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See detailElectronic and structural transitions in dense liquid sodium
Raty, Jean-Yves ULg; Schwegler, E.; Bonev, S. A.

in Nature (2007), 449(7161), 448-451451

At ambient conditions, the light alkali metals are free-electron-like crystals with a highly symmetric structure. However, they were found recently to exhibit unexpected complexity under pressure 1-6. It ... [more ▼]

At ambient conditions, the light alkali metals are free-electron-like crystals with a highly symmetric structure. However, they were found recently to exhibit unexpected complexity under pressure 1-6. It was predicted from theory 1.2 - and later confirmed by experiment 3-5 - that lithium and sodium undergo a sequence of symmetry-breaking transitions, driven by a Peierls mechanism, at high pressures. Measurements of the sodium melting curve 6 have subsequently revealed an unprecedented (and still unexplained) pressure-induced drop in melting temperature from 1,000 K at 30 GPa down to room temperature at 120 GPa. Here we report results from ab initio calculations that explain the unusual melting behaviour in dense sodium. We show that molten sodium undergoes a series of pressure-induced structural and electronic transitions, analogous to those observed in solid sodium but commencing at much lower pressure in the presence of liquid disorder. As pressure is increased, liquid sodium initially evolves by assuming a more compact local structure. However, a transition to a lower-coordinated liquid takes place at a pressure of around 65 GPa, accompanied by a threefold drop in electrical conductivity. This transition is driven by the opening of a pseudogap, at the Fermi level, in the electronic density of states - an effect that has not hitherto been observed in a liquid metal. The lower-coordinated liquid emerges at high temperatures and above the stability region of a close-packed free-electron-like metal. We predict that similar exotic behaviour is possible in other materials as well. [less ▲]

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See detailElectronic and thermoelectric properties of Fe2VAl: The role of defects and disorder
Bilc, Daniel ULg; Ghosez, Philippe ULg

in Physical Review. B, Condensed Matter and Materials Physics (2011), 83

Using first-principles calculations, we show that Fe2VAl is an indirect band-gap semiconductor. Our calculations reveal that its semimetallic character (which is sometimes assigned) is not an ntrinsic ... [more ▼]

Using first-principles calculations, we show that Fe2VAl is an indirect band-gap semiconductor. Our calculations reveal that its semimetallic character (which is sometimes assigned) is not an ntrinsic property but originates from magnetic antisite defects and site disorder, which introduce localized in-gap and resonant states changing the electronic properties close to the band gap. These states negatively affect the thermopower S and the power factor equal to S2σ, decreasing the good thermoelectric performance of intrinsic Fe2VAl. [less ▲]

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See detailElectronic Autoionization in Carbon monoxide: The effects of the Vibrational Motion.
Leyh, Bernard ULg; Delwiche, Jacques ULg; Hubin-Franskin, Marie-Jeanne ULg et al

in Chemical Physics (1987), 115

New continuous measurements of the vibrationally resolved photoionization cross sections of CO+ X2Sigma+ and A2Pi between 63 and 83 nm are reported. We assign the Rydberg series converging to CO+ A2Pi ... [more ▼]

New continuous measurements of the vibrationally resolved photoionization cross sections of CO+ X2Sigma+ and A2Pi between 63 and 83 nm are reported. We assign the Rydberg series converging to CO+ A2Pi. The effects of the vibrational motion are interpreted on the basis of the Condon approximation. This approximation is shown to allow a qualitative understanding of the decay of the Rydberg series converging to the A2Pi and B2Sigma+ states of CO+. [less ▲]

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See detailThe electronic Construction and Quality Control in Standardized Testing platform project (e-C&QCST)
Gilles, Jean-Luc ULg; Piette, Sylvie-Anne ULg; Detroz, Pascal ULg et al

in Constantinou, C. P.; Demetriou, D.; al (Eds.) 11th Biennal Conference of the European Association for Research on Learning and Instruction - Multiple Perspectives on Effective Learning Enviroments - Abstracts (2005)

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See detailElectronic contribution to the thermal diffusivity: DyBa2Cu3O7-y and Y0.9Ca0.1Ba2Cu3O7-z
Dorbolo, Stéphane ULg; Bougrine, Hassan ULg; Ausloos, Marcel ULg

in International Journal of Modern Physics B : Condensed Matter Physics, Statistical Physics, Applied Physics (1998), 12(29-31), 3087-3090

The electronic contribution to the specific heat and the thermal conductivity of high-T-c superconductors is calculated with a three-dimensional band structure including saddle points and a Lawrence ... [more ▼]

The electronic contribution to the specific heat and the thermal conductivity of high-T-c superconductors is calculated with a three-dimensional band structure including saddle points and a Lawrence-Doniach coupling between the CuO2 planes. The electronic thermal diffusivity is deduced for s- and d-wave symmetry of the order parameter. Data on DyBa2Cu3O7-y and Y0.9Ca0.1Ba2Cu3O7-z and theory are in good agreement on the change of the slope near T-c. [less ▲]

