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Recent research has demonstrated the potential for topological superconductivity, anisotropic Majorana bound states, optical nonlinearity, and enhanced electrochemical activity for transition metal dichalcogenides (TMDs) with a 2M structure. These unique TMD compounds exhibit metastability and, upon heating, undergo a transition to the thermodynamically stable 2H phase. The 2M phase is commonly made at high temperatures using traditional solid-state methods, and this metastability further complicates the growth of large 2M WS2 crystals. Herein, a novel synthetic method was developed, focusing on a molten salt reaction to synthesize large 2H crystals and then inducing transformation to the 2M phase through intercalation and thermal treatment. The 2H crystals were intercalated via a room-temperature sodium naphthalenide solution, producing a previously unreported Na-intercalated 2H WS2 phase. Thermal heating was required to facilitate the phase transition to the intercalated 2M crystal structure. This phase transition was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), electron dispersive X-ray spectroscopy (EDS), and Raman spectroscopy, which confirmed the synthesis of the intercalated 2M phase. Upon deintercalation, crystal and powder samples showed superconductivity with a Tc of 8.6–8.7 K, similar to previously reported values. The generality of this process was further demonstrated using alkali metal triethyl borohydride to intercalate 2H WS2 and produced the desired 2M phase. This novel synthetic method has broad implications for discovering metastable phases in other TMD families and layered materials. Separation of the intercalation and phase transition also has the potential to allow for large-scale synthesis of this technologically important phase with greater control over each step of the reaction.
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Poly (3‐hexylthiophene) (P3HT) Crystalsomes: Tiling 1D Polymer Crystals on a Spherical Surface
Abstract Polymer crystalsomes are a class of hollow crystalline polymer nanoparticles with shells formed by single crystals with broken translational symmetry. They have shown intriguing mechanical, thermal, and biomedical properties associated with spherical packing. Previously reported crystalsomes are formed by quasi‐2D lamellae which can readily tile on a spherical surface. In this work, the formation of polymer crystalsomes formed by 1D polymer crystals is reported. Poly (3‐hexylthiophene) (P3HT) is chosen as the model polymer because of its 1D growth habit. P3HT crystalsomes are successfully fabricated using a miniemulsion solution crystallization method, as confirmed by scanning electron microscopy and transmission electron microscopy. X‐ray diffraction (XRD) and selected area electron diffraction experiments confirm that P3HT crystallized into a Form I crystal structure. XRD, differential scanning calorimetry and UV–Vis results reveal curvature‐dependent structural, thermal and electro‐optical properties.
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- PAR ID:
- 10390319
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Macromolecular Rapid Communications
- Volume:
- 44
- Issue:
- 1
- ISSN:
- 1022-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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