THE FACT FTsalt SALT DATABASES

 

The FTsalt solution database (FTsalt53soln.sdc) contains salt solutions evaluated/optimized by the FACT group. The FTsalt compound database (FTsalt53base.cdb) contains all stoichiometric solid and liquid salts evaluated/optimized by the FACT group to be thermodynamically consistent with the FTsalt solution database. When the gas phase needs to be included for the calculations (such as for AlCl3-containing systems owing to the volatility of AlCl3), the FactPS compound database must be connected, and all gaseous species from this database must be selected. Note that a density model is available for some molten salt systems.

 

The salt databases have been under development for over 40 years. During the period 2000-2003, major additions and modifications were made as part of the FACT Database Consortium Project with funding from the Natural Sciences and Engineering Research Council of Canada and 15 industries (Noranda, INCO, Teck Cominco, Rio Tinto, Alcoa, Shell, Corning, Dupont, Pechiney, St. Gobain Recherche, Schott Glas, Sintef, Norsk Hydro, Mintek, IIS Materials.)

 

Note that data for the system AlF3-NaF-CaF2-LiF-MgF2-Al2O3 are found in the FThall databases and for the entire system Na-K-S-C-O-Cl-H in the FTpulp database.

 

 

                                   Systems and Components

 

The new FTsalt 7.3 database has been completely restructured, resulting in a more accurate description for many of the solid solutions. The structure, the Pearson notation and the space group are now displayed for most solid compounds and most solid solutions. Most solid solutions have been modified. In the previous FTsalt database, the Rocksalt-FCC-B1 solid solution (i.e. NaCl-KCl-RbCl…NaF-LiF…NaOH…) was divided into many differently named solution models without common intersolubility. Now, in FTsalt 7.3 all the rocksalt solutions are merged into one FCC-B1 solution (rocksalt), which includes hydrides, fluorides, chlorides, bromides, iodides, acetylides, hydroxides and nitrates (with several oxides) of Li, Na, K, Rb, Cs, with solubilities of Mg, Ca, Sr and Ba. The minor solubility of the transition metals and Ag have also been added to the rocksalt solution. Similar efforts have been made in merging solid solutions of the BCC-B2 CsCl structure, sphalerite (B3) and wurtzite (B4). The fluoride CaF2-FCC-C1 solid solution now includes Mg, Ca, Sr and Ba salts (fluorides, chlorides, hydrides, and oxides). A new antifluorite solution has been added with Li, Na, K, Rb, Cs, Ag, Cu as cations, and O, S and C2 as anions. Several MX2 solid solutions have also been added (Strukturbericht C4, C5, C6, C7, C21, C23 and C35). The single perovskite phase PRVK of the type AMX3 (A = alkali cation; M = divalent cation; X = Cl, F), existing in the previous database, has been replaced by four different perovskite phases : E21_ (cubic), oP20 (orthorhombic), hR30 (NaMgCl3 - ilmenite), and hP30 (hexagonal).

 

The FTsalt databases contain data for pure salts and salt solutions of 27 main cations (Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Mn, Al, Fe(II), Fe(III), Co, Ni, Zn, Pb, La, Ce, Th, U(III), U(IV), Pu(III), Pu(IV), Cr(II), Cr(III), Mo(V)) and 8 main anions (F, Cl, Br, I, NO3, OH, CO3, SO4)  (as well as for dilute solutions of O2- and OH- in the molten salt phase.) Although calculations are permitted for pure oxide systems, only dilute solutions of O2- in the molten salt phase should be considered. For pure oxide systems, please use the FToxid databases. Not all binary and ternary sub-systems have been evaluated and optimized, nor are all composition ranges covered. Sub-systems which have not been evaluated and optimized have been assumed ideal or have been approximated. The sub-systems and composition ranges which have been evaluated and optimized are described in the following. The most accurate calculations will be obtained in or near these sub-systems and composition ranges.

