Water diffusion coefficient measurements in deposited silica coatings by the substrate curvature method

Thurn, Jeremy

doi:10.1016/j.jnoncrysol.2008.09.008

Cited by 12 publications

(8 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By considering that one mole of metal reacts with q moles of water, the integration of metal dissolved at each location through the thickness of the film and over time gives the remaining thickness of metal thin films, normalized by its initial thickness h 0 as

\begin{matrix} true \\ right \frac{h}{h_{0}} \approx 1 - \frac{t}{t_{c}} \end{matrix}

where

t_{normalc} = h_{0} q ρ M_{{normalH}_{2} O} {((), \sqrt{k D} w_{0} M)}^{- 1} {prefixtanh}^{- 1} \sqrt{k h_{0}^{2} / D}

is the critical time when the thickness reaches zero, ρ is the mass density of metal, M and

M_{H_{2} normalO}

are the molar masses of metal and water, respectively. The EDR can therefore be estimated according to:

\begin{matrix} true \\ right v_{EDR} = - \frac{d h}{d t} = \sqrt{k D} \frac{w_{o} M}{q ρ M_{H_{2} normalO}} prefixtanh \sqrt{\frac{k h_{o}^{2}}{D}} \end{matrix}

Two free parameters, D and k , are allowed to vary to yield good fits to the measured resistance curves in Figure a–f, where the diffusivity D is constrained to a reasonable range (≈10 −10 −10 −17 cm 2 s −1 ), with reference to diffusivities of water in sputtered silica at RT (≈10 −11 cm 2 s −1 ) and silica glass (≈10 −16 cm 2 s −1 ), since values for the diffusivity of water in metal thin films are not generally available in the literature. The following diffusivities are obtained, D = 6 × 10 −12 cm 2 s −1 at RT and D = 1.2 × 10 −11 cm 2 s −1 at 37 °C for Mg, Mg alloys, and Zn, and D = 1 × 10 −16 cm 2 s −1 at RT and D = 2 × 10 −16 cm 2 s −1 at 37 °C for W and Mo.…”

Section: Resultsmentioning

confidence: 99%

Dissolvable Metals for Transient Electronics

Yin

Cheng²,

Mao

et al. 2013

Adv Funct Materials

417

483

View full text Add to dashboard Cite

Reactive dissolution and its effects on electrical conduction, morphological change and chemical transformation in thin fi lms of Mg, AZ31B Mg alloy, Zn, Fe, W, and Mo in de-ionized (DI) water and simulated body fl uids (Hanks' solution pH 5-8) are systematically studied, to assess the potential for use of these metals in water-soluble, that is, physically "transient", electronics. The results indicate that the electrical dissolution rates in thin fi lms can be much different that traditionally reported corrosion rates in corresponding bulk materials. Silicon metal oxide fi eld effect transistors (MOSFETs) built with these metals demonstrate feasibility for use in transient electronics.

show abstract

\begin{matrix} true \\ right \frac{h}{h_{0}} \approx 1 - \frac{t}{t_{c}} \end{matrix}

where

t_{normalc} = h_{0} q ρ M_{{normalH}_{2} O} {((), \sqrt{k D} w_{0} M)}^{- 1} {prefixtanh}^{- 1} \sqrt{k h_{0}^{2} / D}

is the critical time when the thickness reaches zero, ρ is the mass density of metal, M and

M_{H_{2} normalO}

are the molar masses of metal and water, respectively. The EDR can therefore be estimated according to:

\begin{matrix} true \\ right v_{EDR} = - \frac{d h}{d t} = \sqrt{k D} \frac{w_{o} M}{q ρ M_{H_{2} normalO}} prefixtanh \sqrt{\frac{k h_{o}^{2}}{D}} \end{matrix}

Section: Resultsmentioning

confidence: 99%

Dissolvable Metals for Transient Electronics

Yin

Cheng²,

Mao

et al. 2013

Adv Funct Materials

417

483

View full text Add to dashboard Cite

show abstract

“…The obtained broad MWDs of the polymers suggest that the silica surface provides only a limited mobility for the catalyst. The limited accessibility of the catalyst on the hydrated surface can be attributed to a reported low self-diffusion coefficient ( D water = 10 –12 –10 –17 cm 2 /s) of water on the silica surface. − The self-diffusion coefficient of water on the silica surface is substantially lower than in the Na-clay surface and the bulk water ( D = 2.25 × 10 –5 cm 2 /s) (Table ). , This will decrease the mobility of the catalyst suspended in the hydrated layer and will reduce the deactivation rate of the growing radicals in silica supported catalyst system. Although, the average particle size of silica is much bigger than the clay in this study, the polymerization results are not influenced by the surface area as the nanosilica support also produced PBnMA with broad MWD (Table , run 7, Figure c).…”

Section: Resultsmentioning

confidence: 99%

Hydration Mediation in Supported Aqueous-Phase Catalysis for Atom Transfer Radical Polymerization

Aggarwal

Baskaran

2011

Macromolecules

View full text Add to dashboard Cite

Hydrated sodium montmorillonite (Na-clay) and silica gel are used as solid supports for atom transfer radical polymerization (ATRP) of benzyl methacrylate and methyl methacrylate. The catalyst complexes of CuBr2 and CuBr with N,N,N′,N′,N″-pentamethyldiethylenetriamine, which are physically adsorbed on Na-clay and silica gel, are efficiently retained by the solid supports via small amounts of hydration. The supported aqueous-phase catalysis (SAPC) over Na-clay and silica produces catalyst-free polymers for activator generated electron transfer ATRP and conventional ATRP processes. The kinetics for the catalyst supported Na-clay and silica systems show that the polymerization proceeded only in the presence of hydrated catalyst support and ceased when the polymerization solution was separated from the hydrated catalyst support. In the case of Na-clay SAPC, the polymerization follows a linear first-order time–conversion plot and produces polymers with moderately narrow molecular weight distribution (MWD, M w/M n ≤ 1.30). However, for silica SAPC the first-order time–conversion plot is curved, indicating that the polymerization proceeds with termination and polymers exhibited broad MWD (M w/M n > 1.50). The poor performance of silica SAPC is attributed to the inefficient mobility of the catalyst and the nature of hydrogen bonding of the water molecules on its surface. The bilogarithmic plot of apparent rate constant k app vs [I]0 in SAPC for ATRP indicates a zero order, suggesting that the polymerization is independent of the bulk initiator concentration, and the propagation is confined to the hydrated interface between the solid support and the organic phase.

show abstract

“…At the heart of this study is an experiment in which water is diffused into one side of thin vitreous silica disks. This technique has been used earlier to determine the volume change caused by the penetration of water into silica coatings on silicon wafers . The consequent volume expansion in the coating resulted in a bending of the disks .…”

Section: Methodsmentioning

confidence: 99%

Volume Expansion Caused by Water Penetration into Silica Glass

Wiederhorn

LaVan

et al. 2014

J. Am. Ceram. Soc.

View full text Add to dashboard Cite

By measuring the curvature of thin disks of vitreous silica that have been penetrated by water from one side only, we determined the volume expansion of the silica and the effect of this volume expansion on its strength. We found that the waterstrengthening process depended on crack-size, temperature, and the amount of swelling of the silica. We also evaluated the diffusivity of water in vitreous silica, using the swelling stresses as the diffusion metric. Diffusivity values, so obtained, are close to the accepted values for the diffusion of water in vitreous silica, as is the activation energy for the diffusion process. Our data suggest that swelling and the consequent bending of the disks is caused by silanol group formation in the silica structure; molecular water plays little role in the swelling process.Si-O-Si þH 2 O $ 2ð SiOHÞ:(1)At high temperatures, > 500°C, the relative amounts of H 2 O and SiOH are given by the equilibrium constant K w0 :where [H 2 O] is the concentration of water and [SiOH] is the concentration of the silanol groups in the glass, in units of moles per volume of glass (M/m 3 ). Equation 2 is based on the assumption that the silanol groups are unassociated, which is to say the groups are far enough apart to act as independent molecular entities. At lower temperatures, T < 250°C, 16 the silanol groups are usually associated so that the two silanol groups are sufficiently close together that they can behave as a single chemical entity. Equation 2 then takes the following form:as shown by Oehler and Tomozawa 16 in a study of the diffusion of water into silica glass. These authors measured the J. Mauro-contributing editor Manuscript No. 35176.

show abstract

Water diffusion coefficient measurements in deposited silica coatings by the substrate curvature method

Cited by 12 publications

References 15 publications

Dissolvable Metals for Transient Electronics

Dissolvable Metals for Transient Electronics

Hydration Mediation in Supported Aqueous-Phase Catalysis for Atom Transfer Radical Polymerization

Volume Expansion Caused by Water Penetration into Silica Glass

Contact Info

Product

Resources

About