Mixing properties in the continuous solid solution of the system (CsNO3 + TlNO3) at T=473 K

International audiencePrevious work on the binary phase diagram (CsNO3 + TlNO3) showed, in particular, the existence of a continuous solid solution, CsxTl1-xNO3. It extends over the whole composition range between T = 430 K and T = 480 K. Mixing enthalpies of the solid solutions CsxTl1-xNO3 are measured at T = (473 +/- 1) K, for the first time, by using a drop calorimetric method. They exhibit a positive and asymmetrical deviation from ideality. (C) 2015 Elsevier Ltd. All rights reserved

Experimental study of phase equilibria in the (AgNO3+LiNO3+NaNO3) ternary system

International audienceSeven sections, in the ternary phase diagram (AgNO3 + LiNO3 + NaNO3) were studied at atmospheric pressure by means of differential thermal analysis (DTA) and differential scanning calorimetry (DSC): X(AgNO3) = 0.1 and 0.8, X(AgNO3)/X(LiNO3) = 3/2 and 2/3, X(LiNO3) = 0.2, and X(NaNO3) = 0.258 and 0.3. The results exhibit two invariant reactions: a eutectoid at T = 380 K and a eutectic at T = 440 K. (c) 2013 Elsevier Ltd. All rights reserved

Thermodynamic modeling of the AgNO3–CsNO3–NaNO3 ternary system

International audienceBy means of an optimization procedure, the AgNO3–CsNO3–NaNO3 ternary system has been assessed. The mixing enthalpies in the ternary system and the results derived from thermodynamic descriptions for the three limiting binary systems are used. For the AgNO3–NaNO3 and CsNO3–NaNO3 systems, optimized Gibbs energy expressions were taken from the literature. An assessment of the binary AgNO3–CsNO3 system based on the available experimental data is presented in this paper; the calculated phase diagram and thermodynamic functions agree well with experimental data. The parameters describing the Gibbs energies of all binary phases and the ternary liquid are used to predict the phase diagram of the AgNO3–CsNO3–NaNO3 syste

Experimental investigation and thermodynamic evaluation of the CsNO3-LiNO3-NaNO3 ternary system

International audienceThe alkali nitrate mixtures are promising phase change materials (PCMs) in the temperature range (373−573) K for the development of thermal storage systems. In this context, their thermochemical properties and phase diagrams which provide useful thermal information are needed for their better use. In the present paper, the mixtures based on cesium nitrate, lithium nitrate, and sodium nitrate are studied by both experimental and optimization techniques. Thus, a critical analysis of thermodynamic data from literature sources of the phases in the CsNO3-LiNO3-NaNO3 ternary system including the pure components is performed. Therefore, reliable phase change data (enthalpy and temperature) of pure nitrates CsNO3, LiNO3 and NaNO3 are proposed. In addition, by means of differential thermal analysis (DTA), the binary CsNO3-LiNO3 system and two vertical sections (= 1 and = 0.2) in the ternary CsNO3-LiNO3-NaNO3 system are investigated. X-ray diffraction (XRD) technique is also used to analyze phases in the CsNO3-LiNO3 binary system at room temperature. The CsNO3-LiNO3 binary system is characterized by a congruent equimolar compound Cs0.5Li0.5NO3 which appears at (334 ± 2) K. Two eutectic reactions are found at (445 ± 2) K and (435 ± 2) K, respectively. The system exhibits also a plateau at (427 ± 2) K corresponding to the polymorphic transition of CsNO3. The CsNO3-LiNO3-NaNO3 ternary system shows two ternary eutectic reactions at (408 ± 2) K and (405 ± 2) K, respectively. Combining our results with experimental data available in the literature, an optimization of the thermodynamic parameters in the ternary system is performed with the help of Calphad approach. A reasonable agreement between the calculated results and the experimental data is obtained