Abstract
2M-WS2 is a metastable, superconducting polymorphofthe transition metal dichalcogenide (TMD) WS2, comprisedof layers of face-sharing distorted WS6 octahedra. It ispredicted to host non-Abelian quantum states, promising for topologicalcomputing. Due to its thermodynamic instability, 2M-WS2 cannot be synthesized using solid-state synthesis. Rather, it requiresa top-down approach in which K+ is ...
Abstract
2M-WS2 is a metastable, superconducting polymorphofthe transition metal dichalcogenide (TMD) WS2, comprisedof layers of face-sharing distorted WS6 octahedra. It ispredicted to host non-Abelian quantum states, promising for topologicalcomputing. Due to its thermodynamic instability, 2M-WS2 cannot be synthesized using solid-state synthesis. Rather, it requiresa top-down approach in which K+ is deintercalated fromK( x )WS(2); so far, this processhas been completed using a strong oxidizer, K2Cr2O7 in dilute H2SO4. A disadvantageof such an indirect synthesis is that the harsh reaction conditionmay cause the crystal quality to suffer. To date, no studies havebeen performed to optimize the synthesis or understand the chemicalnature of this reaction. In this study, we found that the K-deintercalationprocess from K x WS2 is spontaneous,and a non-oxidative acidic reaction environment is sufficient to facilitatethe oxidation of K x WS2 to 2M-WS2 while reducing H+ to H-2. By analyzingthe superconducting transition in the heat capacity, we found that2M-WS2 made using less aggressive methods has higher superconductingvolume fractions. We describe how to access the thermodynamicallyunfavorable superconducting 2M phase of WS2 as high-qualitycrystals.
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