An interdisciplinary approach to the study of kiln firing: a case study from the Campus Galli open-air museum (southern Germany)

Pottery kilns are a common feature in the archaeological record of different periods. However, these pyrotechnological installations are still seldom the target of interdisciplinary investigations. To fill this gap in our knowledge, an updraft kiln firing experiment was run at the Campus Galli open-air museum (southern Germany) by a team consisting of experimental archaeologists, material scientists, geoarchaeologists, and palaeobotanists. The entire process from the preparation of the raw materials to the firing and opening of the kiln was carefully recorded with a particular focus on the study of the raw materials used for pottery making, as well as on fuel usage. The temperatures were monitored by thermocouples placed at different positions in the combustion and firing chambers. In addition, thermocouples were installed within the kiln wall to measure the temperature distribution inside the structure itself. Unfired raw materials as well as controlled and experimentally thermally altered ceramic samples were then characterised with an integrated analysis including ceramic petrography, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and portable X-ray fluorescence (pXRF). Our work provides data about mineralogical and microstructural developments in both pottery kiln structures and the ceramics produced in this type of installations. This is helpful to discuss the limits and potential of various scientific analyses commonly used in ancient ceramic pyrotechnological studies. Overall, our work contributes to a better understanding of updraft kiln technology and offers guidelines on how to address the study of this type of pyrotechnological installations using interdisciplinary research strategies

Optical properties. of PZN-PT nanoparticles thin layers for PV applications

International audienceIn this work, undoped and Mn doped Pb(Zn1/3Nb2/3)O3-4.5PbTiO3 nanoparticles were dispersed in biopolymer and in mixed biopolymer + pentacene as active layer and deposited by spin coating on ITO glasses. Morphological, optical and electrical properties of these layers were investigated. SEM images show the superposition of different deposited layers ITO/TiO2/PZN-PT-np-biopolymer on glass substrate with thicknesses of 1.600 µm, 1.505 µm and 1.765 µm respectively. The absorbance value in UV visible for pentacene layer increases from 75 % to 99 % while the transmittance for ITO glasses diminishes from more than 80 % to 2 %. Optical gaps of ITO, TiO2, PZN-PT nanoparticles are respectively 3.75 eV, 3.2 eV and 3.15 eV. Pentacene deposition reduced the gap to 1.65 eV for undoped sample and 1.60 eV for the doped ones. Intermediate gaps (2.3 eV and 2.6 eV for undoped sample and 2.15 eV and 2.7 eV for doped sample) were observed. Photoluminescence performed between 450 nm and 750 nm confirms « these intermediate gaps »

Micro OLED rapide sur électrodes coplanaires pour un fonctionnement en régime d'excitation impulsionnelle nanoseconde

Dans ce travail, nous nous intéressons à la conception, à la réalisation de micro-OLEDs ultra rapides et à leur caractérisation en régime d’excitation électrique impulsionnelle nanoseconde. Les réponses ultra-rapides de ces μ-OLED sont obtenues par des électrodes spécifiques empruntées aux techniques micro-ondes. Cette combinaison de l’électronique organique et des techniques micro-ondes permet d’atteindre des valeurs record en termes de durée d'impulsion d’excitation ultra courte (5 ns) et de densité de courant ultra-intense (4,7 kA/cm2). Ces résultats ouvrent des perspectives vers la réalisation de la première diode laser organique

Analysis of Optical and Electrical Responses of μ-OLED With Metallized ITO Coplanar Waveguide Electrodes Submitted to Nanosecond Electrical Pulses

International audienceIn this work, the optical and electrical pulse responses of an optimized high-speed organic light emitting diode (OLED) is investigated as a function of the pulse duration. The original design is based on coplanar waveguide electrodes that are implemented on a transparent and conductive oxide thin film. The optimized electrodes with reduced serial resistances allow to feed the organic hetero-structure with fast electrical pulses of few nanosecond in duration, for the first time. This new design of OLED electrodes using microwave techniques ensures to maximize the pulse energy delivery to the organic heterostructure. This is achieved by designing the electrodes to have 50 Ω characteristic impedance and by implementing small values of capacitance (4.5 pF) and of serial resistance (21 Ω). Experimental results demonstrate µ-OLED electrical and optical responses to electrical excitation pulses as short as 2.5ns in duration, for the first time, and state-of-the-art current densities above 1.7 kA/cm 2. Moreover, and rather unexpectedly, the developed characterization procedure to extract the reported results, opened the potential to access time-resolved electroluminescence lifetime of organic materials in the nanosecond time scale

Optimal design of a microcavity organic laser device under electrical pumping

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Towards Optical and Electrical optimization of an OLED heterostructure in a vertical microcavity

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Optimisation du facteur de qualité d'une OLED en microcavité : vers des diodes lasers organiques

International audienceCette étude a pour objectif l'optimisation du facteur de qualité de micro cavités destinées à permettre la réalisation de diodes lasers organiques. Le confinement vertical assuré par une structure de type VECSEL à miroirs multicouches et le confinement latéral assuré par des matériaux nanostructurés à bande interdite sont étudiés et discutés. Plus particulièrement, les facteurs de qualité de microcavités à base de trois couples de matériaux différents TiO2/SiO2, Ta2O5/SiO2, Mgf2/ZnS, sont comparés et étudiés en fonction du nombre de couches des miroirs. Des facteurs de qualités supérieurs à 10 000 sont obtenus pour des structures optimisées à cavités étendues