Chemical bonding and Born charge in 1T-HfS2

Sabine N. Neal, Shutong Li, Turan Birol, Janice L. Musfeldt

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Abstract

We combine infrared absorption and Raman scattering spectroscopies to explore the properties of the heavy transition metal dichalcogenide 1T-HfS 2. We employ the LO–TO splitting of the E u vibrational mode along with a reevaluation of mode mass, unit cell volume, and dielectric constant to reveal the Born effective charge. We find ZB* = 5.3e, in excellent agreement with complementary first-principles calculations. In addition to resolving the controversy over the nature of chemical bonding in this system, we decompose Born charge into polarizability and local charge. We find α = 5.07 Å 3 and Z * = 5.2e, respectively. Polar displacement-induced charge transfer from sulfur p to hafnium d is responsible for the enhanced Born charge compared to the nominal 4+ in hafnium. 1T-HfS 2 is thus an ionic crystal with strong and dynamic covalent effects. Taken together, our work places the vibrational properties of 1T-HfS 2 on a firm foundation and opens the door to understanding the properties of tubes and sheets.

Original languageEnglish (US)
Article number45
Journalnpj 2D Materials and Applications
Volume5
Issue number1
DOIs
StatePublished - Apr 2021

Bibliographical note

Funding Information:
Research at the University of Tennessee is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science Division under award DE-FG02-01ER45885. The work at the University of Minnesota is supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-2011401. We acknowledge the Minnesota Supercomputing Institute (MSI) at the University of Minnesota for providing resources that contributed to the research results reported within this paper. We thank S. Najmaei and I. Boulares at the U. S. Army Research Lab for the 1T-HfS2 crystal and useful conversations.

Publisher Copyright:
© 2021, The Author(s).

Keywords

  • cond-mat.mtrl-sci

MRSEC Support

  • Partial

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