Abstract
Plasmas can generate ultra-high-temperature reactive environments that can be used for the synthesis and processing of a wide range of materials1,2. However, the limited volume, instability and non-uniformity of plasmas have made it challenging to scalably manufacture bulk, high-temperature materials3,4,5,6,7,8. Here we present a plasma set-up consisting of a pair of carbon-fibre-tip-enhanced electrodes that enable the generation of a uniform, ultra-high temperature and stable plasma (up to 8,000 K) at atmospheric pressure using a combination of vertically oriented long and short carbon fibres. The long carbon fibres initiate the plasma by micro-spark discharge at a low breakdown voltage, whereas the short carbon fibres coalesce the discharge into a volumetric and stable ultra-high-temperature plasma. As a proof of concept, we used this process to synthesize various extreme materials in seconds, including ultra-high-temperature ceramics (for example, hafnium carbonitride) and refractory metal alloys. Moreover, the carbon-fibre electrodes are highly flexible and can be shaped for various syntheses. This simple and practical plasma technology may help overcome the challenges in high-temperature synthesis and enable large-scale electrified plasma manufacturing powered by renewable electricity.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
The data supporting the findings of this study are available in the paper and source data files. Further datasets collected for this study are available from the corresponding authors on request. Source data are provided with this paper.
References
Merche, D., Vandencasteele, N. & Reniers, F. Atmospheric plasmas for thin film deposition: a critical review. Thin Solid Films 520, 4219–4236 (2012).
Massines, F., Sarra-Bournet, C., Fanelli, F., Naudé, N. & Gherardi, N. Atmospheric pressure low temperature direct plasma technology: status and challenges for thin film deposition. Plasma Process. Polym. 9, 1041–1073 (2012).
Velikhov, E. P., Golubev, V. S. & Pashkin, S. V. Glow discharge in a gas flow. Sov. Phys. Usp. 25, 340–358 (1982).
Allis, W. P. Review of glow discharge instabilities. Physica B+C 82, 43–51 (1976).
Nozaki, T., Yoshida, S., Karatsu, T. & Okazaki, K. Atmospheric-pressure plasma synthesis of carbon nanotubes. J. Phys. D. Appl. Phys. 44, 174007 (2011).
Chen, B. et al. Ion chemistry in premixed rich methane flames. Combust. Flame 202, 208–218 (2019).
Gershman, S. & Raitses, Y. Unstable behavior of anodic arc discharge for synthesis of nanomaterials. J. Phys. D. Appl. Phys. 49, 345201 (2016).
Yang, G. & Heberlein, J. Instabilities in the anode region of atmospheric pressure arc plasmas. Plasma Sources Sci. Technol. 16, 765–773 (2007).
Tachi, S., Tsujimoto, K. & Okudaira, S. Low-temperature reactive ion etching and microwave plasma etching of silicon. Appl. Phys. Lett. 52, 616–618 (1988).
Coburn, J. W. & Winters, H. F. Plasma etching—a discussion of mechanisms. J. Vac. Sci. Technol. 16, 391–403 (1979).
Liu, N. et al. Sensitive and single-shot OH and temperature measurements by femtosecond cavity-enhanced absorption spectroscopy. Opt. Lett. 47, 3171–3174 (2022).
Haas, R. A. Plasma stability of electric discharges in molecular gases. Phys. Rev. A 8, 1017–1043 (1973).
Ecker, G., Kröll, W. & Zöller, O. Thermal instability of the plasma column. Phys. Fluids 7, 2001–2006 (1964).
Ju, Y. & Sun, W. Plasma assisted combustion: dynamics and chemistry. Prog. Energy Combust. Sci. 48, 21–83 (2015).
Chung, H.-Y. et al. Synthesis of ultra-incompressible superhard rhenium diboride at ambient pressure. Science 316, 436–439 (2007).
Fukuyama, H., Nakao, W., Susa, M. & Nagata, K. New synthetic method of forming aluminum oxynitride by plasma arc melting. J. Am. Ceram. Soc. 82, 1381–1387 (1999).
