ORALS

SESSION: MoltenTueAM-R3	Fehrmann International Symposium on Sustainable Molten Salt and Ionic Liquid Processing (6th Intl. Symp. on Sustainable Molten Salt and Ionic Liquid Processing)
Tue Nov, 6 2018 / Room: Bossa (150/3rd)
Session Chairs: Robin Rogers; Session Monitor: TBA

12:35: [MoltenTueAM04]
Topological Forecast of 4D T-x-y-z Diagram Li,Na,Rb,La||F
Vasily Lutsyk¹ ; Anna Zelenaya¹ ; Maria Parfenova² ; ¹Institute of Physical Materials Science SB RAS, Ulan-Ude, Russian Federation; ²Tomsk State University of Control Systems and Radio-electronics, Tomsk, Russian Federation;
Paper Id: 120 [Abstract]

Interest in systems with fluoride metals is due to the fact that they have been considered as a potential component for nuclear reactor fuel in molten salts. Three ternary systems of Li,Na,Rb||F, Li,Rb,La||F and Na,Rb,La||F on the boundary of quaternary system Li,Na,Rb,La||F have been analyzed. Model for the 4th boundary Na,Li,La||F was built earlier [1]. Li,Na,Rb||F has the simplest structure. Its eutectic type is complicated by the compound R=LiRbF₂, decaying in the solid phase, and is characterized by two invariant equilibria: eutectic one and decomposing of R (dot Y). Space model includes 3 liquidus surfaces, 3 - solidus, 10 - solvus, 22 - ruled ones, and 2 horizontal complexes at temperatures of E and Y, and has 4 monophase regions (А, В, С, R), 9 - 2-phase (L+A, L+В, L+С, A+B, A+C, B+C, A+R, B+R, C+R) and 7 - 3-phase ones (L+A+В, L+A+C, L+B+C, A+B+C, A+C+R, A+B+R, B+C+R). System Li,Rb,La||F is complicated by 5 binary compounds: R₁=LiRbF₂ - with the exotermic decaying, and 4 incongruently melting R₂=Rb₃LaF₆, R₃=Rb₂LaF₅, R₄=RbLaF₃, R₅=RbLa₂F₇. Compounds R3, R5 have endothermic decay and exist in the short temperature interval. Space model consists of 7 liquidus surfaces, 31 ruled surfaces, 6 horizontal complexes and includes 10 2-phase regions (L+A, L+B, L+C, L+R2, L+R3, L+R4, L+R5, R1+R2, A+R2, A+R4) and 16 3-phase regions (L+A+B, L+A+C, L+A+R2, L+A+R4, L+B+R2, L+C+R4, L+C+R5, L+R2+R3, L+R2+R4, L+R3+R4, L+R4+R5, A+R1+R2, A+B+R2, A+R2+R4, A+C+R4, B+R1+R2). 2-phase regions R1+R2, A+R2, A+R4 have a degenerated structure in the form of vertical planes. System Li,Rb,La||F has a similar structure, but is sophisticated by the additional liquidus surface of R1=NaLaF₄. As a result, there are 3 invariant equilibria, 8 liquidus surfaces, 35 - rules ones and 6 horizontal complexes on the boundary of 28 phase regions (L+A, L+B, L+C, L+R1, L+R2, L+R3, L+R4, L+R5, A+R2, A+R4, R1+R4, L+A+B, L+A+R1, L+A+R2, L+A+R4, L+B+R2, L+C+R1, L+C+R4, L+C+R5, L+R1+R4, L+R2+R3, L+R2+R4, L+R3+R4, L+R4+R5, A+R1+R2, A+R2+R4, A+R1+R4, R1+R4+C). Concentration fields in the 4 ternary systems with the different trajectories of phases have been analyzed [2-3]. 4 ternary systems are used to forecast a topological structure of T-x-y-z diagram Li,Na,Rb,La||F [4] with 6 binary compounds: R₁=LiRbF₂, R₂=NaLaF₄, R₃=Rb₃LaF₆, R₄=Rb₂LaF₅, R₅=RbLaF₄, R₆=RbLa₂F₇ (R1 decays in solid, R2-R6 - with incongruently melting, and R3, R5 with endothermic decaying). In the ternary systems there are 14 invariant equilibria. For T-x-y-z diagram Li,Na,Rb,La||F it is forecasted 4 invariant 5-phase equilibria with 9 liquidus hypersurfaces.

References:
[1] R.N. Savchuk, N.V. Faidyuk, A.A. Omelchuk, V.I. Lutsyk, A.E. Zelenaya, Journal of Inorganic Chemistry, 59 (2014) 780-785. (In Russian)
[2] V. Lutsyk, A. Zelenaya, Journal of Physics: Conference Series, 790 (2017), 012020.
[3] Y.V. Pogorenko, R.M. Pshenychnyi, V.I. Lutsyk, A.O. Omel'chuk, IOP Conf. Series: Materials Sci. and Eng., 175 (2017), 012039.
[4] V.I. Lutsyk, A.E. Zelenaya, Journal of Physics: Conference Series, 790 (2017), 012020.