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The carbonatation of La2O3oxide and the decarbonatation of lanthanum carbonate phase La2O2CO3are investigated using thermal and thermogravimetry analyses under CO2gas flow. The initial phase La2O3is first elaborated from pyrolysis of a LaOHCO3precursor. Then, thermal and thermogravimetry analyses are carried out under CO2flow, as temperature increases then decreases. The carbonatation kinetics of La2O3is determined at three fixed temperatures. Electrical impedance spectroscopy is performed to determine the electrical responses associated with ionic mobilities and phase changes, in the temperature range 25 to900∘C. The electrical conduction during heating underCO2gas flow should be linked to two regimes of ionic conduction of the carbonate ions. From these electrical measurements, the ionic mobility of carbonate ionsCO3  2−is found to be close to 0.003 ⋅10−4 cm2 s−1 V−1at750∘C for the monoclinic La2O2CO3phase.

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International audienceBismuth tungstate and 5% Lu-doped bismuth tungstate photocatalysts were synthesized by coprecipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra (DRS), and Brunauer-Emmett-Teller (BET) surface area. The effect of lutetium doping on electronic structure was investigated using density functional theory calculations (DFT). The change of morphological and optical band gap was conditioned by lutetium doping. Under visible light irradiation, the as-prepared sheet-like Lu-Bi2WO6 sample exhibits the highest visible-light-responsive photocatalytic performance than pure Bi2WO6 for the degradation of Methylene Blue (MB). The photocatalytic mechanism was explained on the basis of electrochemical impedance spectroscopy (EIS), photoluminescence (PL) spectra, active trapping measurements and optoelectronic properties