Effect of metal fluorides in the electrolyte on the electrolytic production of NF3

Tasaka, Akimasa; Osada, Toshinori; Kawagoe, Tomoo; Kobayashi, Megumi; Takamuku, Atsushi; Ozasa, Kohtaro; Yachi, Tomonori; Ichitani, Toshiyuki; Morikawa, Katsuhiko

doi:10.1016/s0022-1139(97)00140-1

Cited by 18 publications

(10 citation statements)

References 5 publications

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“…Electrolysis was conducted with the nickel cell at 100°C. Although the water content was high before start-up, it might be decreased by electrolysis to less than 0.02 wt % within 80 h. 9 The anode gas was treated with NaF to eliminate HF before the chromatographic and IR spectroscopic analyses. 1 The current efficiencies for the constituents were evaluated from the results of gas analysis and the flow rate of anode gas.…”

Section: Methodsmentioning

confidence: 99%

Preparation of a Nickel-Nickel Oxide Composite by Hot Isostatic Pressing and Its Application for Anodes Used in Electrolytic Production of Nitrogen Trifluoride

Tasaka

Suzuki

Oshida

et al. 2003

J. Electrochem. Soc.

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O, and its composition was almost the same as that at the Ni sheet anode. The current efficiency for NF 3 formation on the Ni-NiO composite anode from mixture of NiO and Ni powders was high compared with that on the Ni-NiO 1ϩx composite anode from the mixture of LiNiO 2 and Ni powders. The best current efficiency for NF 3 formation was ca. 53% on the Ni 5 mol % NiO composite anode, and it was almost the same as that of the Ni sheet anode. The addition of LiF in a molten NH 4 F•2HF increased it, presumably because of deposition of Li 2 NiF 6 on the anode. On the other hand, the anode consumption of the Ni-NiO composite was much smaller compared with that of the Ni sheet electrode. Also, the oxygen content in the oxidized layer formed on the Ni-NiO composite anode was high compared with that on the Ni sheet anode. The scanning electron microscope observation revealed that the surface of the Ni-NiO composite anode was covered with the compact film having some defects. From these results, it is concluded that the Ni-NiO composite anode is favorable for electrolytic production of NF 3 , and that the oxidized layer on the anode has a high resistance to corrosion, because of the compact film containing a higher content of oxygen formed on the anode.A large amount of nitrogen trifluoride (NF 3 ) is consumed as a dry etchant and a cleaner gas for the chemical vapor deposition ͑CVD͒ chamber by the electronic industry in Japan. Pure NF 3 free from carbon tetrafluoride (CF 4 ) can be obtained by the electrolysis of NH 4 F•2HF with a nickel anode to meet the demand. However, a relatively large corrosion rate and passivation of the nickel anode are problems for electrolytic production of NF 3 . According to the previous works, 1-3 the nickel dissolution is diminished by a trace of water in the melt whereas the current efficiency for NF 3 formation decreases. The surface layer on the anode formed in a molten salt containing water was dense and adhesive, and its oxygen content was high. 2,3 When the oxidized layer on the nickel anode has a high content of nickel oxide, it has a higher electric conductivity and a higher resistance to corrosion. 4 Although a LiNiO 2 -coated Ni sheet anode prepared by atmospheric plasma spraying technique has almost same current efficiency for NF 3 formation as that on the Ni sheet anode and a relatively small anode consumption, the LiNiO 2 layer having the thickness of 20 to 50 m is dissolved during electrolysis for only 120 h, so that the lifetime of the LiNiO 2 layer in a dehydrated melt of NH 4 F•2HF may be insufficient. 5 Hence, a Ni-NiO 1ϩx (0 Ϲ x Ͻ 0.5) composite was prepared from mixture of Ni and LiNiO 2 or NiO powders by hot isostatic pressing ͑HIP͒.This paper deals with the effect of the content of nickel oxide in the composite on the current efficiency for NF 3 formation and the anode consumption. ExperimentalA mixture of LiNiO 2 ͑particle size of 1 to 3.3 m͒ and Ni ͑purity of 99.9%, particle size of 74 m͒ powders and that of NiO ͑purity of 97.0%, particle size of 1 m͒ and Ni ͑purity of...

