Controlling the atomic structure and thermal conductivity of disordered SiO2 thin films using substrate surfaces
KIRCHNER K. 1,2, JEEM M. 2, OGASAWARA S. 2, OHTA H. 2, KOHARA S. 3, KOGANEZAWA T. 4, KUMARA R. 4, FUJIOKA M. 2, NISHI J. 2, MATSUO Y. 2, MAURO J. 1, ONO M. 2
1 The Pennsylvania State University, University Park, United States; 2 Hokkaido University, Sapporo, Japan; 3 National Institute for Materials Science (NIMS), Tsukuba, Japan; 4 Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, Japan
Understanding and controlling the mechanisms for structure-property-performance relationships in glass-forming systems is a constant challenge. For bulk silica glass, the criticality of topological fluctuations has been realized, and through pressure-quenching these topological fluctuations can be manipulated for advantageous property responses, such as for thermal conductivity. Instead of pressurizing, this work explores how topological fluctuations can be manipulated by changing the substrate crystal surface of thin films. Specifically, through the synthesis and characterization of thin film silica, we investigate the topochemical effect (i.e., how changing the chemical force of the substrate surface alters the atomic structure of the deposited film) to explore property effects of changing structural fluctuations. One such property of interest is thermal conductivity, where we show that thermal conductivity behavior is dependent on the substrate onto which the disordered SiO2 film was deposited. With this investigation, we characterize structural effects via Grazing Incidence X-ray Diffraction (GI-XRD) to explore how the surface chemistry affects the formation of the deposited film and the mechanisms driving previously unexplained structure-property-performance relationships in disordered SiO2 thin films.