An Insight into the Phase Transformation of WS2 upon Fluorination

Sruthi Radhakrishnan; Deya Das; Liangzi Deng; Parambath M Sudeep; Guillaume Colas; Carlos A de Los Reyes; Sadegh Yazdi; Ching Wu Chu; Angel A Martí; Chandra Sekhar Tiwary; Tobin Filleter; Abhishek K Singh; Pulickel M Ajayan

doi:10.1002/adma.201803366

An Insight into the Phase Transformation of WS₂ upon Fluorination

Adv Mater. 2018 Nov;30(44):e1803366. doi: 10.1002/adma.201803366. Epub 2018 Sep 21.

Authors

Affiliations

¹ Department of Materials Science and NanoEngineering, Rice University, Houston, TX, 77005, USA.
² Materials Research Center, Indian Institute of Science, Bangalore, 560012, India.
³ Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, TX, 77004, USA.
⁴ Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, M5S3G8, Canada.
⁵ Department of Chemistry, Rice University, Houston, TX, 77005, USA.
⁶ Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, 80309, USA.
⁷ Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA.
⁸ Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, West Bengal, 721302, India.

PMID: 30239044
DOI: 10.1002/adma.201803366

Abstract

The transformation from semiconducting to metallic phase, accompanied by a structural transition in 2D transition metal dichalcogenides has attracted the attention of the researchers worldwide. The unconventional structural transformation of fluorinated WS₂ (FWS₂ ) into the 1T phase is described. The energy difference between the two phases debugs this transition, as fluorination enhances the stability of 1T FWS₂ and makes it energetically favorable at higher F concentration. Investigation of the electronic and optical nature of FWS₂ is supplemented by possible band structures and bandgap calculations. Magnetic centers in the 1T phase appear in FWS₂ possibly due to the introduction of defect sites. A direct consequence of the phase transition and associated increase in interlayer spacing is a change in friction behavior. Friction force microscopy is used to determine this effect of functionalization accompanied phase transformation.

Keywords: 2D magnetism; DFT calculations; TMDs; fluorination; phase transformation.

Abstract

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