December 2020
Season's Greetings
Happy Holidays from everyone at the MIT Materials Research Laboratory. We hope your holidays are filled with health, joy and laughter throughout the New Year.
Researchers find a better way to
design metal alloys
Researchers have found a new way to predict the properties of metal alloys based on reactions at the boundaries between the crystalline grains of the primary metal. In this image, the colored dots indicate the likelihood that atoms will collect along these boundaries rather than penetrating through.
Advanced metal alloys are essential in key parts of modern life, from cars to satellites, from construction materials to electronics. But creating new alloys for specific uses, with optimized strength, hardness, corrosion resistance, conductivity, and so on, has been limited by researchers’ fuzzy understanding of what happens at the boundaries between the tiny crystalline grains that make up most metals.

Credits: Image courtesy of the researchers
Discovery suggests new promise for nonsilicon computer transistors
MIT researchers have found that an alloy material called InGaAs could be suitable for high-performance computer transistors. If operated at high-frequencies, InGaAs transistors could one day rival silicon. This image shows a solid state memory wafer traditionally made of silicon.
For decades, one material has so dominated the production of computer chips and transistors that the tech capital of the world — Silicon Valley — bears its name. But silicon’s reign may not last forever.

MIT researchers have found that an alloy called InGaAs (indium gallium arsenide) could hold the potential for smaller and more energy efficient transistors. Previously, researchers thought that the performance of InGaAs transistors deteriorated at small scales. But the new study shows this apparent deterioration is not an intrinsic property of the material itself.
A cool advance in thermoelectric conversion
In a topological Weyl semimetal, the electronic properties are controlled by Weyl fermions, which do not possess any mass and to some extent resemble photons. When an external magnetic field is applied, these Weyl fermions are able to convert waste heat into electricity extremely effectively and efficiently. Credits:
Image courtesy of researchers.
More than two-thirds of the energy used worldwide is ultimately ejected as “waste heat.” Within that reservoir of discarded energy lies a great and largely untapped opportunity. As reported in a recent issue of Nature Communications, the Nuclear Science & Engineering, Quantum Matter Group — has achieved a breakthrough in thermoelectric generation, which offers a direct means of converting thermal energy, including waste heat, into electricity.
An LED that can be integrated directly
into computer chips
MIT researchers have developed a bright, efficient silicon LED, pictured, that can be integrated directly onto computer chips. The advance could reduce cost and improve performance of microelectronics that use LEDs for sensing or communication. Credits: Courtesy of the researchers
Light-emitting diodes — LEDs — can do way more than illuminate your living room. These light sources are useful microelectronics too.

Smartphones, for example, can use an LED proximity sensor to determine if you’re holding the phone next to your face (in which case the screen turns off). The LED sends a pulse of light toward your face, and a timer in the phone measures how long it takes that light to reflect back to the phone, a proxy for how close the phone is to your face. LEDs are also handy for distance measurement in autofocus cameras and gesture recognition.
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