Determine why a certain type of crystal known as ammonium dihydrogen phosphate, or ADP, behaves the way it does.

NRI Florida State University scientist solved 70 years-old crystal mystery

 

Florida, Oct. 22, 2007
Sant Singh

NRI Naresh S. Dalal, Professor of Chemistry and Biochemistry at Florida State University has solved a 70 years old scientific mystery for the development of more powerful computer memories and lasers.

Barry Ray wrote- Solution to a seven-decade mystery is crystal clear to FSU chemist. A Florida State University researcher has helped solve a scientific mystery that stumped chemists for nearly seven decades. In so doing, his team's findings may lead to the development of more-powerful computer memories and lasers.

Naresh S. Dalal, the Dirac Professor of Chemistry and Biochemistry at FSU, recently collaborated with three colleagues, Jorge Lasave, Sergio Koval and Ricardo Migoni, all of the Universidad Nacional de Rosario in Argentina, to determine why a certain type of crystal known as ammonium dihydrogen phosphate, or ADP, behaves the way it does.

"ADP was discovered in 1938," Dalal said. "It was observed to have some unusual electrical properties that weren't fully understood—and for nearly 70 years, scientists have been perplexed by these properties. Using the supercomputer at SCRI (FSU's Supercomputer Computations Research Institute), we were able to perform in-depth computational analyses that explained for the very first time what causes ADP to have these unusual properties."

ADP, like many crystals, exhibits an electrical phenomenon known as ferroelectricity. Ferroelectric materials are analogous to magnets in that they maintain a positively charged and a negatively charged pole below a certain temperature that is characteristic for each compound.

"Ferroelectric materials can stay in a given state of charge for a long time—they retain their charge after the external electrical source is removed," Dalal said. "This has made ADP and other materials like it very useful for storing and transmitting data.

ADP is commonly used in computer memory devices, fiber optic technology, lasers and other electro-optic applications."

What researchers found perplexing about ADP was that it often displays a very different electrical phase—one known as antiferroelectricity.

"With antiferroelectricity, one layer of molecules in a crystal has a plus and a minus pole, but in the next layer, the charges are reversed," Dalal said. "You see this reversal of charges, layer by layer, throughout the crystal."

Using the supercomputer at SCRI enabled Dalal and his colleagues to perform numerous highly complex calculations that couldn't be duplicated in a laboratory environment. For example, they were able to theoretically alter the angles of ADP's ammonium ions and then measure the effects on the crystal's electrical charge. That approach ultimately led to their solution to the seven-decade mystery.

"We found that the position of the ammonium ions in the compound, as well as the presence of stresses or defects in the crystal, determine whether it behaves in a ferroelectric or antiferroelectric manner," Dalal said.

The team's research is important for two main reasons, Dalal said: "First, this allows us to further understand how to design new materials with both ferroelectric and antiferroelectric properties. Doing so could open new doors for computer memory technology—and possibly play a role in the development of quantum computers.

"Second, our research opens up new ways of testing materials," Dalal said. "Using supercomputers, we can quickly perform tests to see how materials would react under a variety of conditions. Many such tests can't even be performed in the lab."

A paper describing Dalal, Lasave and Migoni's findings was published recently in the prestigious scientific journal Physical Review Letters. Titled "Origin of Antiferroelectricity in NH4H2PO4 from First Principles," it can be viewed online here.

 

FSU professor Naresh Dalal to receive 2007 Southern Chemist Award

Naresh S. Dalal, the Dirac Professor of Chemistry and Biochemistry at Florida State University, has been selected to receive the 2007 Southern Chemist Award from the Memphis Section of the American Chemical Society.

The award honors "an outstanding researcher who has brought recognition to the South," specifically the states of Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee and Virginia. A medal and honorarium will be presented to Dalal at a meeting of the Memphis Section of the American Chemical Society in December.

"It always is a great honor to be recognized by one's peers in such a manner," Dalal said of the award. "I'm particularly pleased because this award recognizes the work I have done since I moved to Florida State in 1995."

Dalal has made notable contributions to spectroscopic techniques spanning frequencies from a few hertz to several terahertz over more than three decades of pioneering research in magnetic resonance spectroscopy, mainly electron magnetic resonance. Such research has novel applications to a wide range of problems, ranging from free radicals in toxicology and carcinogenesis to ferroelectric and magnetic phase transitions in quantum solids, quantum dots, quantum computing and high-temperature superconductivity. Over the course of his career, Dalal has been a prodigious writer and researcher, publishing scholarly articles in more than 350 publications.

"We at FSU and the National High Magnetic Field Laboratory are of course delighted to hear of Professor Dalal's latest peer recognition," said Alan G. Marshall, the Kasha Professor of Chemistry at FSU and director of the Ion Cyclotron Resonance Program at the magnet lab. "This one is especially remarkable because it is based on research conducted in the Southern geographic region--in Naresh's case, only since he joined the FSU Department of Chemistry and Biochemistry 12 years ago."

Dalal came to FSU and the National High Magnetic Field Laboratory in 1995 from West Virginia University, where he held the Centennial Professor Chair of Chemistry. He chaired the FSU Department of Chemistry and Biochemistry from 1999 to 2007, and currently serves as an assistant dean in FSU's College of Arts & Sciences.

Earlier this year, Dalal was recognized as the top chemist in Florida by the the Florida Section of the American Chemical Society, which bestowed up on him its annual Florida Award (www.fsu.com/pages/2007/03/15/FloridaAwardInChemistry.html). He also was named a fellow of the American Physical Society in 1999, and in 2003 was designated a Distinguished Research Professor, which recognizes outstanding research and/or creative activity, at FSU.

Dalal is the fifth faculty member in FSU's Department of Chemistry and Biochemistry to receive the Southern Chemist Award, joining Gregory Choppin (1971), Michael Kasha (1974), Earl Frieden (1987) and Alan G. Marshall (2004).

Source- BY BARRY RAY

National High Magnetic Field Laboratory Personnel

Education

1962 B.S. Physics (Honors), Panjab University, India

1963 M.S. Physics, Panjab University, India

1971 Ph.D. Physical Chemistry, University of British Columbia, Vancouver, Canada

Professional Experience

• 1972-74, Killam Fellow, University of British Columbia
• 1975-76, IBM World-Trade Visiting Research Fellow, San Jose, CA
• 1976-77, National Research Council Fellow, Ottawa, Canada
• 1978-94, Asst. Prof./Assoc. Prof./Professor of Chemistry, West Virginia University
• 1995-96, Centennial Professor, Chemistry Department, West Virginia University
• 1995-, Editorial Board: Journal of Magnetic Resonance
• 1996-, Professor, Chemistry Department, Florida State University
• 1999-, Chairman, Department of Chemistry and Biochemistry, Florida State University
• 2002., Dirac Professor of Chemistry and Biochemistry, Florida State University
  

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  Awards, Honors & Service:
  2007 Florida Award from the American Chemical Society (2007)
  2007 Southern Chemist Award from the Memphis Section of the American Chemical Society (2007)
  Distinguished Research Professor Award, FSU (2003)