Chalcogenides by Design: Taming Bond No. 6

Datum

17.05.2019

Zeit

11:00 - 12:00

Sprecher

Prof. Dr. Matthias Wuttig

Zugehörigkeit

RWTH Aachen, I. Physikalisches Institut (IA)

Sprache

en

Hauptthema

Materialien

Host

Brit Präßler-Wüstling

Beschreibung

It has been a long-time dream of mankind to design materials with tailored properties. In recent years, the focus of our work has been the design of phase change materials for applications in data storage. In this application, a remarkable property portfolio of phase change materials (PCMs) is employed, which includes the ability to rapidly switch between the amorphous and crystalline state. Surprisingly, in PCMs both states differ significantly in their properties. This material combination makes them very attractive for data storage applications in rewriteable optical data storage, where the pronounced difference of optical properties between the amorphous and crystalline state is employed. This unconventional class of materials is also the basis of a storage concept to replace flash memory. This talk will discuss the unique material properties, which characterize phase change materials. In particular, it will be shown that only a well-defined group of materials utilizes a unique bonding mechanism (‘Bond No. 6’), which can explain many of the characteristic features of crystalline phase change materials. Different pieces of evidence for the existence of this novel bonding mechanism, which we have coined metavalent bonding, will be presented. This insight is subsequently employed to design phase change materials as well as thermoelectric materials. Yet, the discoveries presented here also force us to revisit the concept of chemical bonds and bring back a history of vivid scientific disputes about ‘the nature of the chemical bond’. M. Zhu, O. Cojocaru-Mirédin, A.M. Mio, J. Keutgen, M. Küpers, Y. Yu, J.Y. Cho, R. Dronskowski, and M. Wuttig, Unique bond breaking in crystalline phase change materials and the quest for metavalent bonding, Advanced Materials 30, 1706735 (2018) // M. Cagnoni, D. Führen and M. Wuttig, Thermoelectric performance of IV-VI compounds with octahedral-like coordination: a chemical-bonding perspective, Advanced Materials 30, 1801787 (2018) // M. Wuttig, V.L. Deringer, X. Gonze, C. Bichara, J.-Y. Raty, Incipient Metals: Functional Materials with a Unique Bonding Mechanism, Advanced Materials 30, 1803777 (2018) // J.-Y. Raty, M. Schumacher, P. Golub, V.L. Deringer, C. Gatti, M. Wuttig, A Quantum-Mechanical Map for Bonding and Properties in Solids, Advanced Materials 31, 1806280 (2019)

Links

• Seminars at the IFW

Letztmalig verändert: 24.06.2019, 15:23:35