Knight, R., Smith, R. W. & Apelian, D. Application of plasma arc melting technology to processing of reactive metals. Int. Mater. Rev. 36, 221–252 (1991).
Pangilinan, L. E. et al. Enhanced hardening effects on molybdenum-doped WB2 and WB2−SiC/B4C composites. Chem. Mater. 34, 5461–5470 (2022).
Riley, J., Atallah, C., Siriwardane, R. & Stevens, R. Technoeconomic analysis for hydrogen and carbon co-production via catalytic pyrolysis of methane. Int. J. Hydrogen Energy 46, 20338–20358 (2021).
Ananthanarasimhan, J., Lakshminarayana, R., Anand, M. S. & Dasappa, S. Influence of gas dynamics on arc dynamics and the discharge power of a rotating gliding arc. Plasma Sources Sci. Technol. 28, 085012 (2019).
Go, D. B. & Venkattraman, A. Microscale gas breakdown: ion-enhanced field emission and the modified Paschen’s curve. J. Phys. D. Appl. Phys. 47, 503001 (2014).
Freton, P., Gonzalez, J. J. & Gleizes, A. Comparison between a two- and a three-dimensional arc plasma configuration. J. Phys. D. Appl. Phys. 33, 2442–2452 (2000).
Haddad, G. N. & Farmer, A. J. D. Temperature determinations in a free-burning arc. I. Experimental techniques and results in argon. J. Phys. D. Appl. Phys. 17, 1189–1196 (1984).
Namihira, T. et al. Temperature and nitric oxide generation in a pulsed arc discharge plasma. Plasma Sci. Technol. 9, 747–751 (2007).
Staack, D., Farouk, B., Gutsol, A. F. & Fridman, A. A. Spectroscopic studies and rotational and vibrational temperature measurements of atmospheric pressure normal glow plasma discharges in air. Plasma Sources Sci. Technol. 15, 818–827 (2006).
Liu, N. et al. Femtosecond ultraviolet laser absorption spectroscopy for simultaneous measurements of temperature and OH concentration. Appl. Phys. Lett. 120, 201103 (2022).
Moon, S. Y., Choe, W. & Kang, B. K. A uniform glow discharge plasma source at atmospheric pressure. Appl. Phys. Lett. 84, 188–190 (2004).
Eliasson, B. & Kogelschatz, U. Nonequilibrium volume plasma chemical processing. IEEE Trans. Plasma Sci. 19, 1063–1077 (1991).
Wang, C. et al. A general method to synthesize and sinter bulk ceramics in seconds. Science 526, 521–526 (2020).
Briant, C. L. The properties and uses of refractory metals and their alloys. MRS Online Proc. Libr. 322, 305–314 (1994).
Teunissen, J. & Ebert, U. 3D PIC-MCC simulations of discharge inception around a sharp anode in nitrogen/oxygen mixtures. Plasma Sources Sci. Technol. 25, 044005 (2016).
Belan, M. & Messanelli, F. Compared ionic wind measurements on multi-tip corona and DBD plasma actuators. J. Electrostat. 76, 278–287 (2015).
Stoffels, E., Flikweert, A. J., Stoffels, W. W. & Kroesen, G. M. W. Plasma needle: a non-destructive atmospheric plasma source for fine surface treatment of (bio)materials. Plasma Sources Sci. Technol. 11, 383–388 (2002).
Ombrello, T., Qin, X., Ju, Y. & Carter, C. Combustion enhancement via stabilized piecewise nonequilibrium gliding arc plasma discharge. AIAA J. 44, 142–150 (2006).
Novoselov, A. G. et al. Turbulent nonpremixed cool flames: Experimental measurements, direct numerical simulation, and manifold-based combustion modeling. Combust. Flame 209, 144–154 (2019).
Rousso, A. C. et al. Time and space resolved diagnostics for plasma thermal-chemical instability of fuel oxidation in nanosecond plasma discharges. Plasma Sources Sci. Technol. 29, 105012 (2020).
