Details
| Original language | English |
|---|---|
| Pages (from-to) | 2173-2178 |
| Number of pages | 6 |
| Journal | Materials research bulletin |
| Volume | 46 |
| Issue number | 11 |
| Early online date | 6 Jan 2011 |
| Publication status | Published - Nov 2011 |
Abstract
Sodalites Na8[AlSiO4]6(BH 4)1.8(H3O2)0.2 and Na8[AlSiO4]6(BH4)(H 3O2)0.5(CO3)0.25(H 2O) were examined to characterize the influence of the mixed cage fillings and the surroundings on the thermal behaviour of enclathrated BH 4- and the stability of the alumosilicate framework. The samples were investigated in a NaCl matrix during temperature dependent IR-measurements (TIR) and by thermal analysis in inert atmosphere (helium) and in synthetic air. The thermal products were further characterized by XRD and SEM/EDS. It could be shown that the extent of the BH4- decomposition strongly depends on the cage-fillings of the individual sodalite phase and on the environmental experimental conditions. At low to medium temperatures hydrolysis of BH4- by water molecules from decomposition of H3O2- and H 2O/CO32- templates leads to B(OH) 4-/BH3OH- and via subsequent dehydration to BO(OH)2- and finally BO2 -. At elevated temperatures direct oxidation of BH4 - to BO2- occurs inside the sodalite cages. Further heating results in sodalite framework destruction and finally formation of nepheline with some boron in its structure besides some unknown polymeric borates outside the alumosilicate phase. Framework stability of the sodalites was found to decrease in the direction → heating in NaCl → heating in He-atmosphere → heating in air.
Keywords
- A. Hydrides, A. Microporous materials, C. Infrared spectroscopy, C. X-ray diffraction
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Mechanics of Materials
- Engineering(all)
- Mechanical Engineering
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In: Materials research bulletin, Vol. 46, No. 11, 11.2011, p. 2173-2178.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Thermal behaviour of NaBH4-sodalites with alumosilicate framework
T2 - Influence of cage water content and the surrounding conditions
AU - Hoefs, T. K.
AU - Buhl, J. C.
PY - 2011/11
Y1 - 2011/11
N2 - Sodalites Na8[AlSiO4]6(BH 4)1.8(H3O2)0.2 and Na8[AlSiO4]6(BH4)(H 3O2)0.5(CO3)0.25(H 2O) were examined to characterize the influence of the mixed cage fillings and the surroundings on the thermal behaviour of enclathrated BH 4- and the stability of the alumosilicate framework. The samples were investigated in a NaCl matrix during temperature dependent IR-measurements (TIR) and by thermal analysis in inert atmosphere (helium) and in synthetic air. The thermal products were further characterized by XRD and SEM/EDS. It could be shown that the extent of the BH4- decomposition strongly depends on the cage-fillings of the individual sodalite phase and on the environmental experimental conditions. At low to medium temperatures hydrolysis of BH4- by water molecules from decomposition of H3O2- and H 2O/CO32- templates leads to B(OH) 4-/BH3OH- and via subsequent dehydration to BO(OH)2- and finally BO2 -. At elevated temperatures direct oxidation of BH4 - to BO2- occurs inside the sodalite cages. Further heating results in sodalite framework destruction and finally formation of nepheline with some boron in its structure besides some unknown polymeric borates outside the alumosilicate phase. Framework stability of the sodalites was found to decrease in the direction → heating in NaCl → heating in He-atmosphere → heating in air.
AB - Sodalites Na8[AlSiO4]6(BH 4)1.8(H3O2)0.2 and Na8[AlSiO4]6(BH4)(H 3O2)0.5(CO3)0.25(H 2O) were examined to characterize the influence of the mixed cage fillings and the surroundings on the thermal behaviour of enclathrated BH 4- and the stability of the alumosilicate framework. The samples were investigated in a NaCl matrix during temperature dependent IR-measurements (TIR) and by thermal analysis in inert atmosphere (helium) and in synthetic air. The thermal products were further characterized by XRD and SEM/EDS. It could be shown that the extent of the BH4- decomposition strongly depends on the cage-fillings of the individual sodalite phase and on the environmental experimental conditions. At low to medium temperatures hydrolysis of BH4- by water molecules from decomposition of H3O2- and H 2O/CO32- templates leads to B(OH) 4-/BH3OH- and via subsequent dehydration to BO(OH)2- and finally BO2 -. At elevated temperatures direct oxidation of BH4 - to BO2- occurs inside the sodalite cages. Further heating results in sodalite framework destruction and finally formation of nepheline with some boron in its structure besides some unknown polymeric borates outside the alumosilicate phase. Framework stability of the sodalites was found to decrease in the direction → heating in NaCl → heating in He-atmosphere → heating in air.
KW - A. Hydrides
KW - A. Microporous materials
KW - C. Infrared spectroscopy
KW - C. X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=80052844882&partnerID=8YFLogxK
U2 - 10.1016/j.materresbull.2010.12.029
DO - 10.1016/j.materresbull.2010.12.029
M3 - Article
AN - SCOPUS:80052844882
VL - 46
SP - 2173
EP - 2178
JO - Materials research bulletin
JF - Materials research bulletin
SN - 0025-5408
IS - 11
ER -