Phase Transition across Anisotropic NbS3 and Direct Gap Semiconductor TiS3 at Nominal Titanium Alloying Limit

Kedi Wu*, Mark Blei, Bin Chen, Lei Liu, Hui Cai, Cassondra Brayfield, David Wright, Houlong Zhuang, Sefaattin Tongay

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Alloying selected layered transitional metal trichalcogenides (TMTCs) with unique chain-like structures offers the opportunities for structural, optical, and electrical engineering thus expands the regime of this class of pseudo-one-dimensional materials. Here, the novel phase transition in anisotropic Nb(1− x )TixS3 alloys is demonstrated for the first time. Results show that Nb(1− x )TixS3 can be fully alloyed across the entire composition range from triclinic-phase NbS3 to monoclinic-phase TiS3. Surprisingly, incorporation of a small concentration of Ti (x ≈ 0.05–0.18) into NbS3 host matrix is sufficient to induce triclinic to monoclinic transition. Theoretical studies suggest that Ti atoms effectively introduce hole doping, thus rapidly decreases the total energy of monoclinic phase and induces the phase transition. When alloyed, crystalline and optical anisotropy are largely preserved as evidenced by high resolution transmission electron microscopy and angle-resolved Raman spectroscopy. Further Raman measurements identify Raman modes to determine crystalline anisotropy direction and offer insights into the degree of anisotropy. Overall results introduce Nb(1− x )TixS3 as a new and easy phase change material and mark the first phase engineering in anisotropic van der Waals (vdW) trichalcogenide systems for their potential applications in two-dimensional superconductivity, electronics, photonics, and information technologies.

Original languageEnglish (US)
Article number2000018
JournalAdvanced Materials
Issue number17
StatePublished - Apr 1 2020


  • 2D materials
  • alloys
  • crystal growth
  • material synthesis
  • quantum materials

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • General Materials Science


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