Melting Point and Sublimation of Molybdenum Disulphide

Cannon, Peter

doi:10.1038/1831612a0

Cited by 37 publications

(21 citation statements)

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“…In addition, it reaches its estimated melting point at 0.02 to 0.03 seconds after ignition. The melting point of MoS 2 is uncertain, being reported as 1923 K to 1973 K by Zelikman and Belayaeskaya, [17] whereas Cannon [18] measured approximately 2073 K. After being corrected by applying Tammann's rule, this temperature is measured at 2646 K. These values, however, do not agree with the experimental results, which in the partially reacted samples collected no evidence of melting or cenosphere formation was found. One possible explanation for this [19] and Zelikman and Belayaeskaya [17] found that at 1923 K to 1973 K molybdenite melts with simultaneous decomposition to molybdenum sesquisulfide (Mo 2 S 3 ) generating gaseous sulfur according to:…”

Section: Discussionmentioning

confidence: 45%

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Wilkomirsky

Otero²,

Balladares

2009

Metall Mater Trans B

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The kinetics and reaction mechanism of the flash oxidation of +35/-53 lm molybdenite particles in air, as well as in 25, 50, and 100 pct oxygen higher than 800 K, has been investigated using a stagnant gas reactor and a laminar flow reactor coupled to a fast-response, twowavelength pyrometer. The changes in the morphology and in the chemical composition of partially reacted particles were also investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal analysis (DTA), and electron microprobe. High-speed photography was also used to characterize the particle combustion phenomena. The effects of oxygen concentration and gas temperature on ignition and peak combustion temperatures were studied. The experimental results indicate that MoS 2 goes through a process of ignition/combustion with the formation of gaseous MoO 3 and SO 2 with no evidence of formation of a molten phase, although the reacting molybdenite particles reach temperatures much higher than their melting temperature. This effect may be a result of the combustion of gaseous sulfur from partial decomposition of molybdenite to Mo 2 S 3 under a high gas temperature and 100 pct oxygen. In some cases, the partial fragmentation and distortion of particles also takes place. The transformation can be approximated to the unreacted core model with chemical control and with activation energy of 104.0 ± 4 kJ/mol at the actual temperature of the reacting particles. The reaction was found to be first order with respect to the oxygen concentration. The rate constant calculated at the actual temperatures of the reacting particles shows a good agreement with kinetic data obtained at lower temperatures. The ignition temperature of molybdenite shows an inverse relationship with the gas temperature and oxygen content, with the lowest ignition temperature of 1120 K for 100 pct oxygen. Increasing the oxygen content from 21 to 100 pct increases the particle combustion temperature from 1600 K to more than 2600 K. A high oxygen content also resulted in a change of the reaction mechanism from relatively constant combustion temperatures in air to much faster transient combustion pulses in pure oxygen.

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Section: Discussionmentioning

confidence: 45%

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Wilkomirsky

Otero²,

Balladares

2009

Metall Mater Trans B

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“…The low oxygen partial pressure in our vacuum chamber allows the MoS 2 to reach such high temperatures without oxidation. Reports on the melting point of monolayer MoS 2 are lacking, but melting of bulk material was found to arise at temperatures >1923 K. Our measurements are well described by Planck's law, even though the small size of the emission spot ( d rad < hc / E 0 ) places it outside the thermodynamic limit regime . From a practical point of view, our results are also important with regard to the miniaturization of TMD‐based electronic devices.…”

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confidence: 60%

Thermal Light Emission from Monolayer MoS₂

et al. 2017

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Layered transition metal dichalcogenide semiconductors, such as MoS and WSe , exhibit a range of fascinating properties and are being currently explored for a variety of electronic and optoelectronic devices. These properties include a low thermal conductivity and a large Seebeck coefficient, which make them promising for thermoelectric applications. Moreover, transition metal dichalcogenides undergo an indirect-to-direct bandgap transition when thinned down in thickness, leading to strong excitonic photo- and electroluminescence in monolayers. Here, it is demonstrated that a MoS monolayer sheet, freely suspended in vacuum over a distance of 150 nm, emits visible light as a result of Joule heating. Due to the poor transfer of heat to the contact electrodes, as well as the suppressed heat dissipation through the underlying substrate, the electron temperature can reach ≈1500-1600 K. The resulting narrow-band light emission from thermally populated exciton states is spatially located to an only ≈50 nm wide region in the center of the device and goes along with a negative differential electrical conductance of the channel.

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“…For simplicity, our effective material model adopts temperatureindependent mechanical properties (density ρ, Young's modulus E, yield stress σ yield , and critical strain crit ) equivalent to those of thin-film polycrystalline MoS 2 at 300 K [35][36][37], and also uses the ultra-high vacuum sublimation temperature of bulk MoS 2 T sub ≈ 1000 K [38,39] as the thermal limit. For the effective optical properties, we use a 90%/10% weighted average of the room-temperature complex index of refraction values (n and κ) of MoS 2 [40] and Al 2 O 3 [41,42], respectively.…”

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confidence: 99%

“…To aid this discussion, we have plotted twelve relevant quantities, including m s , t f , P max , T max , σ max , L, a , α a , ε e , and three others that we will introduce below, as a function of d s and s s in Figure 3 for a m tot = 2 g sailcraft accelerated by a constant laser output power of Φ 0 = 30 GW (see Supplementary Information). In these panels, as labeled in Figure 3(a), we have removed designs for which the curvature would result in multiple reflections and cause excessive heating in the cen-ter of the sail s s < ds √ 2 , designs hot enough to sublimate the material, T max > T sub ≈ 1000 K [38,39], and designs that would tear, σ max > σ yield ≈ 1000 MPa [36,37]. Importantly at low diameters d s , few persisting light sail designs exhibit large radii of curvature s s , which underscores the the imperative that light sails should be curved (higher s s values imply flatter structures).…”

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confidence: 99%

Relativistic light sails need to billow

Campbell,

Brewer,

Jariwala

et al. 2021

Preprint

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We argue that light sails that are rapidly accelerated to relativistic velocities by lasers must be significantly curved in order to reduce their mechanical stresses and avoid tears. Using an integrated opto-thermo-mechanical model, we show that the diameter and radius of curvature of a circular light sail should be comparable in magnitude, both on the order of a few meters in optimal designs for gram-scale payloads. Moreover, when sufficient laser power is available, a sail's acceleration length decreases and its chip payload capacity increases as its curvature increases. Our findings provide guidance for emerging light sail design programs, which herald a new era of interstellar space exploration.

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Melting Point and Sublimation of Molybdenum Disulphide

Cited by 37 publications

References 1 publication

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Thermal Light Emission from Monolayer MoS₂

Relativistic light sails need to billow

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Melting Point and Sublimation of Molybdenum Disulphide

Cited by 37 publications

References 1 publication

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Kinetics and Reaction Mechanisms of High-Temperature Flash Oxidation of Molybdenite

Thermal Light Emission from Monolayer MoS2

Relativistic light sails need to billow

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Thermal Light Emission from Monolayer MoS₂