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Phase Transition across Anisotropic NbS 3 and Direct Gap Semiconductor TiS 3 at Nominal Titanium Alloying Limit
Author(s) -
Wu Kedi,
Blei Mark,
Chen Bin,
Liu Lei,
Cai Hui,
Brayfield Cassondra,
Wright David,
Zhuang Houlong,
Tongay Sefaattin
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202000018
Subject(s) - materials science , monoclinic crystal system , triclinic crystal system , raman spectroscopy , anisotropy , phase transition , van der waals force , phase (matter) , condensed matter physics , semiconductor , high resolution transmission electron microscopy , crystallography , nanotechnology , crystal structure , transmission electron microscopy , optics , optoelectronics , chemistry , physics , organic chemistry , molecule
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 ) Ti x S 3 alloys is demonstrated for the first time. Results show that Nb (1− x ) Ti x S 3 can be fully alloyed across the entire composition range from triclinic‐phase NbS 3 to monoclinic‐phase TiS 3 . Surprisingly, incorporation of a small concentration of Ti ( x ≈ 0.05–0.18) into NbS 3 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 ) Ti x S 3 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.