Superconductivity in Metastable K1+δMo6Se8: A Potassium-Intercalated Chevrel Phase

作者：Yunqing Shi, Xiaoping Ma, Le-Wei Chen, Junkun Yi, Menghu Zhou, Yadong Gu, Qingsong Yang, Jianqi Li, Huai-Xin Yang, Bin-Bin Ruan, Zhi-An Ren · 发表于：Journal of the American Chemical Society · 年份：2025 · DOI：10.1021/jacs.5c01401 · 被引用次数：5 · 研究领域：Inorganic Chemistry and Materials、Iron-based superconductors research、Nanocluster Synthesis and Applications

The Chevrel phase (CP), characterized by its unique Mo 6 X 8 (X = S, Se, Te) cluster structure, represents a class of promising materials demonstrating exceptional performance in various applications, including battery cathodes, electrocatalysts, and superconductors. However, the exploration of new CP derivatives remains challenging due to the inherent lattice destabilization caused by cation intercalation, particularly evident in selenide and telluride systems. This study reports the successful synthesis of thermodynamically metastable K 1+ δ Mo 6 Se 8 ( δ ∼ 0.37) and the superconducting properties therein. K 1+ δ Mo 6 Se 8 crystallizes in the triclinic space group P 1̅ (No. 2), where potassium cations occupy interstitial sites between the Mo 6 Se 8 clusters. Comprehensive characterization through electrical resistivity, magnetization, and specific heat measurements reveals bulk superconductivity at T c = 8.9 K. Notably, the upper critical field is estimated to be 26.4 T, violating the Pauli paramagnetic limit. Furthermore, low-temperature specific heat analysis indicates possible multigap superconducting behavior. Our findings not only expand the family of high-critical-field superconducting CPs but also demonstrate the potential to synthesize novel CP materials through solid-state reactions at lower temperatures.