Details
| Original language | English |
|---|---|
| Article number | 18 |
| Journal | Physics and chemistry of minerals |
| Volume | 50 |
| Issue number | 3 |
| Publication status | Published - 23 Jun 2023 |
Abstract
In the first two papers of this series [Behrens, Phys Chem Minerals 48:8, 2021a; Behrens, Phys Chem Minerals 48:27, 2021b], incorporation of hydrogen in the feldspar structure, partitioning of hydrogen between feldspars and gases/fluids and self-diffusion of hydrogen in feldspars have been discussed, with particular focus on sanidine. Here, the results of reactions between sanidine containing strongly bonded hydrogen defects and (Na,K)Cl are presented. Experiments were performed at ambient pressure at temperatures of 605–1000 °C, and hydrogen profiles were measured by IR microspectroscopy. Profiles can be interpreted by an incomplete dehydrogenation at the crystal surface or a strong concentration dependence of hydrogen diffusivity. Both are consistent with hydrogen located on interstitial sites and difficult to substitute by the larger alkali ions. Chemical diffusivities of hydrogen derived from fitting of the profiles or Boltzmann–Matano analysis are similar to self-diffusivities determined by D/H exchange experiments. Activation energies are also comparable. Comparison to sodium and potassium diffusion data for sanidine (Wilangowski et al. in Defect Diffus Forum 363: 79–84, 2015; Hergemöller et al. in Phys Chem Minerals 44:345–351, 2017) supports a mechanism of proton diffusion charge-compensated by Na+ diffusion for hydrogen removal in the sanidines under dry conditions.
Keywords
- Dehydrogenation, Diffusion, Hydrogen defects, Igneous feldspar, Infrared spectroscopy
ASJC Scopus subject areas
- Materials Science(all)
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Physics and chemistry of minerals, Vol. 50, No. 3, 18, 23.06.2023.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Hydrogen defects in feldspars
T2 - alkali-supported dehydrogenation of sanidine
AU - Behrens, Harald
N1 - Funding Information: My special thanks go to Otto Dietrich for the excellent preparation of feldspar sections. I thank Fabian Hergemöller for stimulating thoughts on proton and alkali diffusion. Particular thanks to Andreas Kronenberg, Sylvie Demouchy and an anonymous third reviewer for fruitful comments. The research was supported by the researcher unit FOR2881 of the German Science foundation (DFG).
PY - 2023/6/23
Y1 - 2023/6/23
N2 - In the first two papers of this series [Behrens, Phys Chem Minerals 48:8, 2021a; Behrens, Phys Chem Minerals 48:27, 2021b], incorporation of hydrogen in the feldspar structure, partitioning of hydrogen between feldspars and gases/fluids and self-diffusion of hydrogen in feldspars have been discussed, with particular focus on sanidine. Here, the results of reactions between sanidine containing strongly bonded hydrogen defects and (Na,K)Cl are presented. Experiments were performed at ambient pressure at temperatures of 605–1000 °C, and hydrogen profiles were measured by IR microspectroscopy. Profiles can be interpreted by an incomplete dehydrogenation at the crystal surface or a strong concentration dependence of hydrogen diffusivity. Both are consistent with hydrogen located on interstitial sites and difficult to substitute by the larger alkali ions. Chemical diffusivities of hydrogen derived from fitting of the profiles or Boltzmann–Matano analysis are similar to self-diffusivities determined by D/H exchange experiments. Activation energies are also comparable. Comparison to sodium and potassium diffusion data for sanidine (Wilangowski et al. in Defect Diffus Forum 363: 79–84, 2015; Hergemöller et al. in Phys Chem Minerals 44:345–351, 2017) supports a mechanism of proton diffusion charge-compensated by Na+ diffusion for hydrogen removal in the sanidines under dry conditions.
AB - In the first two papers of this series [Behrens, Phys Chem Minerals 48:8, 2021a; Behrens, Phys Chem Minerals 48:27, 2021b], incorporation of hydrogen in the feldspar structure, partitioning of hydrogen between feldspars and gases/fluids and self-diffusion of hydrogen in feldspars have been discussed, with particular focus on sanidine. Here, the results of reactions between sanidine containing strongly bonded hydrogen defects and (Na,K)Cl are presented. Experiments were performed at ambient pressure at temperatures of 605–1000 °C, and hydrogen profiles were measured by IR microspectroscopy. Profiles can be interpreted by an incomplete dehydrogenation at the crystal surface or a strong concentration dependence of hydrogen diffusivity. Both are consistent with hydrogen located on interstitial sites and difficult to substitute by the larger alkali ions. Chemical diffusivities of hydrogen derived from fitting of the profiles or Boltzmann–Matano analysis are similar to self-diffusivities determined by D/H exchange experiments. Activation energies are also comparable. Comparison to sodium and potassium diffusion data for sanidine (Wilangowski et al. in Defect Diffus Forum 363: 79–84, 2015; Hergemöller et al. in Phys Chem Minerals 44:345–351, 2017) supports a mechanism of proton diffusion charge-compensated by Na+ diffusion for hydrogen removal in the sanidines under dry conditions.
KW - Dehydrogenation
KW - Diffusion
KW - Hydrogen defects
KW - Igneous feldspar
KW - Infrared spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85163034457&partnerID=8YFLogxK
U2 - 10.1007/s00269-023-01242-9
DO - 10.1007/s00269-023-01242-9
M3 - Article
AN - SCOPUS:85163034457
VL - 50
JO - Physics and chemistry of minerals
JF - Physics and chemistry of minerals
SN - 0342-1791
IS - 3
M1 - 18
ER -