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Complete Thermally Driven 1T-to-2H Phase Transition in TaSe2
Yucheng Zhu1, Jiyuan Xu1, Jie Cheng1
1School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Nano Letters
|July 27, 2026
Summary
Researchers achieved a complete 1T-to-2H phase transition in tantalum diselenide (TaSe2) using heat. This controlled transition, verified by spectroscopy and electrical tests, advances phase engineering in 2D materials.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Two-dimensional (2D) materials offer tunable electronic properties through phase engineering.
- Tantalum diselenide (TaSe2) exists in 1T and 2H polytypes with distinct electronic phases.
- Achieving and verifying a complete 1T-to-2H phase transition in TaSe2 is experimentally challenging.
Purpose of the Study:
- To report a complete, thermally driven 1T-to-2H phase transition in TaSe2.
- To distinguish between the 1T and 2H phases using electronic and vibrational signatures.
- To support the broader field of phase engineering in 2D materials.
Main Methods:
- Angle-resolved photoemission spectroscopy (ARPES) to probe electronic structure.
- Raman spectroscopy to analyze vibrational modes (phonons).
- In situ monitoring of Raman-active phonon modes during thermal transition.
- Photoluminescence and electrical transport measurements for verification.
Main Results:
- Demonstrated a complete thermally induced 1T-to-2H phase transition in TaSe2.
- Observed distinct electronic and vibrational fingerprints for each phase.
- Tracked the transition in situ via phonon mode evolution and electronic structure changes.
- Confirmed transition completeness using photoluminescence and transport measurements.
Conclusions:
- The study successfully achieved and verified a complete 1T-to-2H phase transition in TaSe2.
- Distinct spectroscopic signatures confirm the phase transformation.
- Findings enhance understanding of TaSe2 phase transitions and aid 2D material phase engineering.
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