Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Researchers identify pressure effects on nanomaterials

Fluorescence from CdSe quantum dot solids in environments varying from stable to high unstable show that small deviations from uniform stress distribution greatly affect the electronic properties. The blue represents cadmium, the yellow represents selenium and the red represents a cloud of electrons in their excited state.
Image by Sebastien Hamel/LLNL
Fluorescence from CdSe quantum dot solids in environments varying from stable to high unstable show that small deviations from uniform stress distribution greatly affect the electronic properties. The blue represents cadmium, the yellow represents selenium and the red represents a cloud of electrons in their excited state. Image by Sebastien Hamel/LLNL

Abstract:
Transistors, lasers and solar-energy conversion devices may be easier to manipulate because of recent research by Lawrence Livermore National Laboratory scientists.

Researchers identify pressure effects on nanomaterials

LIVERMORE, CA | Posted on May 7th, 2008

The researchers defined the role high pressure plays in precisely tuning the fundamental properties of nanomaterials and, in particular, nanoparticle assemblies that are important for device applications.

The team, made up of LLNL scientists Christian Grant, Jonathan Crowhurst, Sebastien Hamel, Natalia Zaitseva and former LLNL researcher Andrew Williamson (now at Physic Ventures), subjected quantum dot solids (in this case assemblies of cadmium selenide, or CdSe, nanocrystals) to very high static pressures on the order of 70,000 atmospheres and studied in-situ their response using a laser-based luminescence technique. A quantum dot is a semiconductor whose electrons are confined in all three spatial dimensions.

"We closely compared our results with theoretical calculations," Grant said. "These results were completely consistent with our experimental observations."

But when they applied nonuniform pressure, the results were quite different.

It led to large shifts in the energy associated with the very strong fluorescence of CdSe. CdSe, it was found, is extremely sensitive to the local stress state.

The typical length of quantum dots, which are anywhere in size from one to several hundred nanometers, have chemical and physical properties that are substantially different from those of their bulk and molecular counterparts. (A nanometer is one-billionth of a meter).

Quantum dots can be close-packed into quantum dot solids (QDSs). These nanomaterials can yield insight not only into particle-particle coupling but also tell a story of the evolution of their electronic properties from individual dots and the collective solid.

The Livermore team measured QDSs in several different pressure media, including a liquid and various solid or glassy but still fairly soft media. In addition, they compressed the material directly. Depending on the medium, they observed a steady increase in energy as a function of pressure (uniform pressure case) or after an initial increase, a flattening or even decrease in energy (non-uniform pressure case).

"High pressure provides insight into the fundamental properties of nanoparticles, which can be drastically different from the corresponding bulk material," Grant said.

For example the structural phase transition that occurs in bulk CdSe occurs at much lower pressures than in the case of the QDSs.

The research appears in the June issue of the journal Small.

####

About Lawrence Livermore National Laboratory
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

For more information, please click here

Contacts:
Anne M. Stark
Phone: (925) 422-9799
E-mail:

Copyright © Lawrence Livermore National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

A step closer to understanding quantum mechanics: Swansea Universityís physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Strange but true: turning a material upside down can sometimes make it softer October 20th, 2017

Leti Coordinating Project to Develop Innovative Drivetrains for 3rd-generation Electric Vehicles: CEA Techís Contribution Includes Litenís Knowhow in Magnetic Materials and Simulation And Letiís Expertise in Wide-bandgap Semiconductors October 20th, 2017

Chip Technology

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

MIPT scientists revisit optical constants of ultrathin gold films October 20th, 2017

Bringing the atomic world into full color: Researchers turn atomic force microscope measurements into color images October 19th, 2017

Spin current detection in quantum materials unlocks potential for alternative electronics October 15th, 2017

Discoveries

A step closer to understanding quantum mechanics: Swansea Universityís physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

Strange but true: turning a material upside down can sometimes make it softer October 20th, 2017

Announcements

A step closer to understanding quantum mechanics: Swansea Universityís physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Strange but true: turning a material upside down can sometimes make it softer October 20th, 2017

Leti Coordinating Project to Develop Innovative Drivetrains for 3rd-generation Electric Vehicles: CEA Techís Contribution Includes Litenís Knowhow in Magnetic Materials and Simulation And Letiís Expertise in Wide-bandgap Semiconductors October 20th, 2017

Energy

New nanomaterial can extract hydrogen fuel from seawater: Hybrid material converts more sunlight and can weather seawater's harsh conditions October 4th, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

Quantum Dots/Rods

Quantum communications bend to our needs: By changing the wavelengths of entangled photons to those used in telecommunications, researchers see quantum technology take a major leap forward September 28th, 2017

Band Gaps, Made to Order: Engineers create atomically thin superlattice materials with precision September 26th, 2017

New approach on research and design for CQD catalysts in World Scientific NANO August 2nd, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

Photonics/Optics/Lasers

A step closer to understanding quantum mechanics: Swansea Universityís physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

MIPT scientists revisit optical constants of ultrathin gold films October 20th, 2017

Solar/Photovoltaic

New nanomaterial can extract hydrogen fuel from seawater: Hybrid material converts more sunlight and can weather seawater's harsh conditions October 4th, 2017

Researchers set time limit for ultrafast perovskite solar cells September 22nd, 2017

Copper catalyst yields high efficiency CO2-to-fuels conversion: Berkeley Lab scientists discover critical role of nanoparticle transformation September 20th, 2017

Solar-to-fuel system recycles CO2 to make ethanol and ethylene: Berkeley Lab advance is first demonstration of efficient, light-powered production of fuel via artificial photosynthesis September 19th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project