The solution to a 7-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.”

Source: Florida State University

Related stories:

Researchers Developing More Powerful Solar Cells
Sure, Iowa has its share of rainy, snowy and cloudy days. But look out the window. “We have a lot of sunlight,” said Vikram Dalal as sunshine lit up a late-summer morning and the south-facing windows of his office at Iowa State University’s Applied Sciences Complex.
Ultrathin films promise a multitude of uses
Imagine a special coating that can be applied to any of a number of surfaces. With its application, carpets, furniture and clothing become super-resistant to stains; automobile bodies are impermeable to water and rust; stents put in place during heart surgery no longer are susceptible to tissue growth that can restrict blood flow; and cell cultures are more easily produced in the laboratory.
Scientific Surprise Greets Researchers at Higher Magnetic Fields
Research performed by a team at Florida State University's National High Magnetic Field Laboratory suggests that the benefits of building higher-field superconducting magnets likely will far outweigh the costs of building them.
Using nano-magnets to enhance medical imaging
Nanoscale magnets in the form of iron-containing molecules might be used to improve the contrast between healthy and diseased tissue in magnetic resonance imaging (MRI)—as long as the concentration of nanomagnets is carefully managed—according to a new report by researchers at the National Institute of Standards and Technology and collaborators. Molecular nanomagnets are a new class of MRI contrast agents that may offer significant advantages, such as versatility in design, over the compounds used today.
New Material May Lead To Advances In Quantum Computing
Scientists at Florida State University’s National High Magnetic Field Laboratory and the university’s Department of Chemistry and Biochemistry have introduced a new material that could be to computers of the future what silicon is to the computers of today.

News discussion:

General Science news