a piezoelectric and an electric charge is generated across its surface. Subject a piezoelectric to an electric charge and its shape becomes deformed. The electromechanical properties of piezoelectric materials have made them valuable components in a broad range of devices, including sensors, actuators and transducers. They are especially valuable for medical ultrasounds and for non-destructive testing of roads and bridges.

The most widely used piezoelectric materials today are lead-based perovskite compounds, especially lead zirconate titanate (PZT). These perovskites display superior piezoelectric properties in areas where the phase of their crystal structure abruptly changes. Such areas, known as morphotropic phase boundaries, are produced via complex chemical alloying of a PZT-type perovskite's metal and oxide constituents. While the technology is well established, lead is a potent neurotoxin that poses a serious threat to human health, especially children, and to the environment.

"We have produced the piezoelectric effect by taking thin films of bismuth ferrite and applying a huge epitaxial strain," says Robert Zeches, a member of Ramesh's UC Berkeley research group who was the first author on the Science paper. "The bismuth ferrite wants to be in a rhombohedral phase but the epitaxial strain forces it into a tetragonal phase, creating a morphotropic phase boundary."

If the strain is removed, the bismuth ferrite crystal structure reverts back to its original rhombohedral-like phase, Zeches says. By alternating between squeezing and relaxing, the researchers can shuttle the material back and forth between the two phases.

Ramesh joking observed that, "Inducing materials into such a schizophrenic state can be the key to obtaining exotic behavior."

Ramesh and his group are now testing their strain-driven piezoelectric technique on other perovskites. They are also exploring the use of epitaxial strain to generate other phenomena such as magnetoresistance. Noting that the reversible phase changes in the bismuth ferrite films are accompanied by changes of a few nanometers in the height of the sample surface - a substantial change on this scale - Ramesh and his colleagues believe their results make bismuth ferrite an attractive candidate for data storage applications.

The bismuth ferrite films and morphotropic phase boundaries created by epitaxial strain were characterized using TEAM 0.5, a unique transmission electron microscope created as part of the larger TEAM project. The acronym stands for Transmission Electron Aberration-corrected Microscope. TEAM 0.5 is capable of producing images with half angstrom resolution, which is less than the diameter of a single hydrogen atom. TEAM 0.5 and its successor, TEAM 1.0, are located at Berkeley Lab's National Center for Electron Microscopy (NCEM) - a DOE national user facility and the country's premier center for electron microscopy and microcharacterization.

"The resolution of TEAM 0.5, which is currently the highest in the world for an electron microscope, made it possible for us to image the atomic structure of both the tetragonal and rhombohedral phases and their interfaces," says Ramesh.

This research was supported by the U.S. Department of Energy's Office of Science.

For more information on the research of Ramamoorthy Ramesh, visit his Website at www.lbl.gov/msd/investigators/investigators_all/ramesh_investigator.html

####

About Berkeley Lab
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California.

For more information, please click here

Contacts:
Lynn Yarris
(510) 486-5375

Copyright © Berkeley Lab

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

GLOBALFOUNDRIES Unveils Vision and Roadmap for Next-Generation 5G Applications: Technology platforms are uniquely positioned to enable a new era of ‘connected intelligence’ with the transition to 5G September 20th, 2017

GLOBALFOUNDRIES Delivers Custom 14nm FinFET Technology for IBM Systems: Jointly developed 14HP process is world’s only technology that leverages both FinFET and SOI September 20th, 2017

GLOBALFOUNDRIES Introduces New 12nm FinFET Technology for High-Performance Applications September 20th, 2017

Thin films

Rice University chemists make laser-induced graphene from wood July 31st, 2017

Graduate Students from Across the Country Attend Hands-on NanoCamp: Prominent scientists Warren Oliver, Ph.D., and George Pharr, Ph.D., presented a weeklong NanoCamp for hand-picked graduate students across the United States July 26th, 2017

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

Thinking thin brings new layering and thermal abilities to the semiconductor industry: In a breakthrough for the semiconductor industry, researchers demonstrate a new layer transfer technique called "controlled spalling" that creates many thin layers from a single gallium nitride July 11th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

New insights into nanocrystal growth in liquid: Understanding process that creates complex crystals important for energy applications September 14th, 2017

Magnetic cellular 'Legos' for the regenerative medicine of the future September 12th, 2017

Sensors

Leti Develops Proof of Concept to Test Wireless Systems in Aircraft: Will Present Results of Joint Project at AeroTech Conference And Exhibition in Fort Worth, Texas, Sept. 26-28 September 20th, 2017

Research shows how DNA molecules cross nanopores: Study could inform biosensors, manufacturing, and more September 5th, 2017

Leti and Partners in PiezoMAT Project Develop New Fingerprint Technology for Highly Reliable Security and ID Applications: Ultra-high Resolution Pressure Sensing Uses Matrices of Vertical Piezoelectric Nanowire To Reconstruct the Smallest Features of Human Fingerprints September 5th, 2017

New results reveal high tunability of 2-D material: Berkeley Lab-led team also provides most precise band gap measurement yet for hotly studied monolayer moly sulfide August 26th, 2017

Discoveries

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

A new approach to ultrafast light pulses: Unusual fluorescent materials could be used for rapid light-based communications systems September 19th, 2017

Announcements

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

GLOBALFOUNDRIES Delivers Custom 14nm FinFET Technology for IBM Systems: Jointly developed 14HP process is world’s only technology that leverages both FinFET and SOI September 20th, 2017

GLOBALFOUNDRIES Introduces New 12nm FinFET Technology for High-Performance Applications September 20th, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Physicists develop new recipes for design of fast single-photon gun Physicists develop high-speed single-photon sources for quantum computers of the future September 21st, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

A new approach to ultrafast light pulses: Unusual fluorescent materials could be used for rapid light-based communications systems September 19th, 2017

Tools

Graphene based terahertz absorbers: Printable graphene inks enable ultrafast lasers in the terahertz range September 13th, 2017

Chemical hot spots: Scanning tunneling microscopy measurements identify active sites on catalyst surfaces September 7th, 2017

Phenom-World selects Deben to supply a tensile stage as an accessory to their range of desktop SEMs August 29th, 2017

New results reveal high tunability of 2-D material: Berkeley Lab-led team also provides most precise band gap measurement yet for hotly studied monolayer moly sulfide August 26th, 2017

Environment

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

High-tech electronics made from autumn leaves: New process converts biomass waste into useful electronic devices August 30th, 2017

Nanoparticles pollution rises 30 percent when flex-fuel cars switch from bio to fossil: Study carried out in São Paulo, home to the world's largest flex fuel urban fleet, shows increase of ultrafine particulate matter when ethanol prices rose and consumption fell August 28th, 2017

A more complete picture of the nano world August 24th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project