| 1. |
- Di Luccio, Tiziana, et al.
(författare)
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Synthesis of CdS nanocrystals in polymeric films studied by in-situ GID and GISAXS
- 2015
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Ingår i: Insights for Energy Materials Using In-Situ Charaterization. - : Springer Science and Business Media LLC. - 0272-9172. - 9781510826625 ; 1810, s. 9-14
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Konferensbidrag (refereegranskat)abstract
- In this work, we describe the synthesis of CdS nanocrystals in thin polymeric films by in-situ Grazing Incidence Diffraction (GID) and Grazing Incidence Small Angle Scattering (GISAXS). The 2D GISAXS patterns indicate how the precursor structure is altered as the temperature is varied from 25°C to 300°C. At 150°C, the CdS nanocrystals start to arrange themselves in a hexagonal lattice with a lattice parameter of 27 A. The diffraction intensity from the hexagonal lattice reaches a maximum at 170"C and decreases steadily upon further heating above 220°C indicating loss of symmetry. Correspondingly, the GID scans at 170°C show strong crystalline peaks from cubic CdS nanocrystals that are about 2 nm size. The results indicate that a temperature of 170°C is sufficient to synthesize CdS nanocrystals without degradation of the polymer matrix (Topas) in thin films (about 30nm).
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| 2. |
- Khachatourian, Malek Adrine, et al.
(författare)
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Green synthesis of Y2O3:Eu3+ nanocrystals for bioimaging
- 2015
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Ingår i: Materials Research Society Symposium Proceedings. - : Materials Research Society. - 9781510806054 ; , s. 59-64
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Konferensbidrag (refereegranskat)abstract
- Rare earth (e.g., Eu, Er, Yb, Tm) doped Y2O3 nanocrystals are promising fluorescent bioimaging agents which can overcome well known problems of currently used organic dyes like photobleaching, phototoxicity, and light scattering. Furthermore, the alternative quantum dots (QDs) composed of heavy metals (e.g., CdSe) possess inherently low biocompatibility due to the heavy metal content. In the present work, monodisperse spherical Y2O3:Eu3+ nanocrystals were successfully synthesized by microwave assisted urea precipitation method followed by thermochemical treatment. This is a green, fast and reproducible synthesis method, which is surfactant and hazardous precursors free. The as prepared particles were non-aggregated, spherical particles with a narrow size distribution. The calcined particles have a polycrystalline structure preserving the monodispersity and the spherical morphology of the as prepared particles. After calcination of Y(OH)CO3:Eu3+ precursors at 900°C for 2 hours, a highly crystalline cubic Y2O3 structure was obtained. The Y2O3:Eu3+ spherical particles showed a strong red emission peak at 613nm due to the 5D0-7F2 forced electric dipole transition of Eu3+ ions under UV excitation (235 nm) as revealed by the photoluminescence analysis (PL). The effect of reaction time on size and photoluminescence properties of calcined particles and also the effect of reaction temperature and pressure on the size and the yield of the precipitation process have been studied. The intense red fluorescent emission, excellent stability and potential low toxicity make these QDs promising for applications in bio-related areas such as fluorescence cell imaging or fluorescence bio labels.
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| 3. |
- Kirstein, Oliver
(författare)
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The European spallation source and future opportunities for materials science
- 2015
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Ingår i: State-of-the-Art Developments in Materials Characterization. - : Springer Science and Business Media LLC. - 9781605117317 ; 1754, s. 111-122
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Konferensbidrag (refereegranskat)abstract
- The European Spallation Source is Europe's next generation high-power neutron source utilising a linear accelerator and a rotating tungsten target to produce neutrons that will be used for fundamental research and industrial applications. The facility is co-hosted by the states of Denmark and Sweden, and while the main site will be placed in Lund, Sweden, the Data Management and Software Centre will be located in Copenhagen, Denmark. The facility will cover a broad range of scientific applications in the fields of physics, chemistry, biology, or life sciences. A focus will also be materials science and engineering, and dedicated instruments will gradually become available to the user community once neutrons will be produced neutrons from 2019 onwards.
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| 4. |
- Nikkam, Nader, et al.