Llewellyn-Jones, F. Ionization and Breakdown in Gases (Wiley, 1957).
Yugeswaran, S. & Selvarajan, V. Electron number density measurement on a DC argon plasma jet by stark broadening of Ar I spectral line. Vacuum 81, 347–352 (2006).
Peacock, N. J., Robinson, D. C., Forrest, M. J., Wilcock, P. D. & Sannikov, V. V. Measurement of the electron temperature by Thomson scattering in Tokamak T3. Nature 224, 488–490 (1969).
Modi, A., Koratkar, N., Lass, E., Wei, B. & Ajayan, P. M. Miniaturized gas ionization sensors using carbon nanotubes. Nature 424, 171–174 (2003).
Delikonstantis, E., Scapinello, M., Van Geenhoven, O. & Stefanidis, G. D. Nanosecond pulsed discharge-driven non-oxidative methane coupling in a plate-to-plate electrode configuration plasma reactor. Chem. Eng. J. 380, 122477 (2020).
Luong, D. X. et al. Gram-scale bottom-up flash graphene synthesis. Nature 577, 647–651 (2020).
Deng, B. et al. Phase controlled synthesis of transition metal carbide nanocrystals by ultrafast flash Joule heating. Nat. Commun. 13, 262 (2022).
Hong, Q.-J. & van de Walle, A. Prediction of the material with highest known melting point from ab initio molecular dynamics calculations. Phys. Rev. B 92, 1–6 (2015).
Buinevich, V. S. et al. Fabrication of ultra-high-temperature nonstoichiometric hafnium carbonitride via combustion synthesis and spark plasma sintering. Ceram. Int. 46, 16068–16073 (2020).
Buinevich, V. S. et al. Mechanochemical synthesis and spark plasma sintering of hafnium carbonitride ceramics. Adv. Powder Technol. 32, 385–389 (2021).
Xie, H. et al. Ta–TiOx nanoparticles as radical scavengers to improve the durability of Fe–N–C oxygen reduction catalysts. Nat. Energy 7, 281–289 (2022).
Jacob, R. J., Kline, D. J. & Zachariah, M. R. High speed 2-dimensional temperature measurements of nanothermite composites: Probing thermal vs. gas generation effects. J. Appl. Phys. 123, 115902 (2018).
Zhong, H., Mao, X., Mokrov, M. S., Shneider, M. N. & Ju, Y. 2D modeling of plasma dynamic contraction in the positive column of glow discharge. In AIAA Sci. Technol. Forum Expo, AIAA SciTech Forum 2022 https://doi.org/10.2514/6.2022-1109 (AIAA, 2022).
Zhong, H., Shneider, M. N., Mokrov, M. S. & Ju, Y. Thermal-chemical instability of weakly ionized plasma in a reactive flow. J. Phys. D. Appl. Phys. 52, 484001 (2019).
Acknowledgements
This project was not directly funded. L.H. acknowledges support from the University of Maryland A. James Clark School of Engineering. Y.J. acknowledges the Department of Energy grant support for the Plasma Science Center and NSF EFRI. J.-C.Z. acknowledges the Minta Martin Professorship fund from the University of Maryland and the Clark Distinguished Chair Professor fund from the A. James & Alice B. Clark Foundation. J.L. and K.S. acknowledge partial support from the Air Force Office of Scientific Research (AFOSR) under grant no. FA9550-22-1-0413. S/TEM research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at the Oak Ridge National Laboratory. We acknowledge the support from the University of Maryland NanoCenter and its AIMLab (Advanced Imaging and Microscopy Lab).
