Final Report Summary - DISORDER CONTROL (Tuning Disorder in Chalcogenides to realize Advanced Functional Devices)
The goal of this project was the realization of novel advanced functional materials via a tuning of the disorder in the corresponding solids. Indeed, within the framework of this project we realized that disorder tuning enables a significant impact on material properties, not just the thermal and electrical conductivities. In the course of this work we realized that the most pronounced impact of disorder occurs in a unique class of materials, which we have coined ‘incipient metals’. These materials are characterized by a novel, fundamental bonding mechanism, which we have called metavalent bonding. Metavalent bonding is a bonding mechanism besides the five textbook cases of metallic, ionic, covalent, hydrogen and van der Waals bonding. Yet, the key findings of this project go beyond establishing a novel bonding mechanism in solids and identifying the pronounced impact of disorder on the properties of materials which utilize this bonding mechanism. The map we have developed to describe bonding in solids does not only allow the separation of different bonding mechanisms. It also provides a novel approach to materials design and optimization, a finding of potentially high application relevance.