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Electronics Detox: Leadfree material for ecofriendly gadgetry

Alexandra Goho

Scientists in Japan have created a new material that could someday replace toxic components in many electronic devices. With growing concern over the disposal of cell phones, computers, and other gadgets containing hazardous materials, the team proposes that its discovery will render future devices less harmful to the environment.

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HEAP OF TROUBLE. Many of the components in cell phones contain lead, which makes their disposal an environmental challenge. A new, leadfree piezoceramic could replace some lead-based components in a host of electronic devices.

AP/Wideworld

The innovation is a type of piezoceramic-a material that shrinks or swells when an electric field is applied. The ringers in cell phones, for instance, are made from piezoceramics that vibrate at high frequencies in response to an electric signal. The effect also works in reverse-squeeze a piezoceramic, and it generates an electric field. That produces a spark in a barbecue igniter, for instance. Sonar systems, fuel injectors, and many sensors also rely on these shape-changing materials.

Today, the most widely used piezoceramic is lead zirconium titanate (PZT). "It's the material of choice," says Harry Tuller of the Massachusetts Institute of Technology. It's also an environmental headache. Lead contributes 60 percent of the weight of PZT.

According to the New York-based environmental-research firm INFORM, consumers in the United States will collectively own some 500 million cell phones by 2005. Once discarded, these devices could release a total of 312,000 pounds of lead into the environment.

Countries in Europe and Asia are already adopting laws that require companies to recycle the electronic products they manufacture. Also, several programs in the United States have begun to collect cell phones and recycle their parts.

To tackle the problem at its source, researchers around the world have developed a number of leadfree piezoceramics, "but none as good as PZT," says Tuller. "That's been difficult to achieve."

Now, scientists at the Toyota R&D Laboratories in Nagakute and at the DENSO Corp. in Kariya report creating a new piezoceramic that's not only leadfree but in preliminary tests matches PZT's performance. "This is the best leadfree [piezoceramic] that I've seen," says Susan Trolier-McKinstry of Pennsylvania State University in State College. "It's pretty exciting."

The material is an alkaline niobate-based ceramic-a polycrystalline material containing mostly niobate, sodium, and potassium, along with minor amounts of lithium, tantalum, and antimony. The researchers engineered the material so it doesn't heat up after going through repeated cycles of shape changing. Thermal stability is required to ensure long-term stability of piezoceramics, says Trolier-McKinstry.

The Toyota and DENSO researchers describe their innovation in the Nov. 4 Nature. Coauthor Yasuyoshi Saito of Toyota says that he doesn't know when the new material might find its way into electronic devices. The researchers still need to resolve several technical issues related to mass production, he says.

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Letters:

I'm no fan of cell phones, but this seems to be an article about a solution looking for a problem. Presumably, cell phones would be disposed of in landfills and, therefore, not exactly "released" into the environment, as the article states.

In any case, the 312,000 pounds of lead in all cell phones owned in 2005 should be put into the context of the estimated 350 million pounds of lead released in 2002 by the coal and metal mining industries, or the 8.8 million pounds released by the electric-power-generation industry. Also, federal agencies estimate that about 6,000 million pounds of lead remain in 57 million houses in the United States.

John Coleman
Madison, WI

References:

Saito, Y., et al. 2004. Lead-free piezoceramics. Nature 432(Nov. 4):84–87. Abstract.

Further Readings:

Cross, E. 2004. Lead-free at last. Nature 432(Nov. 4):24–25.

Weiss, P. 2001. Some swell materials give up their secret. Science News 159(March 17):167. Available at Science News.

Sources:

Yasuyoshi Saito
Toyota Central R&D Laboratories, Inc.
Nagakute, Aichi, 480-1192
Japan

Susan Trolier-McKinstry
Department of Materials Science and Engineering
Pennsylvania State University
151 Materials Research Laboratory
University Park, PA 16802

Harry Tuller
Department of Materials Science and Engineering
Massachusetts Institute of Technology
Room 13-3126, 77 Massachusetts Avenue
Cambridge, MA 02139


From Science News, Volume 166, No. 19, November 6, 2004, p. 293.