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Equilibrium chemistry of boron halides in plasma chemical reactors

  • High purity halides of III-VI group elements, especially chloride and fluorides, are used in gas phase technologies for obtaining high purity materials and coatings. The reduction of halides in hydrogen-halide mixtures can be achieved in various discharge plasmas, e.g. inductively coupled, ark, and even laser-induced plasmas. Existing models of such plasmas are not sufficiently accurate to predict a yield of the targeted compounds and to describe the plasma processes involved in formation of these compounds. Besides, a construction of costly plasma-chemical reactors can be alleviated by the prior modeling of plasma processes that may occur in such reactors. A goal of this work is to extend the model, which was initially developed for laser induced Plasmas, to plasmas used in chemical reactors, in particular, the inductively-coupled-RF discharge Plasma. The model predicts equilibrium chemical compositions of reaction mixtures as functions of plasma temperature and stoichiometry ofHigh purity halides of III-VI group elements, especially chloride and fluorides, are used in gas phase technologies for obtaining high purity materials and coatings. The reduction of halides in hydrogen-halide mixtures can be achieved in various discharge plasmas, e.g. inductively coupled, ark, and even laser-induced plasmas. Existing models of such plasmas are not sufficiently accurate to predict a yield of the targeted compounds and to describe the plasma processes involved in formation of these compounds. Besides, a construction of costly plasma-chemical reactors can be alleviated by the prior modeling of plasma processes that may occur in such reactors. A goal of this work is to extend the model, which was initially developed for laser induced Plasmas, to plasmas used in chemical reactors, in particular, the inductively-coupled-RF discharge Plasma. The model predicts equilibrium chemical compositions of reaction mixtures as functions of plasma temperature and stoichiometry of reactants. The mixtures investigated are BCl3/H2/Ar and BF3/H2/Ar where Ar serves as the plasma-forming gas and H2 as a binding agent which binds the active species Cl and F and Cl- and F-containing intermediates to produce gaseous B and its condensate. An additional goal is to obtain information about intermediate reaction products for different ratios of BCl3/H2 and BF3/H2 and at different temperatures and different Ar flow rates. It is found that the desired components B and B2 appear at appreciable concentrations of >0.1% and ~0.01% respectively only at temperatures above 3000 K. It is also established that the effect of charged species on the reaction products is miniscule for temperatures below 5000 K. The expected yield of boron as a function of the original mole fraction H2/BCl3 and H2/BF3 is calculated. The mole fractions are varied in the range 0.1-1000 and the temperature in the range 1000-10000 K. It is shown that the yield of boron increases with increasing the molar ratio H2/BCl3 and H2/BF3 up to ~100 in the temperature range 2000-5000 K. At higher temperatures, T>5000 K, the boron concentration reaches its maximum and does not depend on the concentration of hydrogen; all molecules dissociate and chemical reactions proceed only between charged particles (mostly elemental ions) and electrons. The calculated plasma parameters and composition are compared with experimental data obtained by optical emission spectroscopy. The calculated plasma temperature and electron density are shown to be in good agreement with the measured ones.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Igor Gornushkin
Koautoren/innen:S. Sergei, R.A. Kornev, P. G. Sennikov
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2019
Organisationseinheit der BAM:1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.9 Chemische und optische Sensorik
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Chemical reactors; LIBS; Laser induced plasma; Plasma diagnostics; Plasma modeling
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Analytical Sciences / Spurenanalytik und chemische Zusammensetzung
Veranstaltung:European Winter Conference on Plasma Spectrochemistry (EWSPS-2019)
Veranstaltungsort:Pau, France
Beginndatum der Veranstaltung:03.02.2019
Enddatum der Veranstaltung:08.02.2019
Verfügbarkeit des Volltexts:Volltext-PDF im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:18.03.2019
Referierte Publikation:Nein