Tag Archives: nanocrystal

Nanocrystals Not Small Enough to Avoid Defects

Berkeley Lab Scientists at Advanced Light Source Show Dislocations Can Be Induced by Pressure in Ultrafine Nanocrystals

Nanocrystals as protective coatings for advanced gas turbine and jet engines are receiving a lot of attention for their many advantageous mechanical properties, including their resistance to stress. However, contrary to computer simulations, the tiny size of nanocrystals apparently does not safeguard them from defects.

In a study by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab)and collaborators from multiple institutions, nanocrystals of nickel subjected to high pressure continued to suffer dislocation-mediated plastic deformation even when the crystals were only three nanometers in size. These experimental findings, which were carried out at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-rays and ultraviolet light for scientific research, show that dislocations can form in the finest of nanocrystals when stress is applied. (more…)

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Brighter, Smaller Probes to Uncover the Secret Lives of Proteins

Berkeley Lab scientists create nanoparticle probes that may lead to a better understanding of diseases

Imagine tracking a deer through a forest by clipping a radio transmitter to its ear and monitoring the deer’s location remotely. Now imagine that transmitter is the size of a house, and you understand the problem researchers may encounter when they try to use nanoparticles to track proteins in live cells.

Understanding how a protein moves around a cell helps researchers understand the protein’s function and the cellular mechanisms for making and processing proteins. This information also helps researchers study disease, which at a cellular level may mean that a protein is malfunctioning, stops being made, or is sent to the wrong part of the cell. But nanoparticle probes that are too big can disrupt a protein’s normal activities. (more…)

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First Atomic-Scale Real-Time Movies of Platinum Nanocrystal Growth in Liquids

Berkeley Scientists Create Graphene Liquid Cells for Electron Microscopy Studies of Nanocrystal Formation

They won’t be coming soon to a multiplex near you, but movies showing the growth of platinum nanocrystals at the atomic-scale in real-time have blockbuster potential. A team of scientists with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley has developed a technique for encapsulating liquids of nanocrystals between layers of graphene so that chemical reactions in the liquids can be imaged with an electron microscope. With this technique, movies can be made that provide unprecedented direct observations of physical, chemical and biological phenomena that take place in liquids on the nanometer scale. (more…)

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Self-Assembling Nanorods: Berkeley Lab Researchers Obtain 1, 2 and 3D Nanorod Arrays and Networks

A relatively fast, easy and inexpensive technique for inducing nanorods – rod-shaped semiconductor nanocrystals – to self-assemble into one-, two- and even three-dimensional macroscopic structures has been developed by a team of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). This technique should enable more effective use of nanorods in solar cells, magnetic storage devices and sensors. It should also help boost the electrical and mechanical properties of nanorod-polymer composites.

Leading this project was Ting Xu, a polymer scientist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and the University of California (UC) Berkeley’s Departments of Materials Sciences and Engineering, and Chemistry. Xu and her research group used block copolymers – long sequences or “blocks” of one type of monomer bound to blocks of another type of monomer – as a platform to guide the self-assembly of nanorods into complex structures and hierarchical patterns. Block copolymers have an innate ability to self-assemble into well-defined arrays of nano-sized structures over macroscopic distances. (more…)

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Nanocrystals Go Bare: Berkeley Lab Researchers Strip Material’s Tiny Tethers

Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a universal technique for stripping nanocrystals of tether-like molecules that until now have posed as obstacles for their integration into devices. These findings could provide scientists with a clean slate for developing new nanocrystal-based technologies for energy storage, photovoltaics, smart windows, solar fuels and light-emitting diodes.

Nanocrystals are typically prepared in a chemical solution using stringy molecules called ligands chemically tethered to their surface. These hydrocarbon-based or organometallic molecules help stabilize the nanocrystal, but also form an undesirable insulating shell around the structure. Efficient and clean removal of these surface ligands is challenging and has eluded researchers for decades. (more…)

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