Featured Research

from universities, journals, and other organizations

Residual Stress In Piezoelectric Ceramics Can Be Reduced, Put To Work

Date:
September 6, 2000
Source:
University Of Illinois At Urbana-Champaign
Summary:
By applying a mechanical bending stress to offset the effects of residual stress in a piezoelectric ceramic thin film, researchers at the University of Illinois have found a way to significantly enhance the film's performance.

CHAMPAIGN, Ill. -- By applying a mechanical bending stress to offset the effects of residual stress in a piezoelectric ceramic thin film, researchers at the University of Illinois have found a way to significantly enhance the film's performance.

Related Articles


"Understanding the effects of residual stress in piezoelectric ceramic thin films is critical for their design and optimization as smart materials," said Nancy Sottos, a professor of theoretical and applied mechanics at the UI. "Not only can we greatly improve their performance as tiny sensors and actuators in microelectromechanical (MEMS) devices, we can also put the effects of residual stress to work in a unique patterning process to better incorporate these materials on electronic chips."

In previous work, Sottos and graduate research assistant Lei Lian found that as the ceramic films became thinner, the desired piezoelectric response also became smaller. Stresses within the films were thought to be primarily responsible.

Significant stresses build up in piezoelectric thin-film structures during the fabrication process, Sottos said. "There are intrinsic stresses caused by shrinkage and densification during the drying and firing stages, and there are extrinsic stresses that are induced upon cooling due to the mismatch between the thermoelastic properties of the film and substrate. As the films become thinner and thinner, the residual stress affects the piezoelectric properties more and more."

To further explore the connection between residual stress and piezoelectric response, Sottos and Lian exposed lead-zirconate-titanate thin films to varying amounts of mechanical stress. By applying a small mechanical load in the opposite direction to the tensile stress, they could relieve some of the residual stress in the film. The film's piezoelectric response was then recorded with a high-resolution, laser Doppler heterodyne interferometric measuring technique.

"The film's response increased significantly with the application of a compressive bending stress," Sottos said. "A 10-pecent reduction in the residual stress netted a 30-percent increase in displacement."

In practice, it may be possible to compensate for the residual stress and recover film response by changing stress states during processing or by applying a mechanical deformation, Sottos said. It's also possible to put the residual stress to work in patterning the films for use on integrated circuits.

"It is difficult to selectively etch a ceramic, so standard subtractive chip processing techniques won't work well for some smart materials," Sottos said. "But, methods to first pattern a substrate with a special polymeric monolayer and then lay down the ceramic film have recently been developed at Illinois. The film will adhere to the exposed substrate, but not to the monolayer. Residual stress induced in the film during drying will cause it to crack off the monolayer with extremely clean edges."

The researchers presented their latest findings at the International Congress of Theoretical and Applied Mechanics, held Aug. 27 to Sept. 2 in Chicago.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Residual Stress In Piezoelectric Ceramics Can Be Reduced, Put To Work." ScienceDaily. ScienceDaily, 6 September 2000. <www.sciencedaily.com/releases/2000/09/000904122612.htm>.
University Of Illinois At Urbana-Champaign. (2000, September 6). Residual Stress In Piezoelectric Ceramics Can Be Reduced, Put To Work. ScienceDaily. Retrieved April 18, 2015 from www.sciencedaily.com/releases/2000/09/000904122612.htm
University Of Illinois At Urbana-Champaign. "Residual Stress In Piezoelectric Ceramics Can Be Reduced, Put To Work." ScienceDaily. www.sciencedaily.com/releases/2000/09/000904122612.htm (accessed April 18, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, April 18, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

At Least 15 Injured in a California Natural Gas Pipeline Explosion

At Least 15 Injured in a California Natural Gas Pipeline Explosion

Reuters - US Online Video (Apr. 18, 2015) At least 15 injred after natural gas transmission line ruptures in Fresno, California. Julie Noce reports. Video provided by Reuters
Powered by NewsLook.com
NASA Electric Rover Goes for a Spin

NASA Electric Rover Goes for a Spin

Reuters - Innovations Video Online (Apr. 17, 2015) NASA&apos;s prototype electric buggy could influence future space rovers and conventional cars. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Scientists Create Self-Powering Camera

Scientists Create Self-Powering Camera

Reuters - Innovations Video Online (Apr. 17, 2015) American scientists build a self-powering camera that captures images without using an external power source, allowing it to operate indefinitely in a well-lit environment. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
The State Of Virtual Reality

The State Of Virtual Reality

Newsy (Apr. 17, 2015) Virtual Reality is still a young industry. What’s on offer and what should we expect from our immersive new future? Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins