Nanoscale optical heating for the generation of high entropy nanomaterials

Abstract

From the high-purity silicon that is the foundation of computers to the organic semiconductors that capture energy in solar cells, our modern and future lifestyles are dependent on advanced and emerging materials. One class of materials that has long served humanity are alloys – formed by the random arrangement of multiple elements. Beginning with the bronze (copper + tin) tools used in early civilizations, through massive beams of steel (carbon + iron) that are pillars of our modern world, and leading to a still emerging diverse class of nanoscale catalysts that, for example, turn oil into plastics and new pharmaceuticals, new alloys are strongly associated with new capabilities. A nascent, yet promising class of nanoscale alloys is known as high entropy alloys. These alloys seek to create new materials properties and behaviors by combining five or more elements together in a random arrangement in a crystal with nanometer-scale dimensions. The large number of possible arrangements of these different atoms produces what is known as a high-entropy state. At present, only a few types of nanoscale high entropy alloys have been made, but they have shown great promise as catalysts for reactions that are poised to transform many application areas. The main scientific challenge that has hindered the widespread synthesis of these nanoscale high entropy alloys is actually quite simple: it is challenging to find five metallic elements that will combine in a single alloy material! One way to force the combination is high heat. What is needed is a new way to heat nanoscale materials to 1000 ºC so that alloys form, and then return them to room temperature fast enough to trap the alloy before its elements separate. This collaboration does just this by combining the expertise of two researchers from distinct fields. Benjamin Lear, Ph.D., is an expert in photothermal heating of nanoscale materials, and routinely runs chemical reactions under conditions that could work for this proposal. Raymond Schaak, Ph.D., is a world leader in the chemical synthesis of compositionally complex materials including alloys. Neither researcher alone has the capabilities needed to achieve nanoscale high entropy alloys. Combined, however, they have the expertise needed to establish a fundamentally new approach to materials. This project will position them as leaders in an emerging field of research and establish a new research direction for both laboratories in an area that is rapidly expanding and seeing increased attention from external funding agencies.

 

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