Effect of Annealing Temperature on the Li+^{ + } Ionic Conductivity of La0.67−x_{0.67 - x}Li3x_{3x}TiO3_{3 }

Perovskite La0.67-xLi3xTiO3 with x = 0.10, 0.11, 0.12 and 0.13 were firstly annealed at 800 oC then treated by reactive milling, followed by post-annealing at temperatures from 1100 to 1200oC. The crystalline structure of grain and grain-boundary were characterized by XRD and SEM. The impedance measurements showed that nanocrystalline La0.67-xLi3xTiO3 after being annealed at 1150 oC possessed a grain conductivity as high as 1.3×10-3 S.cm-1. The grain-boundary conductivity was enhanced one order in magnitude after annealing at temperature higher 1100oC and consists of 5.8×10-5 S.cm-1. The results have also showed the limitation of the adiabatic thermal treatment for the improvement of the grain-boundary conductivity and suggested the way to overcome the limitation by rapidly cooling the samples from the high temperature to room temperature

Optical Property and Photoelectrical Performance of a Low-bandgap Conducting Polymer Incorporated with Quantum Dots Used for Organic Solar Cells

By using spin-coating technique, a low bandgap conjugated polymer, poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopen-ta[2,1-b;3,4-b′]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT)  and its composite thin films have been prepared. The optical absorption and photoconductive properties with over a wide spectral range, from 350 to 950  nm, were characterized. The obtained results showed that PCPDTBT:10 wt% CdSe  composite is the most suitable for efficient light-harvesting in polymer-based photovoltaic cells. The photoelectrical conversion efficiency (PCE) of the device with  a multilayer structure of ITO/PEDOT/ PCPDTBT:CdSe /LiF/Al  reached a value as large as 1.34% with an open-circuit voltage (Voc) = 0.57 V, a short-circuit current density (Jsc) = 4.29 mA/cm2, and a fill factor (FF) = 0.27. This suggests a useful application in further fabrication of quantum dots/polymers based solar cells

Spectroscopic and Photoluminescent Properties of Nanostructured Polyfluorenes/TiO2 Composite Films used for OLEDs

In this work we present spectroscopic and photoluminescent properties of nanostructured polymeric composite films of nanocrystalline TiO2 and polyfuorenes (PF+nc-TiO2). The films were deposited onto glass and KBr substrates by spin-coating PF-in-toluene solution with embedding of 5-nm thick nc-TiO2 particles. The nc-TiO2 wt concentration embedded in PF was chosen as 1%, 2% and 4%. The FTIR, FTR, UV-VIS-NIR and photoluminescence characterization were carried-out to study the influence of oxide nanoparticles on the absorption spectra, molecular structures and emissive luminescence of the composites. It was shown that the presence of TiO2 nanoparticles results in improvement of charge separation of carriers generated by light excitation. Under a short wavelength excitation, in some samples a PL enhancement was observed. Under normal or long wavelength excitation, PF fluorescence quenching occurred for all the composites. Aging process of the composites was also investigated

Enhancement of current-voltage characteristics of multilayer organic light emitting diodes by using nanostructured composite films

With the aim of improving the photonic efficiency of an organic light emitting diode (OLED) and its display duration, both the hole transport layer (HTL) and the emitting layer (EL) were prepared as nanostructured thin films. For the HTL, nanocomposite films were prepared by spin-coating a homogeneous solution of low molecular weight poly(4-styrenesulfonate) (PEDOT-PSS) and surfactant-capped TiO2 nanocrystals onto low resistivity indium tin oxide (ITO) substrates; for the EL, nancrystalline titatium oxide (nc-TiO2)-embedded Poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV+nc-TiO2) conjugate polymers were spin-coated onto the HTL. Also, for a shallow contact of Al/LiF/MEH-PPV instead of Al/MEH-PPV a super LiF thin film was deposited onto the EL by vacuum evaporation. The resulting multilayer OLED had the following structure of Al/LiF/MEH-PPV+nc-TiO2/PEDOT-PSS+nc-TiO2/ITO. Characterization of the nanocomposite films showed that both the current-voltage (I-V) characteristics and the photoluminescent properties of the nanocomposite materials were significantly enhanced in comparison with the standard polymers. OLEDs made from these layers would exhibit a large photonic efficiency

Organic - Inorganic Hybrid Luminescent Composite for Solid-state Lighting

White light emitting diodes (WLEDs) made by coating organic and inorganic hybrid composites on blue LED chips. Y3Al5O12:Ce (YAG:Ce) nano inorganic powder prepared by low-temperature Sol-Gel method exhibited broad green emission with the peak at 521 nm. Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) polymer has high luminescence efficiency and red emission peak at 590 nm. The white light was obtained by mixing blue light from emission of the blue LED chip - Indium Gallium Nitride (InGaN) and green-red light from the fluorescence of nano- YAG:Ce and MEH-PPV polymer hybrid composite. The hybrid nanocomposite-based WLEDs exhibited broad band emission spectra from blue light to red wavelengths and provided the white light with a CIE-1931 coordinate of x = 0.2986, y = 0.2620 and a colour rendering index Ra = 84.36. The results suggest a potential application of nanocomposite based WLEDs in efficient solid-state lighting

