Pressure-induced iso-structural phase transition and metallization in WSe2
Xuefei Wang1, Xuliang Chen1, Yonghui Zhou1
1Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, CAS and University of Science and Technology of China, Hefei 230031, China.
Scientific Reports
|May 5, 2017
Summary
High pressure transforms tungsten diselenide (WSe2) through layer sliding, inducing metallization. In-plane strain plays a key role in this pressure-induced structural and electronic phase transition.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Tungsten diselenide (WSe2) is a layered transition metal dichalcogenide with potential electronic applications.
- Understanding its behavior under extreme conditions like high pressure is crucial for exploring novel material properties.
Purpose of the Study:
- To investigate the structural and electronic properties of single-crystal WSe2 under high pressure.
- To determine the pressure-induced phase transitions and metallization mechanisms in WSe2.
Main Methods:
- In situ high-pressure synchrotron X-ray diffraction (XRD) and Raman spectroscopy.
- Electrical transport measurements using diamond anvil cells up to ~63 GPa.
- Low-temperature measurements down to 1.8 K.
Main Results:
- An iso-structural phase transition via layer sliding was observed starting at 28.5 GPa, completing around 60 GPa.
- In-plane strain was found to be more critical than out-of-plane compression for inducing the transition.
- Pressure-induced metallization occurred over a broad range (28.2–61.7 GPa), showing mixed semiconducting and metallic behavior.
Conclusions:
- High pressure drives a unique layer-sliding phase transition in WSe2.
- The transition leads to metallization, with in-plane strain being a significant factor.
- Coexistence of low- and high-pressure phases explains the observed mixed electronic properties.
More Related Videos
Related Concept Videos
01:21Phase Transitions
11
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
11
02:31Phase Transitions
23.5K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
23.5K
02:39Phase Transitions: Melting and Freezing
15.4K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
15.4K
02:33Phase Transitions: Sublimation and Deposition
20.5K
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
20.5K
01:19Phase Diagram
7.1K
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
7.1K
02:39Phase Diagrams
50.9K
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
50.9K