Adam James Ellison

Viscosity of glass-forming liquids

The low-temperature dynamics of ultraviscous liquids hold the key to understanding the nature of glass transition and relaxation phenomena, including the potential existence of an ideal thermodynamic glass transition. Unfortunately, existing viscosity models, such as the Vogel–Fulcher–Tammann (VFT) and Avramov–Milchev (AM) equations, exhibit systematic error when extrapolating to low temperatures. We present a model offering an improved description of the viscosity–temperature relationship for both inorganic and organic liquids using the same number of parameters as VFT and AM. The model has a clear physical foundation based on the temperature dependence of configurational entropy, and it offers an accurate prediction of low-temperature isokoms without any singularity at finite temperature. Our results cast doubt on the existence of a Kauzmann entropy catastrophe and associated ideal glass transition.

Communication: Resolving the vibrational and configurational contributions to thermal expansion in isobaric glass-forming systems

A fundamental understanding of isobaric thermal expansion behavior is critical in all areas of glass science and technology. Current models of glass transition and relaxation behavior implicitly assume that the thermal expansion coefficient of glass-forming systems can be expressed as a sum of vibrational and configurational contributions. However, this assumption is made without rigorous theoretical or experimental justification. Here we present a detailed statistical mechanical analysis resolving the vibrational and configurational contributions to isobaric thermal expansion and show experimental proof of the separability of thermal expansion into vibrational and configurational components for Corning Jade glass.

Extending the L-band to 1620 nm using MCS fiber

Compositional modifications to the base MCS (antimony silicate) glass composition permit extension of useable L-band gain from 1615 to 1620 nm. This is achieved by shifting the signal excited state absorption band to longer wavelengths.

Photoelastic response of alkaline earth aluminosilicate glasses

Understanding the structural origins of the photoelastic response in oxide glasses is important for discovering new families of zero-stress optic glasses and for developing a predictive physical model. In this Letter, we have investigated the composition dependence of the stress optic coefficient C of 32 sodium aluminosilicate glasses with different types of alkaline earth oxides (MgO, CaO, SrO, and BaO). We find that most of the composition dependence of the stress optic response can be captured by a linear regression model and that the individual contributions from the alkaline earths to C depend on the alkaline earth-oxygen bond metallicity. High bond metallicity is required to allow bonds to be distorted along both the bonding direction and perpendicular to it. These findings are valuable for understanding the photoelastic response of oxide glasses.

Electrical properties of new glasses based on the Li2S–SiS2 system

Abstract Improvement of large energy density systems such as lithium ion batteries requires an understanding of the electrode materials and identification of new electrolytes. For safety reasons, solid sate electrolytes are preferred. This study is based on past results on the Li2S–SiS2 system. AC impedance spectroscopy was used to determine the ionic conductivity of glasses where additions were made of sulfides and oxides of groups IVA, VA, VB or VIA to the base glass composition 60/40 Li2S–SiS2 (mol%). These additions improved the stability of these glasses, so much so that thick samples (>2 mm ) could be prepared by cooling without quenching. Addition of lithium halides further increased conductivity. Ionic conductivities >2×10 −3 S / cm at room temperature were measured, amongst the largest reported in the glass literature for lithium electrolytes. The conductivity activation energy of these glasses will be reported.

69.2: Designing Strong Glass for Mobile Devices

Compared to plastic, glass is tougher, scratch resistant, offers optical quality and a richer look for consumer electronic applications. The mechanical performance of silicate glasses can be improved via ion-exchange in molten salts. Variables that affect the ion-exchange process, such as glass composition, thermal history, time, temperature, and bath chemistry will be discussed.

Investigation of surface mass transport in Al–Si–Ca–oxide glasses via the thermal induced decay of submicron surface gratings

In metal crystals, annealing induced decay of micron sized surface features occurs via surface rather than bulk diffusion. Surface transport also dominates the decay of micron sized patterns etched into semiconductors and initial stages in the sintering of ceramics. In oxide glasses, surface transport is expected to take over at a sufficiently small feature size as well, but this transition has not yet been identified, possibly because of the difficulties of preparing periodic gratings <10μm in glass surfaces with chemical etching. We therefore extended these investigations to submicron patterned glass surfaces using advanced lithography and dry etching to generate submicron sized patterns. The glasses selected have compositions along the center line of the SiO2–Al2O3–CaO phase diagram and hence are pseudobinaries, in which SiO4 units are increasingly replaced by AlCa0.5O4 units while maintaining the fourfold coordination of SiO2. The flow properties of these glasses can be studied at lower temperatures t...

New Materials for Optical Amplifiers

Publisher Summary Fiber plays an important role as an amplifying medium. The aluminum-doped silica is considered the only important commercial host and erbium the major amplifying dopant. It is observed that erbium is soluble in Al-silica and provides gain at the attenuation minimum for silica transmission fiber. An overview of materials used for optical amplification and a discussion on the application space and context for devices based on these materials are provided in the chapter. The chapter reviews the basic material properties required in glasses for the active devices and the materials and the methods by which these properties are drawn to fiber. Furthermore, the chapter illustrates the device applications. These applications relate principally to bandwidth extension and power scaling and include extended C-band, L-band, extended band Erbium–Doped Fiber Amplifiers (EDFAs), Thulium–Doped Fiber Amplifiers (TDFAs) operating in the S-band, and high-power 980 nm ytterbium fiber lasers for pumping the EDFAs. The common material systems explored include fluorides, alumina-doped silica, antimony-silicates, and tellurite.

Corning Incorporated: Designing a New Future with Glass and Optics

Corning Incorporated is a world leader in glass and ceramic products, and has been innovating in these materials since 1851. The company sells component-level technical products that are integrated into systems made by its customers. In most cases, those systems are significantly more efficient or in some instances fundamentally enabled by the performance of the Corning product. Corning calls its products “keystone components” for this reason. Keystone components often result from a combination of both material and process innovations, which tend to be difficult for other companies to duplicate. Developing keystone components requires patient investment in R&D (both materials and process) over long periods of time, and depends upon a culture of innovation and dedication to fundamental understanding. We highlight in this chapter three different keystone components developed by Corning in the past two decades—Corning® Gorilla® Glass for touch-enabled displays, Epic® sensors for drug discovery, and ClearCurve® optical fiber. In each case we provide an overview of Corning’s contributions to each field, describe the areas of technical challenge that still need to be addressed by the research community, and link those to the skills and capabilities that are needed to ensure further success in each.

Tm/sup 3+/ spectroscopy and amplifier performance of antimony silicate glasses

Summary form only given. Antimony silicates are surprisingly good hosts for Tm/sup 3+/ for 14 xx applications. Compositional dependencies of thulium spectroscopy and 14 xx emission lifetimes will be reviewed, and the performance of Tm-doped antimony silicate gain media will be discussed.