Thermodynamics of Materials in Extreme Environments: Thermodynamics of Nuclear Materials and Minerals
Sponsored by: ACerS Basic Science Division, ACerS Energy Materials and Systems Division
Program Organizers: Xiaofeng Guo, Washington State University; Kristina Lilova, Arizona State University; Kyle Brinkman, Clemson University; Alexandra Navrotsky, Arizona State University; Jake Amoroso, Savannah River National Laboratory; Xingbo Liu, West Virginia University; Gustavo Costa, NASA Glenn Research Center
Monday 8:00 AM
October 18, 2021
Room: A221
Location: Greater Columbus Convention Center
Session Chair: Xiaofeng Guo, Washington State University; Kyle Brinkman, Clemson University
8:00 AM Introductory Comments
8:10 AM Invited
ACerS Navrotsky Award for Experimental Thermodynamics of Solids: Advancing Solar-Driven Thermochemical Fuel Production Using Nonstoichiometric Perovskites: Xin Qian1; 1Georgia Institute of Technology
Perovskite oxides are promising alternatives to state-of-the-art fluorite CeO2-δ in solar-driven thermochemical fuel production. Guided by computational insights, we explore the thermodynamic properties and water splitting efficacy of the perovskites SrTi0.5Mn0.5O3-δ (STM55) and CaTi0.5Mn0.5O3-δ (CTM55). While STM55 is cubic structure under all accessible values of oxygen non-stoichiometry (δ), CTM55 has an orthorhombic structure at small δ, and transforms to a cubic phase when δ ≥ 0.022. The cubic phases of both materials provide attractive combinations of moderate enthalpy, 200 – 250 kJ (mol-O)-1, and high entropy, ~ 150 J (mol-O)-1 K-1 at δ = 0.1. Using a water splitting cycle in which the materials are reduced at just 1350 °C (pO2, ~10-5 atm), remarkable hydrogen yields of 10 mL g-1 and 7.4 mL g-1 are achieved, respectively, for CTM55 and STM55. Comparison of the measured gas production profiles to those predicted for quasi-equilibrium behavior suggests that under most conditions, the fuel production rate is largely limited by thermodynamic rather than kinetic constraints.
8:55 AM
Thermodynamic Investigation of Multicomponent Chloride Molten Salts for Spent Fuel Processing: Liangyan Hao1; Soumya Sridar1; Elizabeth Sooby2; Wei Xiong1; 1University of Pittsburgh; 2University of Texas at San Antonio
Pyroprocessing has been developed to recycle uranium from spent fuels and thus reduce radioactive wastes. To effectively monitor the change of thermodynamic properties and liquidus temperature for the molten salt electrolyte with composition, a multicomponent thermodynamic database for the KCl-LiCl-NaCl-UCl3-LnCl3 (Ln=La, Nd, Pr) will be established. Based on the SGTE Substance Database, fifteen binary systems have been optimized to satisfactorily reproduce experimental phase equilibria and thermodynamic properties data. Short-range ordering present in the liquid phase was described by the two-sublattice ionic model. Thermal analysis was firstly performed to study the phase equilibria in the KCl-NaCl-UCl3 and LiCl-NaCl-UCl3 systems and support the thermodynamic modeling. The established multicomponent database will contribute to the development of advanced reactors, such as small modular reactors.
9:15 AM Invited
Energetics of Fe3O4 – FeAl2O4 Spinel Solid Solution: Alexandra Navrotsky1; 1Arizona State University
High temperature oxide melt solution calorimetry has been used to elucidate the energetics of Fe3O4 – FeAl2O4 solid solution. Conventional solid state reactions from constituent oxides were utilized to synthesize Fe(Al1-xFex)2O4 spinels. Due to oxygen sensitive Fe2+ in the spinel structure, the samples were synthesized under argon flow to minimize the oxidation during the synthesis. The enthalpies of formation from constituent oxides (ΔH°f,ox) and elements of the end members and the solid solutions were calculated from the drop solution enthalpies. The enthalpies of mixing of the Fe(Al1-xFex)2O4 system and the solvus were determined and the data will provide input for future CALPHAD assessments.