Préparation et propriétés diélectriques du Ba0,90Sr0,10TiO3 dopé au manganèse

National audienceDans le cadre de cette étude, des couches minces de Ba0,90Sr0,10TiO3 dopées au manganèse ont été réalisées par un procédé sol-gel modifié basé sur des précurseurs alkoxydes. La cristallinité et la morphologie des films ont été étudiées montrant que le manganèse ne modifie pas significativement les propriétés structurales du matériau. Les cycles d'hystérésis à 50 Hz ont été mesurés et un cycle saturé présentant les meilleures propriétés a été obtenu pour un dopage à 3 %. La permittivité et les pertes diélectriques (tan ) sont mesurées à 1 MHz en fonction d'un champ continu permettant ainsi d'estimer l'accordabilité et la figure de mérite (F.O.M.) de chaque échantillon. Un dopage au manganèse de 3 % molaire semble finalement offrir le meilleur compromis entre accordabilité et pertes diélectriques

Synthesis and characterization of polymers for nonlinear optical applications

International audienceA difunctional NLO Azo-Dye chromophore has been synthesized and polymerization has been performed with a comonomer bearing a side-chain epoxy group. Deposition of the polymer on glass substrates was performed by spin-coating, resulting in uniform films up to 2 µm thickness. The orientation of the chromophore was performed under a " pin-to-plane " positive corona discharge followed by a heat-treatment in order to obtain reticulation of the films. Molecular orientation has been investigated using UV-Vis. and Raman spectroscopy. Poling of the films results in a decay of absorbency as well as in a blue shift of the spectrum. At the same time, the 1600 cm-1 band disappears from the Raman spectra, indicating orientation of the chromophores. Cross-linking has been studied by FTIR and all-optical poling and showed an improved stability of the electro-optic thin films

Préparation et caractérisation de couches minces ferroélectriques par la méthode Sol-Gel

International audienc

Matériau piézoélectrique flexible : nouveau procédé pour la récupération d’énergie

National audienc

Preparation of antiferroelectric PZT thin films on bare and RuO2 coated steel substrates

International audiencePZT antiferroelectric thin films have been prepared by chemical solution deposition using alkoxide precursor compounds. With the aim to establish the compositional transition from the ferroelectric to the antiferroelectric phase state, the films were prepared with different Zr/Ti-ratio ranging from 92/8 to 100/0. In order to compare the dielectric properties of the films, deposition of the PZT was either on bare steel substrates or on substrates coated with an RuO2 interface layer.In general, the PZT films with the additional RuO2 layer had smaller coercive fields, while the values of spontaneous polarization essentially did not differ. The clearest double hysteresis characteristic was obtained for PZT (95/5); using conventional multi-coating technique, homogeneous films of up to 2.5 um thickness were prepared

Ultra light tunable capacitor based on PZT thin film deposited onto aluminium foil

International audienceLead zirconate titanate (PZT) thin films with a Zr/Ti ratio of 57/43, elaborated by a derived sol-gel process, have been deposited onto bare and RuO2 coated aluminium substrate 16 μm thick. Commercial aluminium foil presents many advantages as ultra light weight (43 g m−2), conformability, conduction, can be easily cut, and is one of the cheapest substrates used for PZT thin films deposition (<0.1$ m-2). XRD measurements have shown a well crystallized PZT in the perovskite structure and ferroelectric behaviour has also been observed. By the use of a RuO2 film 100 nm thick at the PZT/aluminium interface, the coercive field and tunability values have been strongly improved despite an increase of the dielectric losses. The lead excess introduced in the precursor solution has been increased up to 65 % in order to lower the crystallization temperature of the PZT around 560 °C and tunability has been studied as a function of annealing time and temperature

Mise en place et analyse du mode comodal dans une unité d'enseignement de Licence

International audienc

Piezoelectric response of a PZT thin film to magnetic fields from permanent magnet and coil combination

International audienc

Influence of the process parameters on the structural and electric properties of ferroelectric and antiferroelectric PZT thin films realized on stainless steel by a Sol-gel derived method

International audiencePbxZryTi1−yO3 thin films were prepared by a modified Sol–gel method using alkoxides precursor compounds and spin-coating onto RuO2 coated stainless steel substrates. Depending on the zirconate/titanate ratio, both, ferroelectric and antiferroelectric behaviour has been obtained. Oxidation of the metal substrate due to the PZT crystallization process was studied in order to verify the influence of the heat treatment on the substrate morphology. In order to improve the properties of antiferroelectric PbxZr0.95Ti0.05O3, the influence of the lead excess in the composition was investigated. Thefs dependence of the switching field distribution from the annealing time and temperature, as well as the fatigue behaviour of the films, is discussed

REALISATION ET CARACTERISATION DE COUCHES MINCES FERROELECTRIQUES ET ANTIFERROELECTRIQUES DE PZT

NANTES-BU Sciences (441092104) / SudocSudocFranceF