Unveiling the pressure-driven metal–semiconductor–metal transition in the doped TiS2

Abstract

Abstract Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands, leading to increased electrical conductivity. Here, we report the electrical properties of the doped 1T-TiS2 under high pressure by electrical resistance investigations, synchrotron x-ray diffraction, Raman scattering and theoretical calculations. Up to 70 GPa, an unusual metal–semiconductor–metal transition occurs. Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17 GPa is due to the electron localization induced by the intercalated Ti atoms. This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms, and the Anderson localization arising from the disordered intercalation. At pressures exceeding 30.5 GPa, the doped TiS2 undergoes a re-metallization transition initiated by a crystal structure phase transition. We assign the most probable space group as P212121. Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.