Details
| Original language | English |
|---|---|
| Article number | 194505 |
| Journal | Journal of Chemical Physics |
| Volume | 134 |
| Issue number | 19 |
| Publication status | Published - 21 May 2011 |
Abstract
Hydrous silicate glasses with compositions along the join diopside-anorthite (An, CaAl2Si2O8)-(Di, CaMgSi2O6) containing up to 3 % wt. H2O were synthesized at temperatures 1523-1723 K and pressures of 200 MPa in an internally heated gas pressure vessel. The water content of the glasses was analyzed by Karl-Fischer titration. Infrared microspectroscopy was used to test the homogeneity of the water distribution and to measure the concentrations of OH groups and H2O molecules before and after conductivity measurements. The electrical conductivity was measured by impedance spectroscopy at temperature up to 685 K. A positive correlation between water content and conductivity was observed for An100 from 0 to 1.8 wt. % H 2O, for An50Di50 (in mol. %) from 1.5 to 2.8 wt. % H2O, and for Di100 from 0 to 1.2 wt. % H 2O. At same water content of ∼1.2 wt. , the conductivity was three orders of magnitude higher in Di100 than in the other two glasses, emphasizing the importance of non-bridging oxygens on the transport of hydrous charge carriers. Consistent with findings in literature, we conclude that protons are the predominant mobile charge carriers in alkali-free hydrous silicate glasses. Conductivity data were evaluated in terms of proton diffusivity by the Nernst-Einstein equation. The obtained diffusion coefficients range from 10-17 m2s for An50Di50 with 1.50 wt. % of H2O at 596 K to 10-12 m2s for An50Di50 with 2.77 wt. % of H2O at 685 K.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- General Physics and Astronomy
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: Journal of Chemical Physics, Vol. 134, No. 19, 194505, 21.05.2011.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Proton conduction in hydrous glasses of the join CaAl2Si 2O8-CaMgSi2O6
T2 - An impedance and infrared spectroscopic study
AU - Fanara, Sara
AU - Behrens, Harald
N1 - Funding Information: Sara Fanara acknowledges the Ministry of Science and Culture, Land Niedersachsen, for its support. The authors appreciate the help received from Oliver Beerman during hydrous glass syntheses and from Elke Schlechter during impedance measurements. The authors also thank Otto Diedrich for sample preparation.
PY - 2011/5/21
Y1 - 2011/5/21
N2 - Hydrous silicate glasses with compositions along the join diopside-anorthite (An, CaAl2Si2O8)-(Di, CaMgSi2O6) containing up to 3 % wt. H2O were synthesized at temperatures 1523-1723 K and pressures of 200 MPa in an internally heated gas pressure vessel. The water content of the glasses was analyzed by Karl-Fischer titration. Infrared microspectroscopy was used to test the homogeneity of the water distribution and to measure the concentrations of OH groups and H2O molecules before and after conductivity measurements. The electrical conductivity was measured by impedance spectroscopy at temperature up to 685 K. A positive correlation between water content and conductivity was observed for An100 from 0 to 1.8 wt. % H 2O, for An50Di50 (in mol. %) from 1.5 to 2.8 wt. % H2O, and for Di100 from 0 to 1.2 wt. % H 2O. At same water content of ∼1.2 wt. , the conductivity was three orders of magnitude higher in Di100 than in the other two glasses, emphasizing the importance of non-bridging oxygens on the transport of hydrous charge carriers. Consistent with findings in literature, we conclude that protons are the predominant mobile charge carriers in alkali-free hydrous silicate glasses. Conductivity data were evaluated in terms of proton diffusivity by the Nernst-Einstein equation. The obtained diffusion coefficients range from 10-17 m2s for An50Di50 with 1.50 wt. % of H2O at 596 K to 10-12 m2s for An50Di50 with 2.77 wt. % of H2O at 685 K.
AB - Hydrous silicate glasses with compositions along the join diopside-anorthite (An, CaAl2Si2O8)-(Di, CaMgSi2O6) containing up to 3 % wt. H2O were synthesized at temperatures 1523-1723 K and pressures of 200 MPa in an internally heated gas pressure vessel. The water content of the glasses was analyzed by Karl-Fischer titration. Infrared microspectroscopy was used to test the homogeneity of the water distribution and to measure the concentrations of OH groups and H2O molecules before and after conductivity measurements. The electrical conductivity was measured by impedance spectroscopy at temperature up to 685 K. A positive correlation between water content and conductivity was observed for An100 from 0 to 1.8 wt. % H 2O, for An50Di50 (in mol. %) from 1.5 to 2.8 wt. % H2O, and for Di100 from 0 to 1.2 wt. % H 2O. At same water content of ∼1.2 wt. , the conductivity was three orders of magnitude higher in Di100 than in the other two glasses, emphasizing the importance of non-bridging oxygens on the transport of hydrous charge carriers. Consistent with findings in literature, we conclude that protons are the predominant mobile charge carriers in alkali-free hydrous silicate glasses. Conductivity data were evaluated in terms of proton diffusivity by the Nernst-Einstein equation. The obtained diffusion coefficients range from 10-17 m2s for An50Di50 with 1.50 wt. % of H2O at 596 K to 10-12 m2s for An50Di50 with 2.77 wt. % of H2O at 685 K.
UR - http://www.scopus.com/inward/record.url?scp=79957607954&partnerID=8YFLogxK
U2 - 10.1063/1.3589898
DO - 10.1063/1.3589898
M3 - Article
AN - SCOPUS:79957607954
VL - 134
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 19
M1 - 194505
ER -