Corrosion Behavior of Tantalum and Niobium in Hydrobromic Acid Solutions (II) on Passive Films and Hydrogen Absorption

Uehara, I.; Sakai, T.; Ishikawa, H.; Takenaka, Hidetsugu

doi:10.5006/1.3577870

Cited by 11 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“… 39 Among transition metals, group VB metals are good hydrogen storage substrates. 40 − 42 Therefore, the more aligned and consistent CNT growth on Nb and Ta might be due to hydrogen release that helps maintain the activation of iron catalysts.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Another possible reason for the varied CNT morphology on different substrates is the amount of hydrogen absorbed in the metal substrates, which could affect the microstructure and mechanical properties of the resulting CNT gowth . Among transition metals, group VB metals are good hydrogen storage substrates. − Therefore, the more aligned and consistent CNT growth on Nb and Ta might be due to hydrogen release that helps maintain the activation of iron catalysts.…”

Section: Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine

et al. 2015

View full text Add to dashboard Cite

Microelectrodes modified with carbon nanotubes (CNTs) are useful for the detection of neurotransmitters because the CNTs enhance sensitivity and have electrocatalytic effects. CNTs can be grown on carbon fiber microelectrodes (CFMEs) but the intrinsic electrochemical activity of carbon fibers makes evaluating the effect of CNT enhancement difficult. Metal wires are highly conductive and many metals have no intrinsic electrochemical activity for dopamine, so we investigated CNTs grown on metal wires as microelectrodes for neurotransmitter detection. In this work, we successfully grew CNTs on niobium substrates for the first time. Instead of planar metal surfaces, metal wires with a diameter of only 25 μm were used as CNT substrates; these have potential in tissue applications due to their minimal tissue damage and high spatial resolution. Scanning electron microscopy shows that aligned CNTs are grown on metal wires after chemical vapor deposition. By use of fast-scan cyclic voltammetry, CNT-coated niobium (CNT-Nb) microelectrodes exhibit higher sensitivity and lower ΔEp value compared to CNTs grown on carbon fibers or other metal wires. The limit of detection for dopamine at CNT-Nb microelectrodes is 11 ± 1 nM, which is approximately 2-fold lower than that of bare CFMEs. Adsorption processes were modeled with a Langmuir isotherm, and detection of other neurochemicals was also characterized, including ascorbic acid, 3,4-dihydroxyphenylacetic acid, serotonin, adenosine, and histamine. CNT-Nb microelectrodes were used to monitor stimulated dopamine release in anesthetized rats with high sensitivity. This study demonstrates that CNT-grown metal microelectrodes, especially CNTs grown on Nb microelectrodes, are useful for monitoring neurotransmitters.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine

et al. 2015

View full text Add to dashboard Cite

show abstract

“…In the present situation, parabolic nature of the film growth hints that diffusion of either Ta ions or positively charged oxygen vacancies was responsible for the growth of the oxide layer. The tantalum oxide film forms on Ta surface as per the following reaction in aqueous solution as suggested by previous researchers 3, [19][20][21] 2Ta…”

Section: Resultsmentioning

confidence: 96%

Effect of pH and H[sub 2]O[sub 2] on Ta Chemical Mechanical Planarization

Kuiry

Seal

Fei

et al. 2003

J. Electrochem. Soc.

View full text Add to dashboard Cite

Tantalum is used as a diffusion barrier and adhesion promoter layer between the dielectric material and copper interconnects. The present study was intended to investigate the effect of oxidizer and solution pH on chemical mechanical planarization of tantalum. High purity Ta disks were used to study the dissolution and oxidation kinetics under static and dynamic conditions using various solutions in acidic and alkaline pH regimes. The electrochemical measurements during dynamic polishing of a Ta disk were carried out using slurries containing silica and alumina particles with hydrogen peroxide at various pH levels. The affected surface layers of the statically etched Ta disk were investigated using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and secondary ion mass spectrometry (SIMS). Ta metal was observed to oxidize in aqueous solutions at pH 2, 4, and 12 in absence of H2O2. The oxidation process follows the parabolic kinetic law and oxidation rate was observed to be higher in an alkaline region than in an acidic region. In the presence of H2O2, however, Ta dissolved in the alkaline region. The dissolution was found to be greater at pH 12 mainly because of enhanced dissociation of H2O2 in alkaline region. At pH 2, on the contrary, mass gain was observed probably due to an increase in OH− content on the top of Ta oxide formed on the surface as confirmed by XPS and SIMS depth profile studies. XPS study revealed that the oxidation of tantalum takes place at a rapid rate and forms soluble oxotantalate and hydroxotantalate in solution at pH 12 in the presence of hydrogen peroxide. AFM study validates both the XPS and the SIMS results, indicating formation of a thin impervious oxide layer on Ta in a solution at pH 2 with 5% H2O2, and a porous layer was formed on Ta in solution with 5% H2O2 at pH 12. Consequently, the dissolution rate in alkaline region was enhanced which was confirmed by dynamic removal rate measurements, electrochemistry, and XPS studies. © 2002 The Electrochemical Society. All rights reserved.

show abstract

“…Likewise, the corrosion behavior of tantalum and niobium was studied in concentrated HBr solution at 25 and 100 C and, under oxidizing conditions (with added bromine) or reducing conditions (with bubbled hydrogen gas). 30 Tantalum was found to passivate under all conditions studied while niobium corroded slowly at 100 C with pits of around 5 mm evident. Under reducing conditions, niobium gradually began to corrode actively with hydrogen evolution, while under oxidizing conditions it passivated.…”

Section: Passivity Corrosion and Localized Corrosionmentioning

confidence: 98%

Corrosion of Tantalum and Niobium and their Alloys

Lyon¹

2010

Shreir's Corrosion

View full text Add to dashboard Cite

Corrosion Behavior of Tantalum and Niobium in Hydrobromic Acid Solutions (II) on Passive Films and Hydrogen Absorption

Cited by 11 publications

References 0 publications

Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine

Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine

Effect of pH and H[sub 2]O[sub 2] on Ta Chemical Mechanical Planarization

Corrosion of Tantalum and Niobium and their Alloys

Contact Info

Product

Resources

About