Ultra-rapid processing of refractory carbides; 20 s synthesis of molybdenum carbide, Mo₂C

Abstract

The microwave synthesis of molybdenum carbide, Mo(2)C, from carbon and either molybdenum metal or the trioxide has been achieved on unprecedented timescales; Ex- and in-situ characterisation reveals key information as to how the reaction proceeds.

Rapid, energy-efficient synthesis of the layered carbide, Al4C3

“…17 We have shown previously that the use of microwaves can facilitate the synthesis of carbides over second timescales. [18][19][20][21] Microwaves are particularly well-suited to the synthesis and processing of carbides, with carbon acting as both a starting material and a microwave susceptor. 17 Further attractions of MW processing are the opportunities offered to access new and metastable materials 22 and to rationalise the interaction of solids with electromagnetic fields.…”

“…In our previous work in M-C systems (where M = W, Mo, Nb and Ta) a general behaviour in the interaction of these systems with microwaves has been observed. [19][20][21]36,37 This behaviour is rationalised by considering the loss tangent, tan δ ( = ε″ / ε′), which describes the ability of a material (at a specific temperature and frequency) to absorb microwave energy and dissipate heat; 34 Initially energy is absorbed by the carbon susceptor (loss tangent up to 2.95; c.f. loss tangent of water 0.118, at 2.45 GHz and 298 K 38 ) then as the temperature increases the dielectric properties of the reactant mixture reach an optimum point where tan  is at a maximum.…”

Hydrogen Evolution Reaction of γ-Mo0.5W0.5 C Achieved by High Pressure High Temperature Synthesis

“…Wan et al synthetized four phases of molybdenum carbide (α-MoC1−x, β-Mo2C, η-MoC, and γ-MoC), studied and compared the catalytic performances for multiple phases of molybdenum carbide [20,21]. The main synthetic methods of TMCs are as below: the direct carbonization of transition metal oxides [22], chemical vapor deposition (CVD) [23], the self-propagating high-temperature synthesis (SHS) [24], and microwave treatment [25]. Additionally, high-pressure, high-temperature (HPHT) is an effective way to prepare TMCs.…”

“…The main synthetic methods of TMCs are as below: the direct carbonization of transition metal oxides [22], chemical vapor deposition (CVD) [23], the self-propagating high-temperature synthesis (SHS) [24], and microwave treatment [25]. Additionally, high-pressure, high-temperature (HPHT) is an effective way to prepare TMCs.…”

Ultrarapid Microwave Synthesis of Superconducting Refractory Carbides

“…[15,16] Common to all these M-C systems is a critical temperature at which product formation is initiated. Once reached, the formation of the carbides is subsequently extremely rapid, resulting in phase-pure products.…”