Synthesis of 0.94 Na0.5Bi0.5TiO3 – 0.06 BaTiO3 (NBT-6BT) lead-free piezoelectric powder suitable for aerosol deposition (AD)

International audienceThe present work is devoted to the synthesis of 0.94 (Na0.5Bi0.5)TiO3-0.06 (BaTiO3) powders by solid-state reaction, suitable for Aerosol Deposition method (AD). The powders were synthetized using Na2CO3, Bi2O3, BaCO3 and TiO2. The raw powders were simultaneously milled / mixed by attrition milling in water. Two routes were studied, differing by the order of introduction of the raw materials, for three calcination temperatures. The first route (S1) led to the occurrence of Bi2Ti2O7 pyrochlore secondary phase. Attempts to suppress this phase by annealing were unsuccessful. The second route (S2) gave no secondary phase. The large grain size obtained at 950°C and 1050°C are not suitable for sintering or AD. However, the process carried out at 850°C resulted in powders suitable for both sintering and AD method. The ferroelectric and piezoelectric properties of the ceramic samples obtained using these powders are similar to the best-reported ones. Finally, we successfully used these powders for AD

Elaboration of lead-free Na0.5Bi0.5TiO3–BaTiO3 (NBT-BT) thick films by aerosol deposition method (ADM)

International audienceThick and dense ceramic films of lead-free 0.94 Na 0.5 Bi 0.5 TiO 3 – 0.06 BaTiO 3 (NBT-BT) composition were elaborated by aerosol deposition method (ADM) at room temperature. A powder of suitable grain size was elaborated by solid state reaction. Using this powder, two samples were elaborated by ADM respectively on glass and metallic substrates, in order to check for microstructure and electrical properties. This process allowed obtaining a thick film (3.2 µm) with dense microstructure. Measurement of electrical properties revealed a lossy dielectric behavior indicating interfacial phenomena at the electrode – film interface. The measurement of the ferroelectric hysteresis cycle does not show any characteristics of a ferroelectric behavior, but corresponds well to the one of a lossy non-linear dielectric. The absence of ferroelectricity is probably due to the low grain size of the obtained thick film (130 nm). Further experiments are in progress in order to try to obtain ferroelectric properties

Chemical modification of silicon carbide precursors for 3D printing (VIRTUAL)

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Chemical modification of silicon carbide precursors for Direct Ink Writing

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Modification chimique de précurseurs de carbure de silicium pour impression directe

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Dense and highly textured coatings obtained by aerosol deposition method from Ti3SiC2 powder: Comparison to a dense material sintered by Spark Plasma Sintering

International audienceA commercial Ti3SiC2 MAX-phase powder of micron size was impacted onto glass substrates by aerosol deposition method (ADM) to get dense and adhesive films without sintering and with thicknesses up to 16μm. The overall grain organization follows a wavelike texture with some significant grain deformation. Individual grains appear elongated and c-oriented. Grain boundaries are made of amorphous phase with small Ti3SiC2 crystallites of a size lower than 10nm embedded. This structure is similar to that observed at the interface with the substrate where grain fragmentation is more pronounced. Inside grains, Ti3SiC2 typical nano-lamellar structure is clearly seen, as well as some crystal deformations quantified around 2.5%. XRD analyses are in accordance to TEM results and the mean crystallite size calculated evolves with the thickness. It is equal to a few nanometers close to the substrate up to an average of 40-50nm for thicker films