Pressure-induced metallization and 3d-like behavior in TcS₂

Area of Science:

• Solid-state physics
• Materials science
• High-pressure physics

Background:

• Technetium disulfide (TcS2) exhibits a charge transfer insulator to metal transition.
• Understanding high-pressure phases of transition metal dichalcogenides is crucial for materials discovery.

Purpose of the Study:

• To investigate the high-pressure behavior of TcS2.
• To explore the formation and recoverability of novel high-pressure phases.
• To characterize the structural and bonding properties of these phases.

Main Methods:

• High-pressure synthesis using laser annealing.
• X-ray diffraction for structural analysis.
• Analysis of bonding characteristics.

Main Results:

• TcS2 undergoes a metal transition above 28 GPa.
• A kinetically hindered arsenopyrite phase was discovered under high pressure.
• This phase is recoverable to ambient conditions.
• The new phase exhibits structural similarities to Mn-dichalcogenides, not Re-dichalcogenides.
• Formation of S-S and Tc-Tc bonds was observed in the high-pressure phase.

Conclusions:

• Laser annealing is effective in stabilizing unique high-pressure phases of TcS2.
• The discovered phase represents a new structural motif for transition metal dichalcogenides.
• The presence of S-S and Tc-Tc bonds offers insights into bonding under extreme conditions.