Tag Archives: Zuo-Guang Ye

Getting to know your piezoelectrics

It took me a couple of tries before I could see the butterfly in the neutron scattering image (on the left), which illustrates work undertaken in an attempt to better understand piezoelectrics (found in hard drives, loud speakers, etc.) by researchers at Simon Fraser University (Vancouver area, Canada) and the US National Institute of Standards and Technology.

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive "butterfly" shape quite different from that of PZT, in which the atoms are more regularly spaced. Credit: NIST

These two neutron scattering images represent the nanoscale structures of single crystals of PMN and PZT. Because the atoms in PMN deviate slightly from their ideal positions, diffuse scattering results in a distinctive “butterfly” shape quite different from that of PZT, in which the atoms are more regularly spaced.
Credit: NIST

A Jan. 30, 2014 news release on EurekAlert (also found on on the NIST website where it’s dated Jan. 29, 2014) describes piezoelectrics,

Piezoelectrics—materials that can change mechanical stress to electricity and back again—are everywhere in modern life. Computer hard drives. Loud speakers. Medical ultrasound. Sonar. Though piezoelectrics are a widely used technology, there are major gaps in our understanding of how they work. Now researchers at the National Institute of Standards and Technology (NIST) and Canada’s Simon Fraser University believe they’ve learned why one of the main classes of these materials, known as relaxors, behaves in distinctly different ways from the rest and exhibit the largest piezoelectric effect. And the discovery comes in the shape of a butterfly. …

The news release goes on to explain piezoelectrics and provide details about how the researchers made their discovery,

The team examined two of the most commonly used piezoelectric compounds—the ferroelectric PZT and the relaxor PMN—which look very similar on a microscopic scale. Both are crystalline materials composed of cube-shaped unit cells (the basic building blocks of all crystals) that contain one lead atom and three oxygen atoms. The essential difference is found at the centers of the cells: in PZT these are randomly occupied by either one zirconium atom or one titanium atom, both of which have the same electric charge, but in PMN one finds either niobium or manganese, which have very different electric charges. The differently charged atoms produce strong electric fields that vary randomly from one unit cell to another in PMN and other relaxors, a situation absent in PZT.

“PMN-based relaxors and ferroelectric PZT have been known for decades, but it has been difficult to identify conclusively the origin of the behavioral differences between them because it has been impossible to grow sufficiently large single crystals of PZT,” says the NIST Center for Neutron Research (NCNR)’s Peter Gehring. “We’ve wanted a fundamental explanation of why relaxors exhibit the greatest piezoelectric effect for a long time because this would help guide efforts to optimize this technologically valuable property.”

A few years ago, scientists from Simon Fraser University found a way to make crystals of PZT large enough that PZT and PMN crystals could be examined with a single tool for the first time, permitting the first apples-to-apples comparison of relaxors and ferroelectrics. That tool was the NCNR’s neutron beams, which revealed new details about where the atoms in the unit cells were located. In PZT, the atoms sat more or less right where they were expected, but in the PMN, their locations deviated from their expected positions—a finding Gehring says could explain the essentials of relaxor behavior.

“The neutron beams scatter off the PMN crystals in a shape that resembles a butterfly,” Gehring says. “It gives a characteristic blurriness that reveals the nanoscale structure that exists in PMN—and in all other relaxors studied with this method as well—but does not exist in PZT. It’s our belief that this butterfly-shaped scattering might be a characteristic signature of relaxors.”

Additional tests the team performed showed that PMN-based relaxors are over 100 percent more sensitive to mechanical stimulation compared to PZT, another first-time measurement. Gehring says he hopes the findings will help materials scientists do more to optimize the behavior of piezoelectrics generally.

Here’s a citation for the researchers’ paper,

Role of random electric fields in relaxors by Daniel Phelan, Christopher Stock, Jose A. Rodriguez-Rivera, Songxue Chia, Juscelino Leão, Xifa Long, Yujuan Xie, Alexei A. Bokov, Zuo-Guang Ye, Panchapakesan Ganesh, and Peter M. Gehring. Proceedings of the National Academy of Sciences, Jan. 21, 2014. DOI:10.1073/pnas.1314780111

This paper is behind a paywall.

Canadian Society for Chemistry honours Québec nanoscientist Federico Rosei

Dr. Federico Rosei’s name has graced this blog before, most recently in a June 15, 2010 posting about an organic nanoelectronics project. Late last week, Québec’s Institut national de la recherche scientifique (INRS) announced that Rosei will be honoured by the Canadian Society for Chemistry at  the 2014 Canadian Chemistry Conference (from the January 24, 2014 news release on EurekAlert),,

The Canadian Society for Chemistry (CSC) has bestowed its 2014 Award for Research Excellence in Materials Chemistry on Professor Federico Rosei, director of the INRS Énergie Matériaux Télécommunications research centre, in recognition of his exceptional contributions to the field. Professor Rosei will be honoured at the society’s annual conference, which will take place June 1 to 5, 2014, in Vancouver.

In conjunction with this honour, Federico Rosei has been invited to speak at this important scientific conference and to take part in a lecture tour of Canadian universities located outside major cities.