Author information
Authors and Affiliations
Contributions
L.H. and H.X. conceived the plasma concept. L.H., H.X., Q.Z. and S.L. carried out the plasma experimental studies, including materials syntheses. Y.J., H.X., N.L., M.N.S. and S.C. carried out the plasma instability analysis and characterization of the plasma, including Rayleigh thermometry and E-FISH measurements. J.-C.Z., J.L. and W.X. helped in planning the materials systems for the study, the shaped electrodes and sintering experiments and interpreting the results. H.X., D.L., K.S., J.L., Z.H, M.C., J.R., M.Z., X.W. and W.X. carried out the materials characterization. H.Z., X.Z. and A.D.L. conducted the plasma-related calculations. L.G. and Y.Y. conducted the cross-section polishing and SEM and EDX imaging of the MoNbTaW and Hf(C,N) samples. H.X., A.H.B., N.L. and L.H. wrote most of the paper. L.H., Y.J. and J.-C.Z. supervised the project. All authors contributed to the discussion and editing of the paper.
Corresponding authors
Ethics declarations
Competing interests
L.H., H.X., Y.J., Q.Z. and J.-C.Z. report a patent application of ‘Volumetric plasmas, and systems and methods for generation and use thereof’ filed on 3 October 2022. A startup company, USPlasma Inc., was also established to help accelerate the application of USP.
Peer review
Peer review information
Nature thanks the anonymous reviewers for their contribution to the peer review of this work.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
Extended Data Fig. 1 The carbon felt electrode for USP.
Fabrication of the carbon felt tip-enhanced electrodes. (a) Top view of a 25.4 mm diameter disk of carbon felt for the plasma electrodes. (b) Side view of the carbon felt electrode. (c) Top-view SEM image shows that the carbon felt electrode is composed of both horizontally (in-plane) and vertically-oriented (out-of-plane) carbon fibres. (d) Side-view SEM image of the carbon felt electrode showing the presence of both long and short vertically-oriented fibres. (e) Zoom-in SEM image of both the vertically-oriented short and horizontally-oriented long fibres with a vertically-oriented long fibre in the view as well. (f) Zoom-in SEM of the carbon fibres.
Extended Data Fig. 2 USP formation by the carbon fiber electrodes.
(a) Schematic of the voltage profile and corresponding photographs during the USP formation process. Before applying a voltage, the long carbon fibres come into contact across the two electrodes, with an observable resistance (1.109 kΩ) confirming the closed-circuit condition showing in (b). When applying a voltage, these long fibres generate Joule heat that ultimately deteriorates the points of contact where the resistance is highest. Eventually the fibres break, opening the circuit and resulting in a “dark” period of the plasma generation process in which no light or current signals are observed. At this stage, the resistance is infinite due to the breakage of the long fibres (c). The narrow gaps formed between the broken long fibres decrease the breakdown voltage (to ~42 V) by facilitating spark discharge via the field emission effect. Once the plasma is initialized, the densely spaced, vertically-oriented short carbon fibres of the electrode surfaces help rapidly expand the plasma to a large volume, which is accompanied by a voltage drop due to the increased conductivity of the plasma.
Extended Data Fig. 3 In-situ SEM images showing the breakage of a single carbon fibre after Joule heating was applied.
(a) The schematic shows the fibre heating setup for measurement of the resulting gap distance, in which a single carbon fibre is glued with silver paste onto a copper electrode stage and a voltage is applied to the fibre during SEM imaging. (b) SEM images of the fibre before Joule heating show a defective region in the fibre and SEM images of the fibre after Joule heating show that due to excessive heating, part of the carbon fibre is deteriorated, generating a small gap of ~3–5 μm—smaller than the diameter of the original fibre. The two edges of the fibre were also sharpened.
Extended Data Fig. 4 The stability and uniformity of USP during 10 min operation.
