Millisecond Conversion of Metastable 2D Materials by Flash Joule Heating

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Controllable phase engineering is crucial for tailoring material properties.
• Synthesizing metastable materials, especially 2D ones, efficiently and affordably is challenging.

Purpose of the Study:

• To introduce flash Joule heating (FJH) as a method for rapid, bulk synthesis of metastable 1T phases of transition metal dichalcogenides (TMDs).
• To demonstrate tunable phase conversion in MoS2 and WS2.
• To investigate the underlying mechanisms of phase stabilization during FJH.

Main Methods:

• Utilized flash Joule heating (FJH) for rapid electrothermal treatment of MoS2 and WS2.
• Employed tungsten powder as a conductive additive to enhance conversion efficiency.
• Varied FJH conditions (duration, additives) to control the degree of phase conversion.
• Performed first-principles calculations to understand phase stabilization mechanisms.

Main Results:

• Achieved bulk conversion of MoS2 and WS2 from 2H to 1T phases in milliseconds using FJH.
• Reached up to 76% phase conversion for MoS2 with tungsten powder.
• Demonstrated tunable phase conversion by adjusting FJH parameters.
• Calculations confirmed vacancy formation and charge accumulation stabilize the 1T phase.

Conclusions:

• FJH provides rapid, scalable access to metastable 1T-phase TMDs.
• The method allows for the study of ratio-dependent properties.
• FJH is a promising technique for fundamental research and applications of metastable materials.