 

Note that when the properties of a multicomponent salt solution are approximated by means of a model from the optimized model parameters for its sub-systems, the approximation will be more accurate in the case of a common-cation or common-anion system than in the case of a reciprocal solution. (A reciprocal solution is one containing 2 or more cations and 2 or more anions.) For example, an estimation of the properties of a molten ternary common-anion chloride system ACl-BCl-CCl (abbreviated A,B,C//Cl) from optimized model parameters for its binary sub-systems (ACl-BCl, ACl-CCl and BCl-CCl) will in general be more precise than an estimation of the properties of a molten ternary reciprocal salt solution ACl-BCl-AF-BF (abbreviated A,B//F,Cl) from the optimized model parameters of its binary common-ion sub-systems (ACl-BCl, AF-BF, ACl-AF and BCl-BF).

 

Lists corresponding to the various evaluated/optimized combinations of ions were entered for the following solutions :

- liquid SALT (10 different lists : SALTA, SALTB,…, SALTJ)

- solid solutions of the type A2MX4 (A = alkali, M = divalent cation, X = Cl, F) : tI14 (2 lists : tI14A, tI14B), cI28 (1 list : CI28A), and oP28 (4 different lists : oP28A,…, oP28D)

{No lists were required for oC14, H11a and oP14}

- perovskite phases AMX3 (A = alkali, M = divalent cation, X = Cl, F) : E21_ (3 different lists : E21_A, E21_B, E21_C), oP20 (3 different lists : oP20A, oP20B, oP20C), and hP30 (2 lists : hP30A, hP30B)

{No lists were required for hR30}

In order for the phase selection to be easier, no lists were entered for the remaining 69 solid solutions although not all combinations of the corresponding constituents were evaluated/optimized. For the solutions with “authorized” lists mentioned above (liquid SALT, tI14, cI28, oP28, E21_, oP20, and hP30), the solutions SALT?, …, hP30? may be selected instead of the “authorized” solutions SALTA, SALTB,…, hP30A, hP30B, thus permitting larger combinations of ions to be considered for the calculations. However, the resulting calculations will be less accurate and the following precautions must always be taken owing to the use of a model with more than one sublattice for these various phases :

- liquid SALT (one cationic sublattice & one anionic sublattice) : the selected constituents must correspond to all cation/anion combinations of a set of cations A, B,… and a set of anions X, Y,…

- solid solutions of the type A2MX4 and AMX3 (two cationic sublattices & one anionic sublattice) : the selected constituents must correspond to all alkali cation/divalent cation/halide anion (Cl and/or F) combinations of a set of alkali cations (Li, Na, K,…), of a set of divalent cations (Mg, Mn,…), and of one or two halide anions (Cl, F)

 

Several systems not included in the current lists of constituents (but accessible through the “?” solutions) have been evaluated/optimized based on the available phase diagram data from the literature or on chemically similar systems for which data were available (when data were lacking). New lists of constituents will be added in the future.

 

Also, some solid solutions involving some cations and/or anions which are not yet included in the SALT liquid solution have been added. The thermodynamic evaluation and optimization of the corresponding systems will be completed in the future.

 

In general, to perform calculations for a given system in the Equilib or Phase Diagram modules, select all possible solutions and all pure solid compounds from the FTsalt databases. (The pure liquids are not required since they already appear as components in the liquid SALT solution.) For the solutions with “authorized” lists (liquid SALT; solid solutions tI14, cI28, oP28, E21_, oP20, and hP30), only one solution (A, B, … or ?) must (and can) be selected. Please check the list of constituents (by right-clicking on the full name of the solution) in order to make the proper choice. If the gas phase is required (such as for AlCl3-containing systems), select also all gaseous species from the FactPS compound database. In order to reproduce the calculated phase diagrams in the Phase Diagram module, the pure solid compounds from the FactPS compound database must not be selected, with the exception of solid Fe for the FeCl2-containing systems (i.e. reducing conditions). Also, a custom selection (i.e. removing 1 or more solid solutions which do not form and/or removing some “end-members” inside the B1 - rocksalt solid solution) might be required to facilitate the convergence of the calculations for a few systems, such as NaOH - Na2SO4. Please check the phase selection in the corresponding “Phas.dat” files in the Phase Diagram module. In the Equilib module, if the gas phase is required, select all gaseous species from the FactPS compound database. If some pure solid compounds are present in the FactPS compound database but not in the FTsalt compound database, you might select them for the calculations but all excluded pure solid compounds (identified with an “X”) must not be selected.

 

Note that volumetric properties (density) as a function of temperature were entered for most of the pure liquids in the SALT liquid solution of the FTsalt database.  Moreover, a density model (taking into account excess volume upon mixing) is available for the NaCl-KCl-MgCl2-CaCl2, LiF-NaF-KF-MgF2-CaF2 and NaCl-KCl-ZnCl2 molten salt systems. Approximate density calculations may be performed for larger systems such as Li, Na, K, Mg, Ca // Cl, F : all binary common-cation systems of the type LiCl-LiF, MgCl2-MgF2,… and all LiCl-based chloride binary systems of the type LiCl-NaCl, LiCl-MgCl2,… are then assumed to be ideal (in terms of the volumetric properties).

In order to perform density calculations for the SALT liquid solution, the following procedure must be followed : in the Menu Window of Equilib, select the liquid solution FTsalt-SALTA (for LiF-NaF-KF-MgF2-CaF2 or NaCl-KCl-MgCl2-CaCl2) or FTsalt-SALTI (for NaCl-KCl-ZnCl2), and check the box “include molar volume data and physical properties data”. In the Results Window, the density value (in gram∙cm-3) calculated from the model is displayed (in parentheses) at the 2nd line of the block corresponding to the liquid phase. A system density (in gram∙cm-3) that takes into account the available density data for all phases at equilibrium (liquid + 1 or more solid phases) is displayed below the integral property table.

 

System Li,Na,K,Mg,Ca,Sr,Ba//Cl,F  (SALTA)

Evaluated and optimized at all compositions including all ternary reciprocal systems, with the exception of the Ba-containing reciprocal systems (which are only predicted from the model parameters for the common-ion binary sub-systems).

[3002, 3007, 3008, 3009, 3010, 3011, 3036, 3039].

Density model available for the NaCl-KCl-MgCl2-CaCl2 and LiF-NaF-KF-MgF2-CaF2 molten salt systems [3025, 3026, 3032].

 

System Li,Na,K,Mg,Ca,Mn,Fe(II),Fe(III),Co,Ni,Al//Cl  (SALTB & SALTC)

Molten chloride solution evaluated and optimized at all compositions [3002, 3008, 3013, 3014, 3015, 3016]. (Note that the 2 binary terminal solid solutions in the AlCl3-FeCl3 system remain to be optimized.)

Density model available for the NaCl-KCl-MgCl2-CaCl2 molten salt system [3026].

 

System Li,Na,K,Rb,Cs,Mg,Ca,Sr,Ba//Cl  (SALTD)

Molten chloride system evaluated and optimized at all compositions [3002, 3007, 3008, 3011].

Density model available for the NaCl-KCl-MgCl2-CaCl2 molten salt system [3026].

 

System Li,Na,K,Rb,Cs//F,Cl,Br,I,NO3,OH  (SALTE)

All common-ion binary systems (AX-AY and AX-BX) have been evaluated and optimized, with the exception of: LiI-LiNO3, RbF-RbNO3, RbF-RbOH, RbCl-RbNO3, RbBr-RbOH, RbI-RbNO3, RbI-RbOH, CsF-CsOH, CsCl-CsOH, CsBr-CsOH, CsI-CsOH and CsI-CsNO3 for which ideal liquid solutions are assumed.

