Timothy Strobel subjects materials to high pressures to understand chemical processes and interactions and to create new, advanced energy-related materials.

    For instance, silicon is the second most abundant element in the Earth’s crust and a mainstay of the electronics industry. But normal silicon is not optimal for solar energy. In its conventional crystalline form, silicon is relatively inefficient at absorbing the wavelengths most prevalent in sunlight. Strobel made a discovery that may turn things around. Using the high-pressure techniques pioneered at Carnegie, he created a novel form of silicon with its atoms arranged in a cage-like structure. Unlike normal silicon, this new form has near-ideal properties for absorbing sunlight and could potentially usher in an entirely new generation of solar cells.

    Understanding the chemical reactions that can create tiny molecular cages that hold other “guest” molecules—structures called clathrates—is key to creating a new generation of electronic devices and possible energy materials. Strobel and his team were the first to use high-pressure synthesis to create a stable clathrate of sodium (Na) and silicon (Si)—the least understood system of the so-called group 14 clathrates. Strobel also created a new clathrate of hydrogen sulfide (H2S) and molecular hydrogen (H2). Both findings open the door for major advances in materials science.

    In addition to these experiments, Strobel and his team calculated how the materials would behave. Calculations and experiments revealed that sodium clathrates are thermodynamically stable at high pressure. The consistency suggests that scientists can use theoretical calculations to predict new synthesis routes for other compounds.

    In other work, a team including Strobel reported the synthesis of an ionic semiconductor —Mg2C—that is fully recoverable to ambient conditions. Semiconductors are substances with electrical conductivity between insulators and metals used in electronic circuits.


    Laboratory Instrumentation



    Recent Publications