A Tungsten-Based Nanolaminated Ternary Carbide: (W,Ti)₄C_{4- x}

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Chemistry

Background:

• Nanolamellar transition metal carbides, including their two-dimensional (2D) derivatives, are of significant interest.
• These materials show promise in energy storage, catalysis, transparent conductive coatings, and medicine.
• Development of novel 2D materials necessitates the synthesis of new nanolaminated structures.

Purpose of the Study:

• To synthesize a novel tungsten-based nanolaminated ternary carbide phase.
• To characterize the atomic structure, ordering, and occupancies of the synthesized phase.
• To explore the potential of aluminum catalysis in synthesizing new transition metal carbides.

Main Methods:

• Synthesis of (W,Ti)4C4-x via an Al-catalyzed reaction of W, Ti, and C powders at 1600 °C for 4 hours under flowing argon.
• Utilized X-ray and neutron diffraction for atomic structure determination.
• Employed Z-contrast scanning transmission electron microscopy for structural analysis.

Main Results:

• Successfully synthesized a layered hexagonal phase, (W,Ti)4C4-x (space group P63/mmc).
• Determined lattice parameters a = 3.00880(7) Å and c = 19.5633(6) Å.
• Revealed a structure composed of pure W layers alternating with mixed W/Ti atomic layers, with a nonstoichiometric carbon content.

Conclusions:

• Aluminum catalysis enables the synthesis of complex nanolaminated ternary transition metal carbides.
• This method allows for the creation of otherwise difficult-to-synthesize phases.
• The findings could lead to the discovery of a broad family of nonstoichiometric ternary carbides under relatively mild conditions.