Document Type
Article
Publication Date
4-5-2005
Journal or Book Title
Chemistry of Materials
Volume
17
Issue
7
First Page
1728
Last Page
1735
DOI
10.1021/cm0488581
Abstract
The synthesis, structure, and nonhumidified proton conductivity of the hydrated alkali thio-hydroxogermanates, denoted as MxGeSx(OH)4-x·yH2O (1 ≤ x ≤ 4, 0 < y < 8) for M = Na, K, Rb, and Cs, are reported. These materials are generally X-ray amorphous when produced by a low-temperature (75 °C) aqueous solution evaporation−precipitation route. Raman and IR spectroscopies indicate mixed chalcogenide germanium central anions with distinct asymmetric Ge−O and symmetric Ge−S stretching modes observable around 820−754 and 500−325 cm-1, respectively. These thio-oxoanions possess a combination of thermally stable hydroxyl groups and hydrophilic alkali associated with the nonbridging sulfurs. Alternating current impendence measurements performed under anhydrous conditions on low-pressure sealed pellets reveal fast ionic conductivity, 10-3−10-2 S/cm, for typical temperatures between 100 and 275 °C. The observed falloff in conductivity at higher temperatures is consistent with the appearance of endothermic transitions in differential scanning calorimetry measurements of hermetically sealed samples, presumably from the “boiling” or sublimation of a crystalline water sublattice. Corresponding onset temperatures were observed between 150 and 275 °C and dependent on the alkali and composition. Under dry atmosphere conditions, thermogravimetric analysis mass loss measurements indicate continuous mass loss above the preparation temperature of 75 °C.
Copyright Owner
American Chemical Society
Copyright Date
2005
Language
en
File Format
application/pdf
Recommended Citation
Poling, Steven A.; Nelson, Carly R.; and Martin, Steve W., "Synthesis and Characterization of Amorphous Hydrated Alkali Thio-Hydroxogermanates" (2005). Materials Science and Engineering Publications. 51.
https://lib.dr.iastate.edu/mse_pubs/51
Comments
Reprinted with permission from Chemistry of Materials 17 (2005): 1728–1735, doi:10.1021/cm0488581. Copyright 2005 American Chemical Society.