[en] The ternary borate systems Na₂O-Ln₂O₃-B₂O₃ (Ln = La, Nd) have been investigated in view of obtaining high-neodymium-concentration materials with weak concentration quenching. A ternary phase of composition Na₃Ln(BO₃)₂ (Ln = La, Nd) has been found. It crystallizes in the monoclinic space group P2₁/c. The structure has been determined for Na₃Nd(BO₃)₂. A full-matrix least-squares refinement led to R = 0.040. The structure is formed by isolated BO₃ triangles held together by the neodymium and sodium ions. The rare-earth atoms have a complex eightfold coordination in a covalent BO₃ matrix

[en] Specific features of cryochemical reactions of transition metal atoms, small clusters, complexes and nanoparticles are considered. New phenomena that arise in nano- and subnanoscale systems at low temperatures are analysed. It is shown that the competition between self-assembly processes of metal atoms and reactions of metal aggregates of different size with organic and inorganic reagents determines the chemical nature and properties of the intermediate and final products. Special attention is paid to the analysis of size effects caused by the dependence of the reactivity of metal clusters and nanoparticles on the number of constituent atoms. Prospects for the use of competitive cryochemical reactions are discussed.

[en] Thanks to infrared thermography, we have studied the mechanisms of CO₂ capture by solid adsorbents (CO₂ capture via gas adsorption on various types of porous substrates) to better understand the physico-chemical mechanisms that control CO₂-surface interactions. In order to develop in the future an efficient process for post-combustion CO₂ capture, it is necessary to quantify the energy of adsorption of the gas on the adsorbent (exothermic process). The released heat (heat of adsorption) is a key parameter for the choice of materials and for the design of capture processes. Infrared thermography is used, at first approach, to detect the temperature fields on a thin-layer of adsorbent during CO₂ adsorption. An analytical heat transfer model was developed to evaluate the adsorption heat flux and to estimate, via an inverse technique, the heat of adsorption. The main originality of our method is to estimate heat losses directly from the heat generated during the adsorption process. Then, the estimated heat loss is taken for an a posteriori calculation of the adsorption heat flux. Finally, the heat of adsorption may be estimated. The interest in using infrared thermography is also its ability to quickly change the experimental setup, for example, to switch from the adsorbent thin-layer to the adsorbent bed configuration. We present the first results tempting to link the thin-layer data to the propagation speed of the thermal front in a milli-fluidics adsorption bed, also observed by IR thermography. (authors)