Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

Effective Nanotechnology Innovations to Receive Mustafa Prize September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

Thin films

Beneq launches nFOG™ wet coating technology September 3rd, 2014

Picosun joins forces with IMEC for novel, industrial ALD applications August 25th, 2014

An Inkjet-Printed Field-Effect Transistor for Label-Free Biosensing August 11th, 2014

Advanced thin-film technique could deliver long-lasting medication: Nanoscale, biodegradable drug-delivery method could provide a year or more of steady doses August 6th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Sensors

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

First Colloid and Polymer Science Lecture awarded to Orlin D. Velev: Chemical engineer honored for outstanding research in colloid science September 12th, 2014

UT Arlington research uses nanotechnology to help cool electrons with no external sources September 11th, 2014

Development of Algorithm for Accurate Calculation of Average Distance Travelled by Low-Speed Electrons without Energy Loss that Are Sensitive to Surface Structure September 11th, 2014

Discoveries

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Announcements

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

Effective Nanotechnology Innovations to Receive Mustafa Prize September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

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

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

‘Small’ transformation yields big changes September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Simple, Cost-Effective Method Proposed for Synthesizing Zinc Oxide Nanopigments September 15th, 2014

Tools

Advanced Light Source Sets Microscopy Record| Berkeley Lab Researchers Achieve Highest Resolution Ever with X-ray Microscopy September 11th, 2014

Researchers Create World’s Largest DNA Origami September 11th, 2014

Development of Algorithm for Accurate Calculation of Average Distance Travelled by Low-Speed Electrons without Energy Loss that Are Sensitive to Surface Structure September 11th, 2014

How skin falls apart: The pathology of autoimmune skin disease is revealed at the nanoscale September 10th, 2014

Environment

Iranian Nano Scientists Create Flame-Resistant Polymers September 13th, 2014

NanoStruck has a High Recovery Rate on Mine Tailings: retrieval of up to 96% of Gold, 88% of Silver and 86% of Palladium September 12th, 2014

Nanostruck announces 87.6% recovery of 56 GMS/ton silver tailings samples September 12th, 2014

Boosting armor for nuclear-waste eating microbes September 12th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE