26Al tracer diffusion in titanium doped single crystalline α-Al2O3

Fielitz, P.; Borchardt, Günter; Ganschow, Steffen; Bertram, R.; Markwitz, A.

doi:10.1016/j.ssi.2008.03.007

Cited by 33 publications

(45 citation statements)

References 16 publications

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“…Heating/cooling rates to the target anneal temperature were sufficiently high such that the effective additional annealing times are calculated to be negligible (estimates provided in Table S1) 53 . Samples were hydrated in isotopically normal water at run conditions, quenched and then annealed at the same run conditions in the presence of deuterated water allowing deuterium ( 2 H) to diffusively exchange with hydrogen ( 1 H).…”

Section: Methodsmentioning

confidence: 99%

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

Novella

Jacobsen

Weber

et al. 2017

Sci Rep

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Nominally anhydrous minerals formed deep in the mantle and transported to the Earth’s surface contain tens to hundreds of ppm wt H2O, providing evidence for the presence of dissolved water in the Earth’s interior. Even at these low concentrations, H2O greatly affects the physico-chemical properties of mantle materials, governing planetary dynamics and evolution. The diffusion of hydrogen (H) controls the transport of H2O in the Earth’s upper mantle, but is not fully understood for olivine ((Mg, Fe)2SiO4) the most abundant mineral in this region. Here we present new hydrogen self-diffusion coefficients in natural olivine single crystals that were determined at upper mantle conditions (2 GPa and 750–900 °C). Hydrogen self-diffusion is highly anisotropic, with values at 900 °C of 10−10.9, 10−12.8 and 10−11.9 m2/s along [100], [010] and [001] directions, respectively. Combined with the Nernst-Einstein relation, these diffusion results constrain the contribution of H to the electrical conductivity of olivine to be σH = 102.12S/m·CH2O·exp−187kJ/mol/(RT). Comparisons between the model presented in this study and magnetotelluric measurements suggest that plausible H2O concentrations in the upper mantle (≤250 ppm wt) can account for high electrical conductivity values (10−2–10−1 S/m) observed in the asthenosphere.

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Section: Methodsmentioning

confidence: 99%

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

Novella

Jacobsen

Weber

et al. 2017

Sci Rep

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“…Fielitz et al 61 performed simultaneous 18 O and 26 Al tracer diffusion measurements in the temperature range 1230-1500 • C on Ti-doped Al 2 O 3 single crystals and demonstrated that D Al is orders of magnitude higher than D oxy . Extrapolation of their data to the temperature range used by Paladino …”

Section: Note Added In Proofmentioning

confidence: 99%

Oxygen and aluminum diffusion in α-Al2O3: How much do we really understand?

Heuer

2008

Journal of the European Ceramic Society

252

142

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“…While O transport is readily studied by 18 O tracers, it is much more difficult to study Al transport. There is only one stable isotope, and its radioactive isotope, Al 26 , has a lifetime of only about 25 h. The diffusivity of Al 26 in alumina was investigated by Fielitz et al [16]. However, in order to study outward diffusion, the isotope must be in the alloy or in the oxide beneath a previously formed oxide.…”

Section: Introductionmentioning

confidence: 99%

Grain Boundary Chemistry and Transport Through Alumina Scales on NiAl Alloys

et al. 2017

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It is widely accepted that the growth of protective a-Al 2 O 3 scales on Nibased alloys is governed by the inward diffusion of oxygen through the oxide grain boundaries (GB). However, there is also some outward diffusion of metal ions to the surface, but it is difficult to quantify. In this work we apply atomic force microscopy, scanning electron microscopy and transmission electron microscopy to investigate the outward flux of Al, which manifests as the growth of small ridges along the alumina GBs after the removal of the outermost oxide layer by mechanical polishing or focused ion beam techniques followed by additional oxidation. As a model alumina-former, NiAl with Hf and Zr additions was investigated. In comparison to Zr, Hf was found to reduce the outward Al diffusion. This outward diffusion was six orders of magnitude smaller than the O inward diffusion.

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26Al tracer diffusion in titanium doped single crystalline α-Al2O3

Cited by 33 publications

References 16 publications

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

Hydrogen self-diffusion in single crystal olivine and electrical conductivity of the Earth’s mantle

Oxygen and aluminum diffusion in α-Al2O3: How much do we really understand?

Grain Boundary Chemistry and Transport Through Alumina Scales on NiAl Alloys

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