Angle resolved vibrational properties of anisotropic transition metal trichalcogenide nanosheets

Wilson Kong, Cihan Bacaksiz, Bin Chen, Kedi Wu, Mark Blei, Xi Fan, Yuxia Shen, Hasan Sahin, David Wright, Deepa S. Narang, Sefaattin Tongay

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Layered transition metal trichalcogenides (TMTCs) are a new class of anisotropic two-dimensional materials that exhibit quasi-1D behavior. This property stems from their unique highly anisotropic crystal structure where vastly different material properties can be attained from different crystal directions. Here, we employ density functional theory predictions, atomic force microscopy, and angle-resolved Raman spectroscopy to investigate their fundamental vibrational properties which differ significantly from other 2D systems and to establish a method in identifying anisotropy direction of different types of TMTCs. We find that the intensity of certain Raman peaks of TiS3, ZrS3, and HfS3 have strong polarization dependence in such a way that intensity is at its maximum when the polarization direction is parallel to the anisotropic b-axis. This allows us to readily identify the Raman peaks that are representative of the vibrations along the b-axis direction. Interestingly, similar angle resolved studies on the novel TiNbS3 TMTC alloy reveal that determination of anisotropy/crystalline direction is rather difficult possibly due to loss of anisotropy by randomization distribution of quasi-1D MX6 chains by the presence of defects which are commonly found in 2D alloys and also due to the complex Raman tensor of TMTC alloys. Overall, the experimental and theoretical results establish non-destructive methods used to identify the direction of anisotropy in TMTCs and reveal their vibrational characteristics which are necessary to gain insight into potential applications that utilize direction dependent thermal response, optical polarization, and linear dichroism.

Original languageEnglish (US)
Pages (from-to)4175-4182
Number of pages8
Issue number12
StatePublished - Mar 28 2017

ASJC Scopus subject areas

  • General Materials Science


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