Assessment of thermodynamic data for CuCrO2 delafossite from calorimetric measurements

A detailed investigation of the thermodynamic properties of delafossite CuCrO2 was carried out by experimental methods on synthetic CuCrO2 delafossite samples (differential scanning calorimetry from ambient to 871 K and drop calorimetry from 823 to 1123 K) and theoretical methods (density functional theory). Based on these data and available literature (low temperature heat capacity measurements and calculations, high temperature emf data), we propose, for the first time, a full set of thermodynamic data for the phase CuCrO2. Our selection comes to: ΔfH°298(CuCrO2) = −670.8 ± 1.3 kJ mol−1, S°298(CuCrO2) = 88.9 J K−1, and cp°(T)=1.02564.102-2.87159.107 T-3-1.28542.105 T-1.5 (298 < T < 1300 K)

Stresses in thin Au films on γ alumina

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Transformation of a Double Focusing B-E Mass Spectrometer for Multiple-Cell Knudsen Effusion Part I: Scientific Concepts

International audienceKnudsen Effusion Mass Spectrometry (KEMS) is a powerful method in the field of experimental thermodynamics at high temperatures. Since 2005, the long term project of transforming and upgrading a double-focusing VG Micromass 54-38K mass spectrometer for multiple-cell effusion has started at the IM2NP in Marseille/France. The scientific concepts underlying the transformation are presented in this first paper. The molecular beam effusing from the Knudsen cells must be sampled under restricted collimation conditions. The resulting geometric constraints are taken into account in the design of the large main vacuum chamber necessary to house a multiple-cell effusion furnace. Decrease of the molecular transmission between the cell and the ionization source needs to be counterbalanced by an increase in the sensitivity of the ionization source. Other modifications of the instrument are reviewed. The first tests and results will be the subject of a second paper to be published. Overview of the project The mass spectrometer, given to us by J. Drowart after he retired from the Université Libre de Bruxelles, is a double focusing 54-38K model manufactured by VG micromass. The analyzer has a BE geometry in which a magnetic sector, with a radius of 27 cm and 95°, precedes an electrostatic sector of 38.1 cm (15 ") radius, 81.5°. The ionizer is an electron impact source. The spectrometer is not equipped with any effusion device. The project is to adapt this spectrometer for activity measurements up to 2500 K by the multiple-cell technique according to the concepts developed by C. Chatillon and his coworkers (1, 2, 3) at the CNRS-SIMAP laboratory in Grenoble, France. Concretely, it implies that the molecular beams effusing from the Knudsen cells must be sampled under restricted collimation conditions. The resulting geometric constraints are taken into account in the design of the large main vacuum chamber necessary to house a four-cell effusion furnace. Moreover, decrease in the molecular transmission between the cell and the ionization source needs to be counterbalanced by an increase in the sensitivity of the ionization source. The ion optics between the entrance and the exit slits of the analyzer is not modified. 10.1149/04601.0127ecst ©The Electrochemical Society ECS Transactions, 46 (1) 127-141 (2013) 127) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.218.248.200 Downloaded on 2015-04-12 to I

DSC investigation of phase equilibria in the Bi-Pb-Sb system

International audienceTwo sections at X-Bi/X-Pb = 2/3 and X-Pb = 0.6 atomic fraction of the Bi-Pb-Sb system are analysed by Differential Scanning Calorimetry. The graphical representations of both sections are drawn in agreement with the binary side systems and the phase boundaries determined from DSC thermograms suit well above T = 373.2 K. A transitory peritectic reaction is observed at T = (445.2 +/- 0.5) K. Isothermal sections at 445.25 K and 273.15 K are proposed. (C) 2016 Elsevier Ltd

Contribution to thermochemical studies of 0.8[xB2O3–(1−x)SiO2]–0.2Na2O glasses

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Calorimetric Determination of the Formation Enthalpies of Cs Polymolybdates at 298.15 K and 0.1 MPa

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Enthalpies of formation of the La–Zn compounds between 298K and 910K

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Determination of solution enthalpy of zirconium in liquid aluminum

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Experimental study and thermodynamic modelling of the Ag-Cd-In system

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Revisiting the thermodynamic properties of the ZrCr2 Laves phases by combined approach using experimental and simulation methods

International audienceA comprehensive study of ZrCr2 Laves phases is important for both fundamental research and technological applications. The ZrCr2 compound is a typical precipitate observed in Zr-based alloys including the newly developed Cr-coated Zr cladding known as Accident Tolerant Fuel cladding. The brittle behavior of the Laves phases and the low melting point at the interface zone between the precipitates and the Zr matrix are considered as governing the thermomechanical behaviors of these newly developed nuclear fuel claddings for normal operating conditions but more dramatically in case of Loss Of Coolant Accident (LOCA) conditions. The aim of the present study is to investigate the various ZrCr2 Laves polymorphs and their thermodynamic features particularly where conflicts exist in the literature. Based on diffraction experiments of annealed samples, it has been established that the transformation from the C14 high-temperature form to the C15 low-temperature form is of displacive nature without the C36 polymorph forming as an intermediate phase. The stable and metastable domains of C14 and C15 and their thermodynamic properties have been determined. The specific heat of both C14 and C15 types was measured over a wide range of temperatures from 2 to 1063 K by coupling relaxation calorimetry and DSC. The experimental data were fitted using a modified Einstein model. The room temperature entropies of the C14 and C15 phases were evaluated. The enthalpy of formation was measured for the first time using drop solution calorimetry in liquid Al at 1173 K in a Tian–Calvet calorimeter. The experimental value is in good agreement with Density Functional Theory (DFT) calculations. Finally, all these new results are discussed regarding the abundant literature on the ZrCr2 Laves phases