Effect of Silver Nanowire Dimension to Ammonia Adsorption of Graphene-silver Nanowires Hybrid

In this report, we study the effect of silver nanowires (AgNws) dimension to electrical properties of rGO/AgNws hybrid. The alteration of these electrical properties leads the difference of ammonia sensibility of the rGO/AgNws hybrid based sensing devices. When the rGO is accompanied by AgNws of different sizes from \sim 500$~\text{nm to } 10\;\mum, the ammonia sensitivity of these hybrids change from 60% to 340% alteration compared with the bare rGO material

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Relationship between the variability of urban pollution and socio-cultural context of the collection basin

La variabilité de la pollution urbaine est liée à l'activité humaine qui est elle-même très variable (journalière, hebdomadaire, annuelle, pluri-annuelle). Afin de développer un modèle qui permet de prédire ces différentes variabilités, nous avons analysé des études démographiques, de l'utilisation de l'espace à partir de données cadastrales et des photographies aériennes et réalisés, des campagnes de prélèvements sur 24h. L'exemple de la Communauté Urbaine du Grand Nancy sur l'utilisation de ces outils est illustré dans ce travail. Les résultats de campagnes de prélèvements sur trois type de sous-bassins (village semi-rural, zone résidentielle, zone résidentielle avec un grand hôpital) en fonction de l?activité humaine (jour versus nuit, repas, lavage) sont discutés. Une meilleure anticipation de la variabilité de la pollution arrivant dans les installations de traitement des eaux résiduaires permettrait d'améliorer leur gestion et donc de leur performance. Les campagnes ont également permis une meilleure compréhension de la variabilité de certains micropolluants tels que les métaux lourds. La pollution est moins variable dans une grande ville que dans une localité rurale, elle est liée aux apports des activités professionnelles sur les différents sites. La variabilité dépend de la nature du réseau de collecte, de style de vie, de la démographie du bassin de collecte (en termes de répartition spatiale et de classe d'âge, etc.), des zones étudiées. Les macro-polluants (C, N-NH4, P) et les micro-polluants métalliques (Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Al) ont été caractérisés. Deux pics de pollution ont été observés : le premier pendant le matin vers 10h00 et le second pic en début de soirée vers 20h00. Pour les zones résidentielles le premier pic correspond à l'activité humaine du matin avant de quitter la maison pour travailler, le deuxième pic correspond aux activités à l'heure du retour à la maison après une journée de travail. On n'a pas trouvé un schéma propre aux zones mixtes (résidentielles avec des activités commerciales, industrielles et hospitalières). Les variations du débit et de la composition des eaux usées reproduisent très bien le cycle humain. Dans ce travail, on a tenu en compte les modifications démographiques, l'occupation du sol et le déplacement domicile-travail sur les sites étudiésThe variation of urban pollution related to human activity depends on several spatial and temporal scales: daily, weekly, annual, multi-year. To develop a model predicting this variations, different tools are used including demographic characteristics (age, sex, income), on the basis of cadastral data and aerial photographs and sampling campaigns on 24h. The use of these tools is illustrated with the example of the Urban area of Nancy. The results of sampling campaigns in three different catchments (semi-rural village, residential area, and residential area with large hospital) are discussed, considering its relation with the human activities (day versus night, meals, laundry). Better anticipating the variability of pollution which arrived to the wastewater treatment plant would improve their management and therefore their performances. These measurements also allowed a better understanding of the variability of some micropollutants such as heavy metals. The daily variation pattern in the big city is less marked than rural communities. This variability is probably related to the contributions of professional activities on different sites. It depends on the modification of the collection network, lifestyle, demographics on the water catchment, in terms of spatial distribution and age class in the studied area. The macropollution (C, N-NH4, P) and metal micropollution (Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Al) were considered. Pollution peaks were observed: For residential areas, the first peak corresponds to human activity in the morning (around 10:00) before leaving home to work, the second peak corresponds to the activities at the time of returning home (around 20:00) after a day's work. We did not find a proper scheme for mixed zones (residential with commercial, industrial and hospital activities). Variations in flow and composition of the wastewater reproduce very well the human cycle, taking into account modifications in population, information on land use and daily journeys between home and work in the studied site

Relations entre la variabilité de la pollution urbaine et le contexte socio-culturel du bassin de collecte

