GOMD 2020 Award lecture abstracts
Stookey Lecture of Discovery
Antoni Tomsia; Lawrence Berkeley Lab, USA
George W. Morey award
Glass: We love it, but it breaks
Walter Kob; University of Montpellier, France
Glasses have many outstanding properties that are exploited in a multitude of applications. Sadly, glasses have the flaw that they break, often in a catastrophic manner, thus preventing us to use them in certain applications. The fact that on the microscopic level glasses are disordered is not a good reason for them to be fragile since the bonding between the atoms is strong. This leaves the hope that the strength of glasses can be improved by considering special compositions and a clever manufacturing process for the glass. A further step in the direction of stronger glasses is to obtain a better understanding of the fracture process on the microscopic level. In this talk I will therefore present some recent results of large-scale computer simulations of sodium-silicate glasses in which we investigated how the fracture process depends on composition, temperature and other relevant parameters. The insight gained from these simulations should help to improve in the future the mechanical behavior of real glasses.
Norbert J. Kreidl Award for Young Scholars
Reconfigurable materials and optics: A phase change for the better
Yifei Zhang, Massachusetts Institute of Technology, USA
Optical phase change materials (O-PCMs), a unique group of materials featuring drastic optical property contrast upon solid-state phase transition, have found widespread adoption in photonic switches, reconfigurable meta-optics, reflective display, and optical neuromorphic computers. Current phase change materials, such as Ge-Sb-Te (GST), exhibit large contrast of both refractive index (Δn) and optical loss (Δk), simultaneously. The coupling of both optical properties fundamentally limits the function and performance of many potential applications. We report a new class of O-PCMs, Ge-Sb-Se-Te (GSST) which breaks this traditional coupling. The compositionally optimized alloy Ge2Sb2Se4Te1 claims an unprecedented material figure of merit over two orders of magnitude larger than that of classical GST alloys, benefiting from blue-shifted interband transitions as well as minimal free carrier absorptions, as confirmed by Hall measurements. In-situ heating TEM and XRD measurements are carried out to confirm and understand the crystal structures of Ge2Sb2Se4Te1. We show that Ge2Sb2Se4Te1, combining its broadband low loss (1 – 18.5 μm), large optical contrast (Δn = 2.0), and significantly improved glass forming ability, enables an entirely new family of integrated and free-space nonvolatile devices with unprecedented high performances.
Varshneya Glass Science lecture abstract:
Mechanical properties and thermal behavior of hydrous glasses
Professor Joachim Deubener, Clausthal University of Technology, Germany
The lecture focuses on the impact of hydration on the mechanical properties and the thermal behavior of various oxide glasses including silicate, borosilicate and borate compositions. Glasses with a total water content up to 20 mol% H2O were prepared under wet condition of melting using an external pressure of 5 kbar. Firstly, an insight into their structure and related water speciation will be given, followed by an analysis on water-induced changes in viscosity and sub-Tg relaxation. The central approach of studying mechanical properties of hydrous glasses is to trigger a situation of having water species (hydroxyl groups and water molecules) already dissolved in the glass structure and to confront them with environmental water molecules reacting at their surfaces. Thus, the contributions of dissolved water and humidity on elastic constants, hardness, crack formation and propagation will be highlighted in the central part of the lecture by reviewing mechanical tests that were conducted in vacuum, dry nitrogen gas and ambient air.
Varshneya Glass Technology lecture
Idea to innovation of optical fibers
Professor Younes Messaddeq, University of Laval, Canada
The main issues and greatest challenges in developing new generation of optical fibers span a wide variety of aspects: from glass synthesis and purification to the shaping and integration of fibers into photonic devices. Nowadays, although glass science is still rooted in the discovery and exploration of unknown properties, new drivers have emerged for the study and development of innovative technologies. In this talk, we will examine how different novel optical fibers based on silica and heavy oxide glasses are being developed. Using pioneering concepts that are based on transverse and longitudinal structures at the nanometric level, we uncover new properties supporting promising applications with potential impact in diverse areas such as information technology, environmental monitoring, and biomedical devices, to name a few.
Examples in selected application fields will illustrate advances in optical fiber design. For communication, multicore doped silica fibers act as fiber amplifiers for high capacity transmission, while multi-material fibers are enabling wireless networks operating at 2.4 GHz with excellent signal quality. For medicine, multi-functional fibers can transmit both light and electricity for probing neural activity in vivo. Fibers featuring these two functions are usually composed either of a single material that supports the different properties, or of a combination of different materials.
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