| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Sardh, E, et al.
(författare)
-
Overall Health, Daily Functioning, and Quality of Life in Acute Hepatic Porphyria Patients: ENVISION, a Phase 3 Global, Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial
- 2020
-
Ingår i: DIGESTIVE AND LIVER DISEASE. - : Elsevier BV. - 1590-8658. ; 52, s. E35-E35
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 5. |
- Zelenina, A., et al.
(författare)
-
Silicon nanocrystals in SiNx/SiO2 hetero-superlattices : The loss of size control after thermal annealing
- 2014
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:24, s. 244304-
-
Tidskriftsartikel (refereegranskat)abstract
- Superlattices containing 3 nm thick silicon rich silicon nitride sublayers and 3 nm and 10 nm thick SiO2 barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3 nm SiO2 barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5-12.5 nm, which were randomly distributed within the structure. Although in the sample with 10 nm SiO2 barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10 nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiNx/SiO2 superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885 nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO2 barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms.
|
|
| 6. |
- Zelenina, A., et al.
(författare)
-
Structural and optical properties of size controlled Si nanocrystals in Si3N4 matrix : The nature of photoluminescence peak shift
- 2013
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 114:18, s. 184311-
-
Tidskriftsartikel (refereegranskat)abstract
- Superlattices of Si3N4 and Si-rich silicon nitride thin layers with varying thickness were prepared by plasma enhanced chemical vapor deposition. After high temperature annealing, Si nanocrystals were formed in the former Si-rich nitride layers. The control of the Si quantum dots size via the SiNx layer thickness was confirmed by transmission electron microscopy. The size of the nanocrystals was well in agreement with the former thickness of the respective Si-rich silicon nitride layers. In addition X-ray diffraction evidenced that the Si quantum dots are crystalline whereas the Si3N4 matrix remains amorphous even after annealing at 1200 degrees C. Despite the proven Si nanocrystals formation with controlled sizes, the photoluminescence was 2 orders of magnitude weaker than for Si nanocrystals in SiO2 matrix. Also, a systematic peak shift was not found. The SiNx/Si3N4 superlattices showed photoluminescence peak positions in the range of 540-660nm (2.3-1.9 eV), thus quite similar to the bulk Si3N4 film having peak position at 577nm (2.15 eV). These rather weak shifts and scattering around the position observed for stoichiometric Si3N4 are not in agreement with quantum confinement theory. Therefore theoretical calculations coupled with the experimental results of different barrier thicknesses were performed. As a result the commonly observed photoluminescence red shift, which was previously often attributed to quantum-confinement effect for silicon nanocrystals, was well described by the interference effect of Si3N4 surrounding matrix luminescence.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Estrader, Marta, et al.
(författare)
-
Origin of the large dispersion of magnetic properties in nanostructured oxides : FexO/Fe3O4 nanoparticles as a case study
- 2015
-
Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 7:7, s. 3002-3015
-
Tidskriftsartikel (refereegranskat)abstract
- The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.
|
|
| 10. |
|
|