Accès restreint aux membres de l'Université de Lorraine jusqu'au 2014-12-06The variation of urban pollution related to human activity depends on several spatial and temporal scales: daily, weekly, annual, multi-year. To develop a model predicting this variations, different tools are used including demographic characteristics (age, sex, income), on the basis of cadastral data and aerial photographs and sampling campaigns on 24h. The use of these tools is illustrated with the example of the Urban area of Nancy. The results of sampling campaigns in three different catchments (semi-rural village, residential area, and residential area with large hospital) are discussed, considering its relation with the human activities (day versus night, meals, laundry). Better anticipating the variability of pollution which arrived to the wastewater treatment plant would improve their management and therefore their performances. These measurements also allowed a better understanding of the variability of some micropollutants such as heavy metals. The daily variation pattern in the big city is less marked than rural communities. This variability is probably related to the contributions of professional activities on different sites. It depends on the modification of the collection network, lifestyle, demographics on the water catchment, in terms of spatial distribution and age class in the studied area. The macropollution (C, N-NH4, P) and metal micropollution (Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Al) were considered. Pollution peaks were observed: For residential areas, the first peak corresponds to human activity in the morning (around 10:00) before leaving home to work, the second peak corresponds to the activities at the time of returning home (around 20:00) after a day's work. We did not find a proper scheme for mixed zones (residential with commercial, industrial and hospital activities). Variations in flow and composition of the wastewater reproduce very well the human cycle, taking into account modifications in population, information on land use and daily journeys between home and work in the studied sitesLa variabilité de la pollution urbaine est liée à l'activité humaine qui est elle-même très variable (journalière, hebdomadaire, annuelle, pluri-annuelle). Afin de développer un modèle qui permet de prédire ces différentes variabilités, nous avons analysé des études démographiques, de l'utilisation de l'espace à partir de données cadastrales et des photographies aériennes et réalisés, des campagnes de prélèvements sur 24h. L'exemple de la Communauté Urbaine du Grand Nancy sur l'utilisation de ces outils est illustré dans ce travail. Les résultats de campagnes de prélèvements sur trois type de sous-bassins (village semi-rural, zone résidentielle, zone résidentielle avec un grand hôpital) en fonction de l?activité humaine (jour versus nuit, repas, lavage) sont discutés. Une meilleure anticipation de la variabilité de la pollution arrivant dans les installations de traitement des eaux résiduaires permettrait d'améliorer leur gestion et donc de leur performance. Les campagnes ont également permis une meilleure compréhension de la variabilité de certains micropolluants tels que les métaux lourds. La pollution est moins variable dans une grande ville que dans une localité rurale, elle est liée aux apports des activités professionnelles sur les différents sites. La variabilité dépend de la nature du réseau de collecte, de style de vie, de la démographie du bassin de collecte (en termes de répartition spatiale et de classe d'âge, etc.), des zones étudiées. Les macro-polluants (C, N-NH4, P) et les micro-polluants métalliques (Na, K, Mg, Ca, Cu, Zn, Mn, Fe, Al) ont été caractérisés. Deux pics de pollution ont été observés : le premier pendant le matin vers 10h00 et le second pic en début de soirée vers 20h00. Pour les zones résidentielles le premier pic correspond à l'activité humaine du matin avant de quitter la maison pour travailler, le deuxième pic correspond aux activités à l'heure du retour à la maison après une journée de travail. On n'a pas trouvé un schéma propre aux zones mixtes (résidentielles avec des activités commerciales, industrielles et hospitalières). Les variations du débit et de la composition des eaux usées reproduisent très bien le cycle humain. Dans ce travail, on a tenu en compte les modifications démographiques, l'occupation du sol et le déplacement domicile-travail sur les sites étudié

CHARACTERISTICS OF LITHIUM LANTHANUM TITANATE THIN FILMS MADE BY ELECTRON BEAM EVAPORATION FROM NANOSTRUCTURED La0.67-xLi 3xTiO3 TARGET

Bulk nanostructured perovskites of La0.67-xLi3xTiO3 (LLTO) were prepared by using thermally ball-grinding from compounds of La2O3, Li2CO3 and TiO2. From XRD analysis, it was found that LTTO materials were crystallized with nano-size grains of an average size of 30 nm. The bulk ionic conductivity was found strongly dependent on the Li+ composition, the samples with x = 0.11 (corresponding to a La0.56Li0.33TiO3 compound) have the best ionic conductivity, which is ca. 3.2 x 10-3 S/cm at room temperature. The LLTO amorphous films were made by electron beam deposition. At room temperature the smooth films have ionic conductivity of 3.5 x 10-5  S/cm and transmittance of 80%. The optical bandgap of the films was found to be of 2.3 eV. The results have shown that the perovskite La0.56Li0.33TiO3  thin films can be used for a transparent solid electrolyte in ionic battery and in all-solid-state electrochromic devices, in particular