Professor Rosei has been widely honoured for his research on nanomaterial properties and their applications. He has received numerous awards and distinctions, including the 2013 Herzberg Medal from the Canadian Association of Physicists, the Brian Ives Lectureship Award from ASM Canada, the 2011 Rutherford Memorial Medal in Chemistry from the Royal Society of Canada, and the Alexander von Humboldt Foundation’s 2010 Friedrich Wilhelm Bessel Research Award. He is also a fellow of the American Association for the Advancement of Science; the Institute of Physics; the Royal Society of Chemistry; the Institute of Materials, Minerals and Mining; the Institute of Engineering and Technology; and the Institute of Nanotechnology in the U.K.; the Engineering Institute of Canada; and the Australian Institute of Physics. In addition, Professor Rosei is a Senior Member of the Institute of Electrical and Electronics Engineers (IEEE) and the Society for Photo-Image Engineers (SPIE), and a member of Sigma Xi (scientific research society) and the Global Young Academy.

Please join us in extending our congratulations to Professor Rosei!


The Canadian Society for Chemistry

The Canadian Society for Chemistry (CSC) is a not-for-profit professional association that unites chemistry students and professionals who work in industry, academia, and government. Recognized by the International Union of Pure and Applied Chemistry (IUPAC), the CSC awards annual prizes and scholarships in recognition of outstanding achievements in the chemical sciences.

About INRS

Institut national de recherche scientifique (INRS) is a graduate research and training university. As Canada’s leading university for research intensity in its class, INRS brings together some 150 professors and close to 700 students and postdoctoral fellows in its centres in Montreal, Quebec City, Laval, and Varennes. As active providers of fundamental research essential to the advancement of science in Quebec as well as internationally, INRS research teams also play a critical role in developing concrete solutions to problems that our society faces.

The French language version of the news release: de l’actualité le 23 janvier 2014, par Stéphanie Thibault (Note: Links have been removed from the excerpt),

Le professeur Federico Rosei du Centre Énergie Matériaux Télécommunications de l’INRS est récipiendaire du Prix d’excellence en chimie des matériaux 2014. La Société canadienne de chimie reconnaît ainsi sa contribution exceptionnelle dans ce domaine. Le professeur Rosei sera honoré lors du congrès annuel de la Société qui aura lieu du 1er au 5 juin 2014 à Vancouver.

À titre de lauréat, le professeur Rosei sera conférencier invité à cette importante rencontre scientifique et participera à une tournée de conférences qui l’amènera dans des universités canadiennes situées hors des grandes villes.

I have not found any specific details about Dr. Rosei’s upcoming chemistry lecture tour of universities.

The conference where Dr. Rosei will be honoured is the 97th annual Canadian Chemistry Conference and Exhibition. It is being hosted by Simon Fraser University (SFU), located in the Vancouver region. While the conference programme is not yet in place there’s a hint as to what will be offered in the conference chair’s Welcome message,

On behalf of the Organizing Committee, I am delighted to welcome all the delegates and their guests to Vancouver, British Columbia, for the 97th Canadian Chemistry Conference and Exhibition that will take place from June 1 to 5, 2014. This is Canada’s largest annual event devoted to the science and practice of chemistry, and it will give participants a platform to exchange ideas, discover novel opportunities, reacquaint with colleagues, meet new friends, and broaden their knowledge. The conference will held at the new Vancouver Convention Centre, which is a spectacular, green-designed facility on the beautiful waterfront in downtown Vancouver.

The theme of the CSC 2014 Conference is “Chemistry from Sea to Sky”; it will broadly cover all disciplines of chemistry from fundamental research to “blue sky” applications, highlight global chemical scientific interactions and collaborations, and feature the unique location, culture and beautiful geography (the Coastal Mountains along the ocean’s edge of Howe Sound) of British Columbia and Vancouver.

We are pleased to have Professor Shankar Balasubramanian (University of Cambridge, UK) and Professor Klaus Müllen (Max Planck Institute for Polymer Research, Mainz, Germany) as the plenary speakers. In addition to divisional symposia, the scientific program also includes several jointly organized international symposia, featuring Canada and each of China, Germany, Japan, Korea, Switzerland and the USA. This new type of symposium at the CSC aims to highlight research interests of Canadians in an international context. Interactions between chemists and TRIUMF (the world’s largest cyclotron, based in Vancouver) will also be highlighted via a special “Nuclear and Radiochemistry” Divisional Program.

All of the members of the local Organizing Committee from Simon Fraser University wish you a superb conference experience and a memorable stay in Vancouver. Welcome to Vancouver! Bienvenue à Vancouver!

Zuo-Guang Ye, Conference Chair
Department of Chemistry
Simon Fraser University
Burnaby, British Columbia

Conference abstracts are being accepted until February 17, 2014 (according to the conference home page). Dr. Shankar Balasubramanian was last mentioned (one of several authors of a paper) here in a July 22, 2013 posting titled: Combining bacteriorhodopsin with semiconducting nanoparticles to generate hydrogen.