| 11. |
- Chaim, Rachman, et al.
(författare)
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Transparent yttrium aluminum garnet (YAG) ceramics by spark plasma sintering
- 2007
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 27:11, s. 3331-3337
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Tidskriftsartikel (refereegranskat)abstract
- Commercial nanocrystalline yttrium aluminum garnet (nc-YAG) powders were used for fabrication of dense and transparent YAG by spark plasma sintering (SPS). Spherical 34 nm size particles were densified by SPS between 1200 and 1500 degrees C using 50 and 100 MPa pressures for 3, 6, and 9 min durations. Fully dense and transparent polycrystalline cubic YAG with micrometer grain size were fabricated at very moderate SPS conditions, i.e. 1375 degrees C, 100 MPa for 3 min. Increase in the SPS duration and pressure significantly increased the density especially at the lower temperature range. The observed microstructure is in agreement with densification by nano-grain rotation and sliding at lower densities, followed by curvature driven grain boundary migration and normal grain growth at higher densities. Residual nanosize pores at the grain boundary junctions are an inherent microstructure feature due to the SPS process.
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| 12. |
- Dominguez-Rodriguez, Arturo, et al.
(författare)
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Making ceramics ductile at low homologous temperatures
- 2007
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 56:2, s. 89-91
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline ceramics are brittle at room temperature but may deform by dislocation slip processes at higher temperatures, where T >= 0.5 T-M (T-M, the melting temperature), leading to strain hardening, i.e. the total strain to rupture is limited. We show that mutual sliding of nanometer grains and atomic transport along their boundaries enables low-temperature metal-like plasticity in nanocrystalline ceramics. Compression of fully dense MgO nanoceramics at temperatures as low as 700 degrees C (0.31 T-M) exhibited stress-strain curves with no strain hardening.
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| 13. |
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| 14. |
- He, Z., et al.
(författare)
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Processing and characterization of nano-structured ZrO2/ CoSb3 thermoelectric composites
- 2006
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Konferensbidrag (refereegranskat)abstract
- The addition of ceramic inclusion to a thermoelectric matrix could reduce the thermal conductivity of the composite, which is attributed to phonon scattering on the generated interfaces. The electrical conductivity of the composite, however, could also be reduced due to additional charge carrier scattering. The performance of the thermoelectric composite, therefore, depends on the resulting ratio of electrical conductivity to thermal conductivity, which results from the entire scattering effects on phonons and charge carriers. In the present work, nano-sized ZrO2 powders of different contents, which were expected to minimize their scattering impact on charge carriers, were dispersed into submicron-sized CoSb3 powders via ball milling. The as-milled powders were consolidated into dense compacts by hot pressing. The phase, the microstructure, and the thermoelectric properties of the prepared compacts were characterized. The correlation of phase purity, microstructure, and thermoelectric properties (electrical conductivity, thermal conductivity, and ratio of electrical conductivity to thermal conductivity), with the ceramic content and sintering temperature is presented. The results show how the performance of the investigated thermoelectric composites can be affected by the dispersion of nano-sized ceramic inclusions. It is noted that the selection of appropriate inclusion content is crucial to maintaining or improving the ratio of electrical conductivity to thermal conductivity.
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| 15. |
- Hu, Z, et al.
(författare)
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Outbreaks of hemotrophic mycoplasma infections in China
- 2009
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Ingår i: Emerging infectious diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6059 .- 1080-6040. ; 15:7, s. 1139-1140
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 16. |
- Hudson, John A., et al.
(författare)
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Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal
- 2009
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Ingår i: Environmental Geology. - : Springer Science and Business Media LLC. - 0943-0105 .- 1432-0495. ; 57:6, s. 1275-1297
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes current knowledge about the nature of and potential for thermo-hydro-mechanical-chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish A"spo Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall-block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.
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| 17. |
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| 18. |
- Kamba, S., et al.
(författare)
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Magnetodielectric effect and optic soft mode behaviour in quantum paraelectric EuTiO3 ceramics
- 2007
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 80:2, s. 27002-
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Tidskriftsartikel (refereegranskat)abstract
- Infrared reflectivity and time-domain terahertz transmission spectra of EuTiO3 ceramics revealed a polar optic phonon at 6-300K whose softening is fully responsible for the recently observed quantum paraelectric behaviour. Even if our EuTiO3 ceramics show lower permittivity than the single crystal due to a reduced density and/ or small amount of secondary pyrochlore Eu2Ti2O7 phase, we confirmed a magnetic field dependence of the permittivity, also slightly smaller than in single crystal. An attempt to reveal the soft phonon dependence at 1.8K on the magnetic field up to 13T remained below the accuracy of our infrared reflectivity experiment.
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| 19. |
- Li, C. Y., et al.
(författare)
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A wide pH range optical sensing system based on a sol-gel encapsulated amino-functionalised corrole
- 2006
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Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 131:3, s. 388-393
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of a new compound, 10-(4-aminophenyl)-5,15-dimesitylcorrole, and its application for the preparation of optical chemical pH sensors is described. The dye materials were immobilized in a sol - gel glass matrix and characterised upon exposure to aqueous buffer solutions. The response of the sensor is based on the fluorescence intensity changing of corrole owing to multiple steps of protonation and deprotonation. Due to its containing several proton sensitive centers, the 10-(4-aminophenyl)- 5,15-dimesitylcorrole based optode shows a wider response range toward pH than that of tetraphenylporphyrin (TPPH2) and 5,10,15-tris( pentafluorophenyl) corrole (H-3(tpfc)). It shows a linear pH response in the range of 2.17 - 10.30. The effect of the composition of the sensor membrane has been studied and the experimental conditions were optimized. The optode showed good reproducibility and reversibility, and common co-existing inorganic ions did not show obvious interference to its pH measurement.
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| 20. |
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