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See detailElectronic Control of Spin Coupling in Keplerate-Type Polyoxomolybdates
Botar, Bogdan; Ellern, Arkady; Hermann, Raphaël ULg et al

in Angewandte Chemie International Edition (2009), 48(48), 9080-9083

We recently identified a synthetic procedure for the isolation of Keplerate structures based on the reaction of multivalent heterometal centers with larger polyoxomolybate(V/VI) units that coexist in a ... [more ▼]

We recently identified a synthetic procedure for the isolation of Keplerate structures based on the reaction of multivalent heterometal centers with larger polyoxomolybate(V/VI) units that coexist in a reaction solution at a certain pH. This approach yielded Keplerate clusters of the type {Mo72Mo8V22},[16] {Mo72V15Fe7Mo8}, and {Mo72V11Fe11Mo8},[14] which were obtained as kinetic products within minutes to a few hours following addition of KCl. Herein, we demonstrate for an analogous reaction system, how novel {Mo72Fe30} Keplerate species with partially reduced {(Mo)Mo5} building blocks (Robin–Day class III) can be identified, based on Raman spectroscopy time profiles of acidified aqueous molybdate reaction solutions. [less ▲]

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See detailElectronic Media and Political Knowledge among 16- to 21-year- old French-speaking Belgians
Fournier, Bernard ULg; Flaba, Elodie ULg

Conference (2009, September 12)

Few studies have looked at the Internet as a source of political knowledge, particularly in Belgium. In April 2009, a questionnaire distributed to 1000 young people between 16 and 21 years of age as well ... [more ▼]

Few studies have looked at the Internet as a source of political knowledge, particularly in Belgium. In April 2009, a questionnaire distributed to 1000 young people between 16 and 21 years of age as well as a citizen’s conference of another 100 young adults addressed various political issues (commitment, citizenship, participation and political interest) and measured, among other things, the impact of the Internet. This paper presents some of our preliminary findings: it confirms that the traditional idea of interest in politics is shared by one third of your sample, that the non-traditional views on politics is certainly higher, but we argue that the political use of the Web is limited to people already strongly interested in politics. [less ▲]

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See detailElectronic nose : a promising tool for landfill odour monitoring
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Delva, Julien ULg

in Lehmann, Ernest C. (Ed.) Landfill research focus (2007)

The paper briefly presents the advantages and drawbacks of the use of electronic noses to monitor continuously the odours generated by a landfill area. It stresses more particularly on the remaining ... [more ▼]

The paper briefly presents the advantages and drawbacks of the use of electronic noses to monitor continuously the odours generated by a landfill area. It stresses more particularly on the remaining obstacles to surmount before using the technique on a routine level. [less ▲]

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See detailThe electronic nose as a warning device of the odour emergence in a compost hall
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Ledent, C.

in Marco, S.; Montoliu, I. (Eds.) Proceedings of the 11th International Symposium on olfaction and electronic nose (ISOEN 2005) (2005, April)

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as ... [more ▼]

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as discriminant analysis, are able to recognize, in real time, the odour of compost with respect to other possible sources in the hall. The paper shows that with unsupervised methods, such as principal component analysis, it is not essential to identify all the possible odour sources during the learning phase. The closeness to the compost group centroid could be used as an indicator of the compost odour level. Alternatively, by a suitable calibration from olfactory measurements, the signals generated by the sensor array can be used to estimate the odour emission rate from the compost hall. Such real time monitoring should allow to assess and to anticipate the annoyance in the surrounding. [less ▲]

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See detailThe electronic nose as a warning device of the odour emergence in a compost hall
Nicolas, Jacques ULg; Romain, Anne-Claude ULg; Ledent, Catherine

in Sensors and actuators. B, Chemical (2006), 116(1-2), 95-99

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as ... [more ▼]

A self-made electronic nose consisting in a sensor array of six commercial tin oxide gas sensors is used to monitor the odour emission from a compost facility. Supervised data processing tools, such as discriminant analysis, are able to recognize, in real time, the odour of compost with respect to other possible sources in the hall. The paper shows that with unsupervised methods, such as principal component analysis, it is not essential to identify all the possible odour sources during the learning phase. The closeness to the compost group centroid could be used as an indicator of the compost odour level. Alternatively, by a suitable calibration from olfactory measurements, the signals generated by the sensor array can be used to estimate the odour emission rate from the compost hall. Such real time monitoring should allow to assess and to anticipate the annoyance in the surrounding. [less ▲]

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See detailElectronic nose for reactor stability monitoring of an agricultural co-digestion biogas plant
Adam, Gilles ULg; Lemaigre, Sébastien; Delfosse, Philippe et al

in Progress in Biogas III - Biogas Production from agricultural biomass and organic residues (2014, September)

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See detailElectronic properties and quantum transport in Graphene-based nanostructures
Dubois, Simon; Zanolli, Zeila ULg; Declerck, Xavier et al

in European Physical Journal B -- Condensed Matter (2009), 72(1), 1-24

Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic ... [more ▼]

Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic, thermal and mechanical properties of graphene and are thus promising candidates for a wide range of nanoscience and nanotechnology applications. In this paper, the electronic and quantum transport properties of these carbon nanomaterials are reviewed. Although these systems share the similar graphene electronic structure, confinement effects are playing a crucial role. Indeed, the lateral confinement of charge carriers could create an energy gap near the charge neutrality point, depending on the width of the ribbon, the nanotube diameter, the stacking of the carbon layers regarding the different crystallographic orientations involved. After reviewing the transport properties of defect-free systems, doping and topological defects (including edge disorder) are also proposed as tools to taylor the quantum conductance in these materials. Their unusual electronic and transport properties promote these carbon nanomaterials as promising candidates for new building blocks in a future carbon-based nanoelectronics, thus opening alternatives to present silicon-based electronics devices. [less ▲]

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See detailElectronic Properties as a Function of Ag/Sb Ratio in Ag1-yPb18Sb1+zTe20 Compounds
Dadda, Jayaram; Mueller, Eckhard; Klobes, Benedikt et al

in Journal of Electronic Materials (2012), 41(8), 2065-2072

In this study efforts have been made to optimize the electronic properties such as the electrical conductivity and Seebeck coefficient of Ag1- (y) Pb18Sb1+ (z) Te-20 (lead-antimony-silver-tellurium, LAST ... [more ▼]

In this study efforts have been made to optimize the electronic properties such as the electrical conductivity and Seebeck coefficient of Ag1- (y) Pb18Sb1+ (z) Te-20 (lead-antimony-silver-tellurium, LAST-18) compounds by systematically varying the Ag and Sb compositions with constant Pb/Te ratio. It was found that increasing the content of Sb relative to Ag raised the charge carrier density (n) and thereby the electrical conductivity and power factor. The results indicate that, for deficient Ag, the excess trivalent Sb atoms occupy divalent Pb sites in the unit cell, increasing the value of n in the system. It was established that the Seebeck coefficient decreases with increasing n indicating a dominant acoustic phonon scattering mechanism in the current alloys. The results demonstrate that the interaction between Ag and Sb atoms plays a major role in determining the electronic properties in the current Ag1-y Pb18Sb1+z Te-20 compounds. [less ▲]

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See detailElectronic properties of simple metals, electronegativity scales and alloy formation
Magain, Pierre ULg; Heinrichs, J.

in Physica B: Condensed Matter (1982), 112

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See detailElectronic properties of the Mg2Si thermoelectric material investigated by linear-response density-functional theory
Boulet; Verstraete, Matthieu ULg; Crocombette et al

in Computational Materials Science (2011), 50(3), 847-851

This paper presents Density-Functional Perturbation Theory (DFPT) calculations on the electronic, vibrational, and electron–phonon (EP) coupling properties of the Mg2Si thermoelectric compound. The DFPT ... [more ▼]

This paper presents Density-Functional Perturbation Theory (DFPT) calculations on the electronic, vibrational, and electron–phonon (EP) coupling properties of the Mg2Si thermoelectric compound. The DFPT yields very satisfactory results for the electronic and vibrational properties when compared to experiment. Regarding the EP interactions, as far as we know, they have never been reported so far. We show that the EP interactions in Mg2Si mainly involve the silicon atom. This result explains the improvement of the thermoelectric properties of Mg2Si using a solid solution Mg2Si1−xAx, where A is a heavier atom than Si. By guiding the choice of the substitution site, the study of the EP coupling properties could be used in the search of new thermoelectric materials based on solid solutions. [less ▲]

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See detailElectronic properties of U2Ni2Sn
Kindo, Koichi; Fukushima, T.; Kumada, T. et al

Poster (1994, August)

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See detailElectronic properties of U2Ni2Sn
Kindo, Koichi; Fukushima, T.; Kumada, T. et al

in Journal of Magnetism & Magnetic Materials (1995), 140-144(2), 1369-1370

We report on the bulk electronic properties of U2Ni2Sn, which crystallizes in the tetragonal U3Si2 structure. Pronounced anomalies in the temperature dependencies of magnetic susceptibility, specific heat ... [more ▼]

We report on the bulk electronic properties of U2Ni2Sn, which crystallizes in the tetragonal U3Si2 structure. Pronounced anomalies in the temperature dependencies of magnetic susceptibility, specific heat and electrical resistivity indicate magnetic ordering below TN = 26 K. An antiferromagnetic ground state is corroborated by the occurrence of three metamagnetic transitions at about 30, 39 and 51 T in the field dependence of the magnetization. The lack of any saturation tendency in the highest field applied (57 T) may suggest further transition(s) to occur in even higher fields. [less ▲]

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See detailElectronic specific heat of superconductors with Van Hove singularities : Effect of a magnetic field and thermal fluctuations
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; houssa, michel

in Physical Review. B : Condensed Matter (1998), 57

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See detailElectronic Speckle Pattern Interferometry at Long Infrared Wavelengths. Scattering Requirements
Vandenrijt, Jean-François ULg; Thizy, Cédric ULg; Alexeenko, Igor et al

in Osten, Wolfgang; Kujawinska, Malgorzata (Eds.) Fringe 2009 (2009, September)

Detailed reference viewed: 54 (5 ULg)