ANL Salary/Fringe Designer Glass Ceramics

The aim of this proposal is to develop novel glass ceramics based on a modified fluorozirconate (ZBLAN) glass composition. We term our proposed material a ‘designer’ glass ceramic because we will use pulsed laser deposition (PLD) to synthesize a layered nanocomposite glass ceramic in which we can control the distribution of the optically-active dopants and of the nanocrystalline phase that is responsible for the optical behavior that is observed. This method has not previously been explored, but we believe that by controlling the distribution of the nanocrystalline phase and its proximity to the optically-active dopant, we will be able to gain a greater understanding of the role that each component contributes to the novel optical behavior, and hence optimize this behavior for applications in wavelength shifters pertaining to up- and down-converters in solar cells. Specifically the investigators will: a) Synthesize samples of nanocomposite FCZ glasses doped with europium, using pulsed-laser deposition (PLD) b) Explore the optical properties of the nanocomposites both in the as-deposited state and following heat-treatment to induce crystallization and/or phase transformation of the BaCl2 c) Perform initial structure/property investigations via a series of systematic heat treatments, XRD, and Mössbauer spectroscopy. d) Perform compositional analysis using TEM and energy-dispersive X-ray (EDX) microanalysis and map the elemental distribution using energy-filtered TEM (EFTEM) in addition to exploring the electronic structure using electron energy loss spectroscopy (EELS). e) Perform optical property measurements using photoluminescence (PL), ellipsometry and optical spectrophotometry (OS) to assess the effect of changes in nanocomposite structure such as spacing of BaCl2 layers and separation between BaCl2 and the dopant. f) Prepare TEM samples via focused ion beam (FIB) lift-out and other established techniques and perform TEM structural and compositional studies of as-deposited and ex situ heat-treated material for correlation with optical properties. g) Perform in situ TEM and synchrotron XRD heating studies to follow the crystallization process and dopant diffusion. h) Explore the effects of introducing different optically active dopants such as Ho, Gd, Nd, Sm, Tb, Yb and Er.