| 1. |
- Mosegaard, Lene, et al.
(författare)
-
Intermediate phases observed during decomposition of LiBH4
- 2007
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 446-447, s. 301-305
-
Konferensbidrag (refereegranskat)abstract
- Lithium tetrahydridoboranate is among the materials with the highest hydrogen content and has great potential as a possible H-2-storage material, although, the release and uptake of H-2 is not fully understood. In this work, LiBH4 was studied by in situ synchrotron radiation powder X-ray diffraction (PXD) and solid state CP/MAS NNIR both at variable temperatures. This study revealed two new phases observed during dehydrogenation of LiBH4. Phase I is hexagonal, a = 4.93(2) and c = 13.47(3) angstrom and is observed in the temperature range -200-300 degrees C, and phase II is orthorhombic, a = 8.70(1), b = 5.44(1) and c = 4.44](8) angstrom and is observed in the temperature range similar to 300-400 degrees C applying a constant heating rate of 5 degrees C/min. Apparently, I transforms into II, e.g. at a constant temperature of T= 265 degrees C after 5 h. Furthermore, a third phase, III, is observed in the temperature range RT to 70 degrees C, and is caused by a reaction between LiBH4 and water vapor from the atmosphere. Hydrogen release is associated with the decomposition of III at ca. 65 degrees C. (C) 2007 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Åhlund, John, et al.
(författare)
-
The adsorption of iron phthalocyanine on graphite : A scanning tunnelling microscopy study
- 2007
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 601:17, s. 3661-3667
-
Tidskriftsartikel (refereegranskat)abstract
- Different adsorption phases of iron phthalocyanine (FePc) on highly oriented pyrolitic graphite (HOPG) have been characterized by scanning tunnelling microscopy (STM). Evaporation of FePc onto the graphite (0 0 0 1) surface, kept at room temperature, results in the formation of three-dimensional molecular islands.After annealing to 400 °C different two-dimensional features are identified, depending on the initial coverage. At low doses, domains with well defined boundaries have been observed, within which molecules tend to organise in chains. At higher coverage, islands exhibiting well-ordered densely-packed square or hexagonal molecular arrangement have been resolved. For the adsorption structures corresponding to one monolayer islands our results show that the molecules adsorb with the molecular plane parallel to the surface. The high resolution STM images allow us to resolve the orientation of single molecules and subsequently we suggest that the molecular monolayer is stabilized by van der Waals interactions. The characterization of the observed Moiré contrast and a comparison with other similar systems underlines the importance of the central metal in the molecule–molecule and molecule–substrate interactions, which govern the molecular adsorption geometry.
|
|
