Gene-Inherited [Se2] Dimers in a Reactive Salt Flux: Synthesis of a Quasi-One-Dimensional NbSe2 Superconductor

Transition metal dichalcogenides (TMDs) have attracted much attention due to their excellent properties in many fields. The existing thermodynamically stable TMDs are almost two-dimensional or three-dimensional in structure; therefore, the synthesis of new kinetic stable TMDs with lower dimensions is of great significance in materials science and chemistry. Here, we demonstrated the synthesis of a new type of NbSe₂ with one-dimensional (1D) Nb[Se₂] chains by using K₂Se₂ with low melting points as the reactive salt fluxes. In this reaction, the [Se₂] dimers in K₂Se₂, acting like "genes", are "inherited" by the 1D-NbSe₂, reducing the dimension of the material to 1D and generating a new metastable phase. Several measurements confirmed the existence of a 1D chain structure from the aspects of morphology, structure, oxidation valence state, and phonon vibration. Magnetic and electrical property measurements show that the samples behave as paramagnetic metals in the normal state and exhibit superconductivity below 9.5 K. In this work, we highlight the opportunity to gain a series of low-dimensional new type MQ2 (M = metal, Q = S, Se, Te) that will inspire future efforts in material science.