Two-dimensional high entropy alloys and ceramics

Introduction

“Entropy engineering” recently had exceptional impact on bulk materials science by invention of bulk high entropy alloys and ceramics. The underlying idea is that by equiatomically adding ≥5 principal elements to alloys/compounds, the much increased configurational entropy stabilizes otherwise non-accessible single “high entropy” phases with a unique random elemental occupancy on a crystalline lattice and hence novel functional properties.

Impact of 2D Materials

Likewise, reducing dimensionality in “two-dimensional” (2D) materials recently had exceptional impact on materials science due to the 2D materials’ unique functional properties. Despite these exciting individual prospects of “entropy engineering” and “2D materials”, the combination of these two concepts to synergetically create novel 2D high entropy materials (2D HEMs) as a novel materials class with novel functional properties, with possible applications in electronics and catalysis, remains lacking.

Project Overview

In “HighEntropy2d”, we will:

1. Fabricate unprecedented 2D HEMs (2D high entropy alloys, oxides, and sulfides) using for the first time scalable vapor deposition.
2. Utilize a 2D template/2D confinement approach for both 2D film and 2D nanoflake form.
3. Assess their novel properties and perform first tests of their applicability for electronic devices and catalysis.

Research Opportunities

Reducing HEM dimensionality to 2D will also create a unique opportunity to, for the first time, study in situ and at the atomic scale currently unknown fundamental diffusion, crystallization, phase transition, and separation mechanisms in HEMs. This will be achieved using a globally unique (scanning) transmission electron microscopy ((S)TEM) setup, to obtain fundamental insights relevant to HEMs even beyond the here newly introduced 2D HEMs.

Expertise

The proven track record of principal applicant Bernhard C. Bayer in 2D materials synthesis and atomic scale in situ (S)TEM is an ideal basis for this ambitious research programme.