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Section: Methodsmentioning

confidence: 99%

Preparation of a Nickel-Nickel Oxide Composite by Hot Isostatic Pressing and Its Application for Anodes Used in Electrolytic Production of Nitrogen Trifluoride

Tasaka

Suzuki

Oshida

et al. 2003

J. Electrochem. Soc.

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“…The peaks are expected to correspond to fluorine: Na 3 NiF 6 and NiF 2 appear respectively at 688.5 and 685.0 eV. 17 The peaks at 687.0 and 683.5 eV might correspond to intermediate compounds such as some oxyfluorides containing Ni 3+ and/or Ni 2+ . Products on the surface-fluorinated Ni(OH) 2 are expected to consist of fluorine-containing compounds of several kinds.…”

Section: Charge-discharge Testmentioning

confidence: 99%

Preparation of LiNiO<sub>2</sub> Using Fluorine-modified NiO and Its Charge-discharge Properties

et al. 2021

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A Ni(OH) 2 surface was fluorinated at 25°C using F 2 gas for 1 h under absolute pressure of 6.67 kPa. Some fluorides and oxyfluorides were detected only on the Ni(OH) 2 particle surface, although most Ni(OH) 2 remained inside of the particles. Fluorine-introduced NiO (NiO(F)) was obtained by heating the surface-fluorinated Ni(OH) 2 . After sintering at 750°C for 6 h, the NiO(F) crystal size and surface area were, respectively, 0.6 times smaller and 4.7 times larger than those of NiO obtained from untreated Ni(OH) 2 . LiNiO 2 samples were prepared via reaction between NiO(F) and Li 2 CO 3 at 700°C for 20 h and 30 h, respectively (LiNiO 2 (20 h, F) and LiNiO 2 (30 h, F)). The density of LiNiO 2 (30 h, F) was 4.697, which was larger than the 4.556 of LiNiO 2 prepared from NiO and Li 2 CO 3 under the same conditions. The discharge capacity of LiNiO 2 (30 h, F) was 202 mAh g −1 , whereas the LiNiO 2 prepared under the same condition from NiO and Li 2 CO 3 was 172 mAh g −1 . The discharge capacity of LiNiO 2 as a cathode of LIB might be improved by introducing fluorine to its preparation process between NiO and Li 2 CO 3 .

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“…The effect of other alkali metal fluorides [67,68] and trace level impurities like Ni 2+ and Fe 3+ species, which may be generated during electrolysis [69], on the overall efficiency of NF 3 production was also evaluated. Trace level water was also found to influence the composition of oxyfluoride films on nickel and the current efficiency of NF 3 production [70].…”

Section: Molten Fluoride Mediamentioning

confidence: 99%

Electrochemistry of metals and semiconductors in fluoride media

Noel

Suryanarayanan

2005

J Appl Electrochem

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The electrochemical surface transformations and diverse applications of a variety of metals and semiconductors in a wide range of fluoride media such as aqueous, non-aqueous media, liquid HF media, room temperature fluoride melts and molten fluoride media with a melting range covering 50-1000°C are reviewed. Nickel shows excellent corrosion resistance in the absence of water. The anodic performance of this metal in electrochemical perfluorination and NF 3 production is discussed. Compact carbon materials serve as anodes in fluorine generators. In high temperature melts, they perform as consumable anodes. Graphitic carbon undergoes intercalation/ de-intercalation process and related battery applications. Cu/CuF 2 couple is a good reference electrode. Pt and vitreous carbon materials are the inert electrodes of choice for electro analytical applications. Electrodeposition of Lithium as a non-dendritic uniform phase is important in Lithium metal based secondary batteries. High temperature fluoride melts are used in electro-deposition of valve metals such as Nb, Ta, and Ti. The stability and decomposition of fluoride complexes in these media are of interest.

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Effect of metal fluorides in the electrolyte on the electrolytic production of NF3

Cited by 18 publications

References 5 publications

Preparation of a Nickel-Nickel Oxide Composite by Hot Isostatic Pressing and Its Application for Anodes Used in Electrolytic Production of Nitrogen Trifluoride

Preparation of a Nickel-Nickel Oxide Composite by Hot Isostatic Pressing and Its Application for Anodes Used in Electrolytic Production of Nitrogen Trifluoride

Preparation of LiNiO<sub>2</sub> Using Fluorine-modified NiO and Its Charge-discharge Properties

Electrochemistry of metals and semiconductors in fluoride media

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