An in-situ real-time study on solid phase formation and its degree of structural disorder could shed light on the mechanisms of solidification from the liquid and allow insight into the creation of materials designed to possess enhanced properties and facilitate their production and application. The implementation of a Rapid Scan technique on a FT-IR emissometer designed to allow the observation of materials under extreme temperature conditions allows following the liquid to solid-state phase transition mechanisms through time-resolved emissivity spectra acquired at a speed of 20 spectra per second. The cooling rate of the material can be modified by controlling the laser-heating system. This technique has been validated on SrAl2Si2O8 feldspar, a material which displays structural disorder. The technique is sufficiently accurate to determine small changes in the linewidths of spectra obtained at different cooling rates, suggesting that structural order is increased at slower cooling speeds and confirming the Al/Si ordering dependence on thermal history.

Pr 2 NiO (4+δ) coatings of rare earth nickelate oxide were prepared through RF magnetron co-sputtering, combined with an appropriate heat treatment. The study focused on optimizing the growth conditions to enhance the thermal emittance of the coatings, taking into account the influence of thickness and roughness. The research findings revealed interesting insights. Firstly, by analyzing room temperature infrared reflectivity and studying the temperature dependence of the normal spectral emittance in the range of 500 cm −1 to 5500 cm −1 , it was observed that the total emittance increased as the coating thickness increased. However, this increase tended to approach a saturation value at higher thicknesses. Additionally, the study demonstrated that a coating thickness of 2.8 μm was sufficient to effectively shield the substrate's infrared thermal response. This suggests the potential application of these coatings for thermal management purposes. Furthermore, the influence of roughness on the emittance was predominantly observed in the spectral range of 1200 cm −1 to 3600 cm −1 . This finding highlights the importance of considering surface roughness when designing coatings for optimal thermal properties. In summary, the research provided valuable insights into the growth conditions and the impact of thickness and roughness on the thermal emittance of Pr 2 NiO 4+δ coatings. These findings contribute to the development of improved materials for thermal management and related applications.

A new methodology allowing real time observation of materials during their cooling, from the molten state to low temperature has been developed. This possibility originates from the implementation of a Rapid Scan feature on a FT-IR emissometer designed to probe materials submitted to extreme temperature conditions. Original time-resolved emissivity dependence during the phase transition are reported for the first time. The resulting out of equilibrium, dynamic, new data have been compared to the equilibrium, static, classical measurements to demonstrate the reliability of the new technique on two reference samples (Al2O3 and SiO2). The proposed method has high possibilities to be applied to different materials to enable the observation of fast structural transformations during liquid to solid phase change through the evolution of the dielectric function.

We study structural and transport properties of different eutectic mixtures of molten carbonate used for the capture and valorization of CO2. Different techniques, such as NMR, PFG NMR, and electrical impedancemetry, were used to study Li2CO3-Na2CO3 (52:48%mol), Li2CO3-K2CO3 (62:38%mol), Li2CO3-K2CO3 (40:60%mol), and Li2CO3-Na2CO3-K2CO3 (43.5:31.5:25%mol) compositions at high temperature. The NMR measurements confirmed only the presence of anionic species CO32-. No effect of composition or temperature on speciation was detected. From electrical conductivity and self-diffusion coefficients measurements, we have shown that the electrical conductivity of carbonates not only depends on the radius of the cations, but also depends on the electrostatic interaction between ions. With the addition of K2CO3 in the carbonate mixture, the interaction between the charge carriers present in the liquid increases and results in a decrease of electrical conductivity. We have shown that the high solubility of CO2 in compositions with high lithium carbonate content is associated with a high mobility of Li+ cations.

A better understanding and use of molten carbonate fuel cells (MCFCs) requires more detailed consideration on transport properties in melt. The combination of different methodological developments can be one solution to improve our comprehension. Here we present 23Na and 7Li self-diffusion coefficients measured by pulsed field gradient (PFG) NMR technique combined with electrical conductivity obtained by a 4-electrode set up, in the eutectic mixture Li2CO3-Na2CO3 (52:48 %mol) at high temperature (up to 1050 K), and under pure CO2 atmosphere. The results were compared with known experimental data from literature obtained by radiotracers techniques and 2-electrode set up and also with some calculations of the transport properties. ? 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

A computer controlled circular turntable equipped with a blackbody reference and an integrated axisymmetric heating system based on a CO2 laser is at the heart of the reported device. It allows performing emittance measurements in the spectral domain ranging from far infrared up to visible light and in a wide range of temperature. The apparatus includes two spectrometers and was built to achieve optimal experimental conditions of measurement, i.e. environmental stability and single optical path for the acquisition of the thermal fluxes. The specific design of the apparatus is firstly described; applied procedures for the characterization of the blackbody reference, laser heating and the retrieval of the emittance spectra are given after. Finally measurements obtained for ruby, NdGaO3 and platinum are presented to illustrate the capacities of the apparatus. (C) 2015 Elsevier B.V. All rights reserved.