Formation process of zirconia nanotubes and porous structures and model of oxygen bubble growth

Observation of Oxygen Bubble Growth near Anode Catalyst Electrode in PEM Water Electrolyzer

ECS Meeting Abstracts ◽

10.1149/ma2021-02411230mtgabs ◽

2021 ◽

Vol MA2021-02 (41) ◽

pp. 1230-1230

Author(s):

Konosuke Watanabe ◽

Kohei Wakuda ◽

Kodai Wani ◽

Takuto Araki ◽

Kensaku Nagasawa ◽

...

Keyword(s):

Bubble Growth ◽

Anode Catalyst ◽

Oxygen Bubble ◽

Pem Water Electrolyzer ◽

Catalyst Electrode

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Diffusion-Controlled Growth of Oxygen Bubble Evolved from Nanorod-Array TiO2Photoelectrode

Advances in Condensed Matter Physics ◽

10.1155/2014/970891 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 5

Author(s):

Xiaowei Hu ◽

Yechun Wang ◽

Liejin Guo ◽

Zhenshan Cao

Keyword(s):

Bubble Growth ◽

Aqueous Electrolyte ◽

Experimental Studies ◽

Nanorod Array ◽

Diffusion Controlled ◽

Oxygen Bubble ◽

Starting Point ◽

Solid Liquid Interface ◽

Solid Liquid ◽

Interface Movement

Nanorod-array structure gains its popularity in photoelectrode design for water splitting. However, the structure’s effects on solid-liquid interface interaction and reaction product transportation still remain unsolved. Gas bubble generally evolved from photoelectrodes, which provides a starting point for the problem-solving. Based on this, investigations on the gas-evolving photoelectrode are carried out in this paper. By experimental studies of wettability on the photoelectrode nanorod-array surface and oxygen bubble growth from anode, we analyzed the interaction affecting the gas-solid-liquid contact behaviors and product transportation mechanism, which is controlled by diffusion due to the concentration gradient of dissolved gases in the aqueous electrolyte and the microconvection caused by the bubble interface movement. In the end, based on the bubble growth characteristics ofRB(t)~t0.5in the experiment, a model describing the product transport mechanism was presented.

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Pore Formation and Propagation Mechanism in Porus Silicon

MRS Proceedings ◽

10.1557/proc-256-3 ◽

1991 ◽

Vol 256 ◽

Cited By ~ 24

Author(s):

V. Lehmann ◽

H. Cerva ◽

U. Gosele

Keyword(s):

Porous Structure ◽

Space Charge ◽

Space Charge Region ◽

Formation Process ◽

Quantum Confinement ◽

Pore Formation ◽

Propagation Mechanism ◽

Porous Structures

ABSTRACTThis paper presents a model of the microporous silicon formation process which is based on hole depletion due to quantum confinement in the porous structure. This model is compared with the formation of larger porous structures (meso-, macroporous) where hole depletion is generated by a space charge region.

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A review of late-stage tungsten fuzz growth

Tungsten ◽

10.1007/s42864-021-00133-2 ◽

2022 ◽

Author(s):

Jacob A. R. Wright

Keyword(s):

Formation Mechanism ◽

Formation Process ◽

Late Stage ◽

Bubble Growth ◽

Fusion Reactor ◽

Adatom Diffusion ◽

Successful Design ◽

Tungsten Surface ◽

Rate Limiting ◽

Tungsten Catalysts

AbstractTungsten will be used as the plasma-facing divertor material in the International Thermonuclear Experimental Reactor (ITER) fusion reactor. Under high temperatures and high ion fluxes, a ‘fuzz’ nanostructure forms on the tungsten surface with dramatically different properties and could contaminate the plasma. Although simulations and experimental observations have provided understanding of the initial fuzz formation process, there is debate over whether tungsten or helium migration is rate-limiting during late-stage growth, and the mechanisms by which tungsten and helium migrations occur. Here, the proposed mechanisms are considered in turn. It is concluded that tungsten migration occurs by adatom diffusion along the fuzz surface. Continual helium migration through the porous fuzz to the tungsten bulk is also required for fuzz growth, for continued bubble growth and rupture. Helium likely migrates due to ballistic penetration, although diffusion may contribute. It is difficult to determine the limiting process, which may switch from helium penetration to tungsten adatom diffusion above a threshold flux. Areas for further research to clarify the mechanisms are then considered. A greater understanding of the fuzz formation mechanism is key to the successful design of plasma-facing tungsten components, and may have applications in forming porous tungsten catalysts.

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Direct observations of radiation-enhanced transformations in glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075543 ◽

1983 ◽

Vol 41 ◽

pp. 354-355

Author(s):

J. F. DeNatale ◽

D. G. Howitt

Keyword(s):

Glass Matrix ◽

Diffusion Mechanism ◽

Bubble Formation ◽

Silicate Glasses ◽

Phase Decomposition ◽

Direct Observations ◽

Thin Foils ◽

Oxygen Bubble ◽

Electron Energy Loss ◽

Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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Formation process of periodic non-conservative antiphase boundary structure in L-Pd5Ce

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173947 ◽

1990 ◽

Vol 48 (4) ◽

pp. 162-163

Author(s):

Masaru Itakura ◽

Noriyuki Kuwano ◽

Kensuke Oki

Keyword(s):

Formation Process ◽

Domain Size ◽

Antiphase Boundary ◽

Boundary Structure ◽

Temperature Phase ◽

Arc Melting ◽

Iced Water ◽

Antiphase Domains ◽

Low Temperature Phase ◽

Degree Of Order

The low temperature phase of Pd5Ce (L-Pd5Ce) has a one-dimensional long period superstructure (1D-LPS) derived from Ll2. The periodic antiphase boundaries (APBs) are parallel to (110) planes and have a shift vector of 1/2[110]. Hereafter, the indices are referred to the basic lattices of Ll2 As insertion of the APB causes a change in composition, such an APB is called “non-conservative”. Then, a domain size M depends upon the Ce concentration in the alloy. It was found that M increases also with temperature. The temperature dependency of M is attributed to a change of the degree of order within the antiphase domains. In this work, morphology of the non-conservative APBs is observed to clarify the formation process of the 1D-LPS.The alloy of Pd-16.7 at%Ce was prepared by arc melting in argon atmosphere. Disc specimens made from the alloy ingot were first held at 985 K for 260 ks and quenched in iced water to obtain the state of M=∞ or Ll2, followed by annealing for various lengths of time. The annealing temperature was 873 K where the equilibrium value for M is about 3 in unit of (110) lattice spacing of Ll2. Observation was carried out using microscopes JEM-2000FX, JEM-4000EX (HVEM Lab., Kyushu Univ.) and JEM-2000EX (Dept. of Mater. Sci. Tech., Kyushu Univ.).

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