Growth and Raman Scattering Investigation of a New 2D MOX Material: YbOCl

Abstract

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1903017 (1 of 10) MOX (M = Fe, Co, Mn, Cr, Lanthanide, or Actinide metals; O = oxygen, X = F, Cl, Br, I), an emerging type of 2D layered materials, have been theoretically predicted to possess unique electronic and magnetic properties. However, 2D MOX have rarely been investigated. Herein, for the first time, ultrathin high-quality ytterbium oxychloride (YbOCl) single crystals are successfully synthesized via an atmospheric pressure chemical vapor deposition method. Both theoretical simulations and experimental measurements are utilized to systematically investigate the Raman properties of 2D YbOCl nanosheets. The experimentally observed Eg mode at 85.53 cm−1 and A1g mode at 138.17 cm−1 demonstrate a good match to the results from density functional theory calculations. Furthermore, the temperature-dependent and thicknessdependent Raman scattering spectra reveal the adjacent layers in YbOCl nanosheets show a relatively weak van der Waals interaction. Additionally, the polarized-dependent Raman scattering spectra show the intensity of A1g mode exhibits twofold patterns while the intensity of the Eg mode remains constant as the rotation angle changes. These findings could provide the first-hand experimental information about the 2D YbOCl crystals. metal dichalcogenides (TMDs),[10–12] and other few star materials.[13,14] However, these star materials still face great challenges in relatively low electronic performance, instability, and inefficient production, which limit their practical applications in the future. Recently, the 2D layered oxygenated compounds with fantastic properties have also stirred up research interests. For example, 2D Bi2O2Se crystal owns excellent performance, including high Hall mobility, high-performance flexibility, and high air stability, signifying its great potential in the applications of ultrafast, flexible optoelectronic devices.[15–17] Being a striking family member of 2D layered materials, MOX (M = Fe, Co, Mn, Cr, Lanthanide, or Actinide metals; O = oxygen, X = F, Cl, Br, I) have been theoretically predicted to own intriguing electronic and magnetic properties.[5] For instance, monolayer chromium oxyhalide (CrOX; X = Cl or Br) have been identified as intrinsic ferromagnetic semiconductors with Curie temperatures of up to 160 and 129 K, respectively, making 2D CrOX an excellent platform for fundamental magnetic investigation and future spintronic applications.[18] BiOCl nanosheets/TiO2 nanotube arrays heterojunction with ultrahigh on/off ratio and remarkable detectivity, can be used as high-performance UV photodetector.[19] However, so far the synthesis, properties, and applications of MOX have been rarely experimentally studied. Growth and Raman Scattering Investigation of a New 2D MOX Material: YbOCl