ASYMMETRIC INTERCALATION OF TRANSITION METAL CHALCOGENIDES

Abstract

Layered transition metal chalcogenides (TMCs) offer a versatile platform for novel quantum properties through intercalation chemistry. By intercalating molecular species into the van der Waals gaps, one can modulate the host structure, tune electronic correlations, and even break the symmetries of the structure. In particular, the use of polar and chiral amines enables the disruption of inversion symmetry, giving rise to polar metallic states or enhanced superconducting behavior. This dissertation investigates the intercalation of amines, including chiral molecules, into layered transition metal chalcogenides (TMCs) through hydrothermal and solvothermal synthesis. By inserting organic molecules into the gaps between the layers of inorganic hosts, new hybrid materials were constructed with tunable electronic and magnetic properties. A polar ferromagnetic metal was realized by intercalating [Co(en)₃]²⁺ complexes into CoS, where hydrogen bonding disrupts inversion symmetry while preserving metallic conductivity. Chiral amine intercalation into TaSe₂ was shown to enhance its superconducting transition temperature (Tc) up to 7 K. To probe the mechanisms underlying intercalation and crystallization, in-situ synchrotron powder X-ray diffraction was applied to monitor time-resolved structural evolution under eight different hydrothermal and solvothermal conditions. The study revealed differences in crystallization kinetics and intermediate phases, depending on precursor chemistry and solvent properties.