John Kieffer


2018 HH Dow

T: (734) 763-2595








Specific glass classes, like the chalcogenides, are interesting because of their practical application to applications that can take advantage of nonlinear optics, such as optical waveguides. To better understand and manipulate these properties it is necessary to investigate their origins, which is related to the atoms and molecules but also to the very structure of these materials. With the myriad of glasses that can be formed, one of the primary challenges in working with amorphous materials is simply picking the right glass for the right application. While the properties of these glasses are readily observed, it is less obvious how the structure of these glasses is related to these properties. Continuum random network (CRN) theories offer much insight into the formation and behavior of glasses, but the abundance of modified CRN theories, seems to suggest that there is more to the properties of these materials than a random network.
We are exploring the evolution of structures in glassy materials by exploring the connectivity between the molecules using Raman and Brillouin inelastic light scattering. Brillouin light scattering allows for high frequency phonons to be probed, which can in turn yield information about the complex modulus and viscoelastic properties of the sample. We will be producing amorphous materials via sol gel synthesis in order to fully control the stoichiometry and formation of the glasses we study. By using an array of techniques to more completely characterize these glasses, fundamental questions can be investigated. Does polyamorphism play a role in determining the properties of glassy materials? What are the exact mechanisms of glass formation, and how do they change in different environments? The possibilities for novel materials in the optoelectronics field make these very interesting science questions into valuable engineering problems.