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ID 20043
file
creator
Hino, Satoshi
Leng, Haiyan
Fujii, Hironobu
subject
Hydrogen storage materials
Gas-solid reactions
High-energy ball milling
Mechanochemical synthesis
Thermal analysis
NDC
Physics
abstract
After synthesizing calcium amide (Ca(NH2)2) through the reaction of calcium hydride (CaH2) with ammonia (NH3), the thermal decomposition properties have been examined. The results indicated that Ca(NH2)2 decomposed to calcium imide (CaNH) and NH3 gas with increasing temperature, where the desorption of NH3 started from about 60 °C and peaked around 300 °C in the thermal desorption mass spectra (TDMS). From the X-ray diffraction profiles, the product after heat treatment up to 350 °C was CaNH, but an unknown phase appeared in further heating up to 500 °C. Hydrogen (H2) desorption properties of a mixture of Ca(NH2)2 and CaH2 with 1:3 molar ratio were also examined. The H2 gas of 3.5 wt.% in total was desorbed with two-peak structure in TDMS. The first peak corresponds to the reaction: Ca(NH2)2 + CaH2 → 2CaNH + 2H2, and the second one originates in the reaction: CaNH + CaH2 → Ca2NH + H2. Simultaneously performed differential thermal analysis indicated that the former and the latter reactions were respectively exothermic and endothermic, so that the H2 desorption corresponding to the first peak in TDMS disappeared after long time milling at room temperature.
journal title
Journal of Alloys and Compounds
volume
Volume 398
issue
Issue 1-2
start page
62
end page
66
date of issued
2005-08-02
publisher
Elsevier B.V.
issn
0925-8388
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2005 Elsevier B.V.
relation url
department
Graduate School of Advanced Sciences of Matter
Natural Science Center for Basic Research and Development
Institute for Advanced Materials Research