02-09-18
Professor Julia Greer and graduate student Andrey Vyatskikh have created complex nanoscale metal structures using 3-D printing. The process, once scaled up, could be used in a wide variety of applications and opens the door to the creation of a new class of materials with unusual properties that are based on their internal structure. [Caltech story]
Tags: research highlights MedE MCE Julia Greer MatSci Andrey Vyatskikh
11-20-17
Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and his colleagues’ semiconductor research has shown that the coupling between electrons and thermal vibrations may be sapping energy from Light-emitting diodes—or LEDs. "Our work shows for the first time that the ever-present interaction between electrons with lattice vibrations can, by itself, explain why excited electrons can leak out of the active layer and account for inefficiencies in GaN LEDs," Professor Bernardi says. [Caltech story]
10-10-17
Brent Fultz, Barbara and Stanley R. Rawn, Jr., Professor of Materials Science and Applied Physics, and colleagues have pinpointed that arrangement of atoms is the main source of an increase in entropy during the glass transition. One persistent mystery about metallic glasses occurs at the so-called "glass transition." A cold metallic glass is hard and brittle, but when it is heated past a certain point—the glass transition—it becomes soft. [Caltech story]
07-13-17
Andrei Faraon, Assistant Professor of Applied Physics and Materials Science, and colleagues have discovered how to use computer-chip manufacturing technologies to create the kind of reflective materials that make safety vests, running shoes, and road signs appear shiny in the dark. The new technology uses surfaces covered by a metamaterial consisting of millions of silicon pillars, each only a few hundred nanometers tall. By adjusting the size of the pillars and the spacing between them, Faraon can manipulate how the surface reflects, refracts, or transmits light. [Caltech story]
07-13-17
Xiaoyue Ni, a materials science graduate student working with Professor Julia Greer, has shown that metals undergo permanent deformation even prior to yielding—the threshold at which a material under strain becomes permanently deformed. "What Xiaoyue's data are showing is that from the first moment you start deforming it, the dislocations start being active," Greer says. Now that we know how to do this, we can probe a variety of different classes of materials. [Caltech story]
06-28-17
Harry Atwater, Howard Hughes Professor of Applied Physics and Materials Science; Director, Joint Center for Artificial Photosynthesis, and colleagues have combined nanophotonics and thermoelectrics to generate materials capable of distinguishing between tiny differences in wavelengths of light. [Caltech story]
06-21-17
Professor Andrei Faraon, graduate student Ehsan Arbabi, and their colleagues have developed a metasurface or a sheet of material that can be altered on demand to exhibit properties not usually found in natural materials. For example, materials engineered at the nanoscale can control the dispersion of light and could be the basis of next-generation spectrometers and other imaging devices. [Caltech story]
06-20-17
Senior Daniel Lim has received the 2017 Library Friends' Senior Thesis Prize for his work on sculpting nanofilms with laser illumination. Lim's thesis, titled "Revolution in large-area curved surface lithography: Nanofilm sculpting by thermocapillary modulation," is based on experimental research he conducted over two years in the laboratory of Professor of Applied Physics, Aeronautics, and Mechanical Engineering Sandra M. Troian. "Our group has been working on thermocapillary sculpting of nanofilms for several years now,” says Troian. "Daniel advanced this concept by demonstrating an inverse projection method, which imbues the sculpting process with far greater versatility. Daniel is an exceptional student—a rare combination of superb talent, tremendous drive, utmost professionalism, and entrepreneurial chops. " [Caltech story]
Tags: APhMS honors research highlights MCE Sandra Troian Daniel Lim
06-15-17
For the first time, Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and colleagues have been able to directly observe the ultrafast motion of electrons immediately after they are excited with a laser—and found that these electrons diffuse into their surroundings much faster and farther than previously expected. "Our work shows the existence of a fast transient that lasts for a few hundred picoseconds, during which electrons move much faster than their room-temperature speed, implying that they can cover longer distances in a given time when manipulated with lasers," says Professor Bernardi. "This non-equilibrium behavior could be employed in novel electronic, optoelectronic, and renewable energy devices, as well as to uncover new fundamental physics." [Caltech story]
04-06-17
Paul M. Bellan, Professor of Applied Physics , and colleagues have discovered a new way to determine the wavelength of energy flowing through plasma in space—a method that was recently applied during a NASA mission that yielded the first solid evidence of how energy sloshes back and forth in a magnetic wave that moves through the plasma surrounding the earth. [Caltech story]
