Nov 8 2018
Layered transition metal dichalcogenides (TMDCs), which are materials formed of metal nanolayers interposed between two other layers of chalcogens, have gained considerable attention from the research community owing to their potential to exfoliate into 2D single layers.
Like graphene, they retain some of the distinctive characteristics of the bulk material as well as exhibit exceptional electrocatalytic activity, direct-gap semiconducting behavior, and unique quantum phenomena such as charge density waves (CDW).
It is challenging to produce complex multi-principle element TMDCs vital development of new generations of electronic, quantum, and energy conversion materials in the future.
It is relatively simple to make a binary material from one type of metal and one type of chalcogen. Once you try to add more metals or chalcogens to the reactants, combining them into a uniform structure becomes challenging. It was even believed that alloying of two or more different binary TMDCs in one single-phase material is absolutely impossible.
Viktor Balema, Senior Scientist, Ames Laboratory.
In order to solve this problem, postdoctoral research associate Ihor Hlova applied ball-milling and subsequent reactive fusion to integrate TMDCs such as TaS2, MoS2, WSe2, NbSe2, and WS2. Ball-milling is a mechanochemical process that can exfoliate layered materials into single- or few-layer nanosheets with the ability to further restore their multi-layered arrangements by restacking.
“Mechanical processing treats binary TMDCs like shuffling together two separate decks of cards,” said Balema. “They are reordered to form 3D-heterostructured architectures—an unprecedented phenomenon first observed in our work.”
When the resulting 3D-heterostructures are heated, they are brought to the edge of their stability, atoms within and between their layers are reordered, leading to single-phase solids that can in turn be exfoliated, or peeled into 2D single layers analogous to graphene, but with their own, distinctive tunable properties.
Preliminary examination of properties of only a few, earlier unavailable compounds, proves as exciting as synthetic results are. Very likely, we have just opened doors to the entirely new class of finely tunable, quantum matter.
Vitalij Pecharsky, Senior Scientist and Distinguished Professor of Materials Science and Engineering, Ames Laboratory.
This study was supported by the Ames Laboratory’s Directed Research and Development program under contract with the U.S. Department of Energy.