(a) The plasma was stable once initialized, running here for 10 min until we stopped the power supply. We set t = 0 when the gas discharge breakdown took place, and the plasma was on. The gap distance between the two electrodes was ~3 mm and the input current was 20 A. (b) SEM images demonstrating how the carbon fibre tip morphology changes before, immediately after the plasma initiation, and after 10 min of plasma operation. The vertical carbon fibres initially featured blunt tips and had sharper tips after the plasma generation, which were retained even after 10 min of plasma operation. (c) Numerical simulations demonstrating the evolution of the plasma over time. The scale bar indicates the electron number density. An initial thermal perturbation is set at the time point t = 0. The plasma usually tends to contract from a uniform and volumetric state, which is believed to be triggered by a change in the near-electrode plasma layers with time. Near the electrode surface, there are layers that release large amounts of heat, in which the thickness of the near-electrode layers is much smaller than the gap distance between the two electrodes. Here for simplicity, we treat the dynamics of the near-electrode layers as the initial temperature gradients near the electrode. The initial temperature gradients in the tip-enhanced electrode induced plasma are dispersed. The plasma density initially concentrates at the fibre tips, followed by homogenous expansion across the surface of the electrode to produce a uniform plasma.
Extended Data Fig. 5 The temperature profile of USP.
(a) Measurement of the plasma temperature via the grey body radiation spectra when the current was 20 A (~4 A/cm2). The plasma was initialized at ~1000 ms after the camera started to film. The power was then turned off from the electrodes at ~2500 ms. Upon initiation of the plasma, the temperature rapidly increases to ~4500 K. This measurement was consistent with the Rayleigh thermometry results. Note that the measurement accuracy of grey body radiation spectroscopy is ± 100 K. (b) Spatial temperature distribution of the plasma measured in-situ using Rayleigh scattering. A line scan showed the temperature was ~4700 K across the center of the plasma. The carbon tip array electrodes featured a diameter of 25.4 mm, with a gap of ~3 mm between the electrodes. The plasma was generated using a current of 20 A (4 A/cm2). (c) The numerically simulated temperature distribution in the regions near the carbon fibre tips when the plasma is on. Numerical simulation shows the carbon tips featuring a lower temperature distribution, reaching just ~3000 K even when the plasma center is set at 7000 K. We attribute this to the high thermal conductivity and emissivity of the carbon tips, which helps rapidly transfer heat away from the electrodes. The scale bar is 20 μm.
Extended Data Fig. 6 Control experiments demonstrating the critical roles of the fibre tips.
(a) Experimental setup of the stainless-steel plate electrodes (diameter = 25.4 mm), in which no carbon fibres were utilized. The corresponding current-voltage hysteresis loop indicates a gas discharge breakdown voltage of nearly 1,500 V over a ~3 mm gap was required, with the resulting plasma discharge occurring at random in narrow channels. (b) Carbon felt electrodes without long fibres. When there were no long fibre contacts, no spark discharge or plasma was formed. The voltage was increased from 0 to 80 V and no current was detected. (c) Schematic and photos of graphite plate electrodes with only a few long fibres connecting between them. We used 25.4 mm diameter graphite disks and glued a bundle of long carbon fibres to the center region, thus eliminating the effect of the short carbon fibres. The carbon fibre bundles were in contact with both the top and bottom graphite disks. (d) Control experiment for the plasma ignition without the short fibre tip array, in which the process used only long carbon fibres (as shown in (c)). The voltage was gradually elevated to 50 V, with corresponding photos of the electrodes shown. Obvious sparks can be seen in the photos as the voltage was increased to above ~40 V. However, due to the lack of short carbon fibres on the electrodes, the sparks did not lead to the formation of a continuous plasma and did not expand the plasma area across the graphite disk electrode. (e) Schematic showing the different stages for the electrodes with only long fibres when increasing the applied voltage. No continuous or stable plasma is formed.
Extended Data Fig. 7 Breakdown voltage measurements.
(a) The breakdown voltage (41.6 ± 2.6 V, s.d.) for 15 pairs of the carbon fibre tip-enhanced electrodes. New electrodes were used for each measurement. (b) The breakdown voltage measurements, repeated 15 times, for the same pair of carbon fibre tip-electrodes with an average of 44.3 ± 4.4 V (s.d.).
Extended Data Fig. 8 The applications of USP for various materials synthesis.
