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EXAMINING THE SURFACE CHEMISTRY AND BEHAVIOR OF COLLOIDALLY-SYNTHESIZED VANADIUM DIOXIDE
Restricted (Penn State Only)
Master of Science
Date of Defense:
October 30, 2018
Raymond Edward Schaak, Thesis Advisor
Thomas E Mallouk, Committee Member
Since its discovery in the 1960’s, vanadium dioxide (VO2) has been an invaluable compound in research and industry. Due to its unique insulator-metal transition that occurs near room temperature, and its ability to transmit or reflect infrared wavelengths depending on the crystal phase, VO2 has many possible applications, varying from medical and industrial to military and defense use. One example of an application for VO2 is its use in metamaterials, which can be designed to manipulate waves of light and sound at the sub-wavelength scale to yield properties not found in nature. Through the use of VO2, these materials are able to have a tunable response by transmitting or reflecting infrared light, which can be activated by various methods, such as mechanical strain, current, heat, or an applied voltage. As these metamaterials must be carefully designed and are oftentimes in the nanometer size scale, traditional methods of synthesis, such as chemical vapor deposition and solvothermal synthesis, often do not offer enough control over the size and dispersity of the resulting VO2 nanoparticles. Instead, colloidal synthesis of VO2 results in sub-10 nm particles that are relatively monodisperse. However, the colloidal synthesis of VO2 has not been studied nearly as much as the other synthesis methods. In the research reported herein, VO2 nanoparticles were colloidally synthesized and characterized, and used in subsequent experiments that involved examining the surface chemistry of the VO2 to silica coat the particles and form electrostatically-stabilized thin films on metadevice substrates. My research suggests that the colloidally-synthesized VO2 does not have the same properties as VO2 synthesized by chemical vapor deposition or solvothermal methods.
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