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• Several molten fluoride pseudo-ternary salt system densities were estimated. • The estimation is based on Redlich-Kister expansion and Muggianu interpolation. • This method generally outperforms estimation by additive molar volumes. • Some unmeasured pseudo-binary system densities were also estimated. The development of next-generation molten salt reactors relies on accurate knowledge of the thermophysical properties of the candidate coolant and fueled molten salts. These thermophysical properties include density, viscosity, thermal conductivity, and heat capacity. Because of difficulties in measuring thermophysical properties of molten salts, there are many gaps in the current state of thermophysical property knowledge of these salts, particularly those that contain actinides or beryllium. Therefore, leveraging modeling techniques to estimate unknown molten salt thermophysical properties and guide future experimental measurements has high value for the nuclear industry. In this study, the densities of molten fluoride pseudo-ternary salt systems, which are of interest to the nuclear industry, were estimated using Redlich-Kister expansion and Muggianu interpolation techniques. The pseudo-ternary systems considered for estimation in this study were NaF-LiF-ZrF 4 , LiF-BeF 2 -ZrF 4 , LiF-BeF 2 -ThF 4 , NaF-LiF-BeF 2 , NaF-KF-BeF 2 , NaF-ZrF 4 -UF 4 , and NaF-BeF 2 -UF 4. This Redlich-Kister estimation approach accounts for nonideal mixing behavior based on pseudo-binary subsystem interaction parameters determined from experimentally measured pseudo-binary system density data sets. The Redlich-Kister estimation was compared with the method of additive molar volumes, which assumes ideal mixing. The Redlich-Kister approach was also used to determine previously unknown binary and ternary interaction parameters based on experimentally measured density data sets for select pseudo-ternary salt systems. The results of this study show improvement in density estimation using the Redlich-Kister approach for all systems considered compared with estimation by additive molar volumes. Furthermore, this analysis allowed for the estimation of nonideal density behavior in experimentally unstudied ZrF 4 -UF 4 and BeF 2 -UF 4 , as well as the quantification of ternary interaction in NaF-LiF-ZrF 4 , NaF-BeF 2 -UF 4 , and NaF-ZrF 4 -UF 4. [ABSTRACT FROM AUTHOR]

• Thermal conductivity of molten eutectic LiF-NaF-KF is measured from 834 to 1195 K with the variable gap technique. • Thermal conductivity of LiF-NaF-KF is predicted with a kinetic theory derived model and equilibrium molecular dynamics. • Temperature dependence of the thermal conductivity of LiF-NaF-KF is discussed from an experimental and theoretical viewpoint. • Inconsistencies between experimental data on thermal conductivity of molten LiF-NaF-KF reported in literature are discussed. • Mapping of the thermal conductivity of LiF-NaF-KF is proposed in the entire range of temperature from 750 K to 1300 K. Molten salts are being proposed for numerous advanced energy applications, including advanced nuclear reactors, concentrating solar power plants, thermal energy storage, and fusion reactors. Accurate knowledge of the thermophysical properties of molten salts directly impact the performance of these energy systems and are essential for design and safety analyses. Thermal conductivity data for fluoride molten salts and mixtures are especially lacking. In this work, experimental measurements of thermal conductivity using the steady-state variable gap technique were performed on eutectic LiF-NaF-KF from 834 to 1195 K. The experiment accounts for radiative, convective, and conductive heat losses. In addition, theoretical and molecular dynamics models are used, from 750 K up to 1300 K, to estimate the thermal conductivity for comparison with the experimental results. The results of experiments show a weak negative deviation of thermal conductivity with temperature, unlike previous experimental results in the literature. The measured thermal conductivity magnitudes agree with the theoretical and molecular dynamics predictions, aside from the data above 1100 K, where heat losses and radiative errors are the most significant, having a 16% maximum deviation from theory. These experimental results provide new thermal conductivity data for the LiF-NaF-KF system and further validation of the predictive models. The theoretical model was used to map the composition and temperature dependent thermal conductivity of LiF-NaF-KF and the mapping's deviation from a linear additivity estimation of thermal conductivity. This mapping showed the highest deviations from linearity for KF-LiF rich mixtures and increasing deviation with temperature. Notably, the deviation from linearity near the LiF-NaF-KF eutectic composition was around 25%. [ABSTRACT FROM AUTHOR]

• Techniques used for the measurement of thermal conductivity are reviewed. • A steady state instrument designed to measure the thermal conductivity is presented along with the measurement theory. • Tested on helium and KNO 3 NaNO 3 molten salt from 300 °C to 500 °C. • Effects of convection and radiation were mitigated using this technique. • Conductive heat losses will need to be minimized to extend operability above 500 °C. High-temperature fluids such as molten salts, liquid metals, and gasses are being proposed for many advanced energy systems including thermal energy storage devices, concentrating solar plants, and advanced nuclear reactor designs. However, the chemical behavior and thermophysical properties of many of these fluids have not been well characterized, which hinders the design, modeling, safety analysis, and deployment of these systems. Thermal conductivity is a property that is especially limited by existing measurement capabilities, which are subject to errors caused by convection, material interaction, radiative heat transfer, and instrument degradation. Therefore, there is a lack of standard, systematic measurement techniques for high-temperature, reactive, and corrosive fluids. In this work, the development of a variable gap thermal conductivity measurement system is detailed. The system is designed to measure the thermal conductivity of highly corrosive and reactive fluids, and survive operation between 100 °C and 800 °C. The effects of convection are minimized by limiting the thickness of the specimen to thin sizes (<0.3 mm). Corrections for radiative heat transfer were included in the working equations to consider specimens with varying optical properties. The design, construction, instrumentation, operating principles, and data analysis techniques are discussed in detail. The system was tested up to 500 °C using helium gas and molten KNO 3 NaNO 3 to verify the measurement technique and determine the sources of error. At 300 and 400 °C KNO 3 NaNO 3 , results showed maximum relative error of 6% when compared to results in the literature. The helium results were within 13% of those in the literature at 300 and 400 °C. Higher errors were observed at 500 °C for both fluids, and the sources of these errors are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Allyl-palladium dithiocarbamate complexes, [Pd(allyl)(S2CNR2)], have been prepared from the addition of dithiocarbamate salts to [Pd(allyl)(μ-Cl)]2 and TGA and DSC studies have been carried out in order to assess their potential as MOCVD precursors to palladium sulfides. For comparison [(η3-C4H7)Pd(S2PPh2)] and [Pd(S2CNMeR)2] (R=Bu, Hex) have also been prepared and tested as precursors. The unsymmetrical dithiocarbamate complex, [(η3-C3H5)Pd(S2CNMeHex)], which has a melting point of 65°C was selected as the best single source precursor and thin films of predominantly Pd2.8S were deposited on glass slides. The crystal structures of [(η3-C4H7)Pd(S2CNMe2)], [(η3-C4H7)Pd(S2CNPr2)], [(η3-C4H7)Pd(S2PPh2)] and [Pd(S2CNMeBu)2] are reported. All except [(η3-C4H7)Pd(S2CNPr2)] show weak intermolecular S⋯H or Pd⋯H interactions. [Copyright &y& Elsevier]