Determine why a certain type of crystal known as ammonium
dihydrogen phosphate, or ADP, behaves the way it does.
State University scientist solved 70 years-old crystal mystery
Florida, Oct. 22, 2007
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
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
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
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
"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
"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
"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.
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
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