(författare)
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Experimental investigation on thermophysical properties of ethylene glycol based copper micro- and nanofluids for heat transfer applications
- 2015
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Ingår i: Materials Research Society Symposium Proceedings. - : Cambridge University Press. - 9781510826342 ; , s. 69-74
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Konferensbidrag (refereegranskat)abstract
- The present work reports on the fabrication, experimental and theoretical investigatbn of thermal conductivity (TC) and viscosity of ethylene glycol (EG) based nanofluids/microfluids (NFs/MFs) containing copper nanoparticles (Cu NPs) and copper microparticles (Cu MPs). Cu NPs (20-40 nm) and Cu MPs (0.5-1.5 μm) were dispersed in EG with particle concentration from 1 wt% to 3 wt% using powerful ultrasonic agitation, and to study the real impact of dispersed particles the use of surface modifier was avoided. The objectives were to study the effect of concentration and impact of size of Cu particles on thermo-physical properties, including thermal TC and viscosity, of EG based Cu NFs/MFs. The physicochemical properties of NPs/MPs and NFs/MFs were characterized by using various techniques. The experimental results exhibited higher TC of NFs and MFs than the EG base liquid. Moreover, Cu NFs displayed higher TC than MFs showing their potential for use in some heat transfer applications. Maxwell effective medium theory as well as Einstein law of viscosity was used to compare the experimental data with the predicted values for estimating the TC and viscosity of Cu NFs/MFs, respectively.
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| 5. |
- Thorsteinsson, D. O., et al.
(författare)
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Morphology of tantalum nitride thin films grown on fused quartz by reactive high power impulse magnetron sputtering (HiPIMS)
- 2015
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Ingår i: Materials Research Society Symposium Proceedings. - : Materials Research Society. - 9781510826564 ; , s. 21-26
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Konferensbidrag (refereegranskat)abstract
- Thin tantalum nitride films were grown on fused quartz by reactive high power impulse magnetron sputtering (HiPIMS) while varying the fractional N2 flow rate at fixed substrate temperature of 400°C. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. Structural characterization was carried out using X-ray diffraction and reflection methods. The HiPIMS process produces slightly less dense films than does dcMS and the surface roughness is similar for both the HiPIMS and dcMS grown films. The deposition rate for HiPIMS is up to 80 % lower than for dcMS but it can be roughly doubled by lowering the magnetic field strength by 30 %.
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| 6. |
- Yakhshi Tafti, Mohsen, 1983-, et al.
(författare)
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Temperature Dependent Structure Stability Studies on Thermoelectric Yb0.025Fe0.3Co0.7Sb3
- 2015
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Ingår i: Materials Research Society Proceeding. - : Materials Research Society.
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Konferensbidrag (refereegranskat)abstract
- Depending on their application temperature thermoelectric (TE) materials are classified in three main categories; as low (up to 250°C), intermediate (up to 550°C) and high (above 600°C) temperature. Currently, Skutterudites (CoSb3) based materials have shown promising results in the intermediate temperature range (300-500°C). This family of material is highly suitable for automotive, marine transportation and industrial power generation applications to recover the waste heat from the exhaust and generate electricity. Conventional TE modules need p- and n-type semiconductor materials and for the skutterudite family, iron (Fe) has proven to be among the best candidates for the substitution of cobalt sites. Additionally, rare earths are introduced as rattlers in the crystal cages of the skutterudite to decrease the thermal conductivity, thus improving the figure of merit ZT of the TE material. For practical application for device fabrication, stability of these materials is of great importance. Compositional stability is being addressed as the material decomposes above certain temperature. Temperature dependent x-ray diffraction study was performed on Fe substituted, Yb-filled skutterudites, using Beam Line I711 at MAX LAB, to observe the crystal structure as a function of temperature. Diffraction patterns were collected from room temperature up to 500°C by utilizing Huber furnace. The results show success in filling process showing almost 80% reduction of the thermal conductivity from bulk. Additionally the thermal expansion coefficient value was within the average value for skutterudites which proves practical application of this powder for industrial applications.
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| 7. |
- Zhao, Yichen, et al.
(författare)
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Synthesis of nanostructured antimony telluride for thermoelectric applications
- 2015
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Ingår i: Materials Research Society Symposium Proceedings. - : Elsevier. - 9781510806221 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Thermoelectric (TE) materials have been studied during past decades since they can generate electricity directly from waste heat. Antimony chalcogenides (Sb2M3, M = S, Se, Te) are well known as one of the promising candidates among the inorganic TE materials. We report on the synthesis of Sb2Te3 nanoparticle via thermolysis method. A systematic study was done to investigate the effect of reaction time and ratio between the precursors as well as the method of cooling on the morphology and composition of obtained nanoparticles. The ratio between precursors was varied to study the effect on the morphology. Furthermore, the high purity phase Sb2Te3 was obtained by a rapid cooling process.
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