NRI scientist solves 7-decade-old crystal mystery

November 14th, 2007 - 2:34 am ICT by admin  
Prof. Naresh S. Dalal from the Florida State University and his co-researchers from the Universidad Nacional de Rosario in Argentina, tried to determine why the crystal known as ammonium dihydrogen phosphate, or ADP, displays certain unusual electrical properties.

“ADP was discovered in 1938. 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,” said Prof. Dalal.

“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,” he said.

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. This has made ADP and other materials like it very useful for storing and transmitting data,” said Prof. Dalal, a MS in Physics from Punjab University, India.

ADP, crystals, which have applications in computer memory, laser and fibre optic technology, is commonly used in computer memory devices, fibre optic technology, lasers and other electro-optic applications.

What Prof. Dalal and his team found f perplexing was that ADP often displayed 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. You see this reversal of charges, layer by layer, throughout the crystal,” said Prof. Dalal.

“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,” he said.

Prof. Dalal said the team’s research was important for two main reasons.

First, this allowed them 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,” said Prof. Dalal.

“Second, our research opens up new ways of testing materials. 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,” he said.

Co-researchers on the study were Jorge Lasave, Sergio Koval and Ricardo Migoni.

A paper describing their research was published recently in the prestigious scientific journal Physical Review Letters. (ANI)

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