(a) SEM images and EDS mapping results of the W-1.5Nb-0.5Ti alloy cross section, in which the ultrahigh-temperature plasma (4700 K, ~10 s) readily melted the precursors to form a dense alloy with uniform distribution of the W, Nb, and Ti elements. (b) The W-1.5Nb-0.5Ti (wt%) sample made by arc melting. It is challenging to synthesize W-rich refractory alloys via arc melting since it is difficult for the tungsten cathode of the arc melter to generate a sufficiently high temperature to fully melt the tungsten. During arc-melting of this tungsten alloy, we observed pronounced heterogeneity in the microstructure, which indicated that the alloy elements were unable to melt uniformly, displaying notable segregation. It typically takes three to five times for arc melted samples to reach somewhat acceptable homogeneity. (c) Microstructural images of three W-1.5Nb-0.5Ti samples melted with different currents using a BJ-338 arc-melter from the Materials Research Furnace Inc. The starting materials were the elementary powders of W, Nb, and Ti. The currents were 280 A, 315 A, and 350 A for sample #1, sample #2, and sample #3, respectively. (d) Schematic and images demonstrating the direct synthesis of CNTs from carbon black via USP (~6600 K, ~10 s) without a catalyst. SEM and TEM images demonstrate the transition of carbon black to multiwalled CNTs composed of ~5–15 carbon layers after the USP treatment. (e) TEM image of a CNT and its ends. No metal nanoparticles were observed at the nanotube ends, confirming that no catalyst was involved in the synthesis. EELS analysis of the CNTs shows a typical carbon K edge profile. This approach could potentially improve the accessibility of CNTs, particularly by using low-cost carbon black (a byproduct of the petroleum industry) as a starting material.
Extended Data Fig. 9 The USP electrodes with different form factors.
(a) Photos comparing the size of carbon felt electrodes with diameters of 25.4 mm and 60 mm, respectively. The area is enlarged by ~6-fold. (b) Ignition and stabilization of plasma between the 60 mm diameter electrodes. The gap distance between the two carbon felt electrodes was 10 mm. (c) The ignition and formation of plasma using electrodes with wider gap distances, including a 8 mm gap for the 25.4 mm diameter electrode, and a 18–20 mm gap for the 60 mm diameter electrode. (d) A coaxial carbon felt rod-tube structure to form a plasma-filled channel. The carbon felt rod serves as the cathode and the carbon felt tube is the anode. The metal hook is a current collector.
Extended Data Fig. 10 The plasma sintering/fusion process using a focused plasma beam.
(a) Schematic of the plasma sintering/fusion process. (I) The carbon felt electrodes are first placed directly across from each other. (II) The voltage is then elevated to realize the plasma breakdown. (III) With the aid of the short tip array, the plasma is spread and stabilized. (IV) The bottom carbon felt electrode then carries the sample to go under the plasma to realize sintering/fusion. (b) Photos showing the plasma fusion process. The pellet is carried by the carbon felt strip to scan the sample beneath the plasma heating region using a programmed route until the sample is well sintered. The scale bar shows the position of the sample. (c) Cross-sectional SEM image of a large tungsten sample achieved by the USP powder bed fusion/sintering process. (d) Cross-sectional SEM image of a high entropy diboride (HEB) coating on a Nb-10Hf-1Ti alloy substrate, in which good bonding was achieved without any gap between the coating and substrate.
Supplementary information
Supplementary Video 1
A typical video of the USP process with increasing voltage from 0 V to 42 V
Supplementary Video 2
10 min stability of USP at 18 V, 20 A
Supplementary Video 3
20 USP pulses by switching the voltage between 0 V and 45 V in 0.5 s and maintaining the turn-on current at 35 A for 1 s
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Xie, H., Liu, N., Zhang, Q. et al. A stable atmospheric-pressure plasma for extreme-temperature synthesis. Nature 623, 964–971 (2023). https://doi.org/10.1038/s41586-023-06694-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41586-023-06694-1
This article is cited by
-
Enhancements of electric field and afterglow of non-equilibrium plasma by Pb(ZrxTi1−x)O3 ferroelectric electrode
Nature Communications (2024)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