All ternary common-ion systems (AX-BX-CX and AX-AY-AZ) of the Li,Na,K,Rb,Cs//F,Cl,Br,I sub-system have been evaluated and optimized.

Reciprocal ternary systems (those containing two cations and two anions) have been optimized only for fluorides and chlorides of Li, Na and K. Other reciprocal ternary interactions are estimated. Hence, calculations for most multicomponent common-ion systems should be good, but calculations for multicomponent reciprocal systems (containing 2 or more cations and 2 or more anions) will not be as good if any of Rb, Cs, Br, I, NO3 or OH are present [3002, 3004, 3006, 3017].

 

System Li,Na,K//F,Cl,NO3,OH,SO4,CO3  (SALTF)

All common-ion binary systems (AX-AY and AX-BX) but no ternary common-ion systems (AX-BX-CX and AX-AY-AZ) have been evaluated and optimized except LiF-NaF-KF and LiCl-NaCl-KCl.

The reciprocal ternary systems (those containing two cations and two anions) that have been optimized are: the fluorides and chlorides of Li, Na and K; Na,K//Cl,CO3; Na,K//Cl,SO4 and Na,K//CO3,SO4. Other reciprocal ternary interactions are estimated. Hence, calculations for multicomponent common-ion systems should be good, but calculations for multicomponent reciprocal systems (containing 2 or more cations and 2 or more anions) will usually not be as good if any of NO3, OH, SO4 or CO3 are present [3002, 3003, 3004, 3005, 3027].

 

System Li,Na,K,Rb,Cs,La,Ce//Cl  (SALTG)

Molten chloride solution. Limited available data (mainly for binary systems) have been evaluated and optimized [3002, 3008, 3018].

 

System Na,K,Ca,Pb//Cl  (SALTH)

Molten chloride solution optimized and evaluated (mainly for binary systems when PbCl2 is involved) [3002, 3008, 3019].

 

System Na,K,Mg,Ca,Al,Zn//Cl  (SALTI)

Molten chloride solution optimized and evaluated (mainly for binary systems when ZnCl2 is involved) [3002, 3008, 3015, 3016, 3038].

Density model available for the NaCl-KCl-MgCl2-CaCl2 and NaCl-KCl-ZnCl2 molten salt systems [3026, 3045].

 

System Li,Th,U(III),U(IV),Pu(III),Pu(IV),Cr(II),Cr(III),Ni(II),Mo(V)//F  (SALTJ)

Molten fluoride solution optimized and evaluated (dedicated to the LiF-ThF4-UF3-UF4-PuF3-PuF4 system for the so-called Molten Salt Nuclear Reactors).

In order to evaluate the oxido-reduction behaviour of the molten salt solution contained in Ni-Cr-based alloys, the components CrF2, CrF3, NiF2 and MoF5 were added to the liquid phase as ideal components (i.e. their Gibbs energies g0liquid are included, but these components mix ideally with all other components).

 

Dissolution of O2- and OH- in dilute solution in molten chlorides and/or fluorides

has been modeled and optimized for composition regions where data are available.  For details, see the detailed descriptions of FTsalt-SALTA, FTsalt-SALTB and FTsalt-SALTD under “Description of solutions” in this menu.

 

 

 

Phases

 

For complete descriptions of all solution phases, click on “Description of solutions” in this menu.

 

 

                                  The Molten Salt Solution

 

The molten salt phase (SALT) contains the main components in the FTsalt databases. The Modified Quasichemical Model is used [1010, 1015, 1016, 1019, 1020, 1021, 1022], generally in the quadruplet approximation [1022] which takes account of short-range-ordering among first-nearest-neighbour cation-anion pairs and second-nearest-neighbour cation-cation and anion-anion pairs. When AlCl3 is a component, a distinction among 4-coordinated Al[3+] (Al tetra), 5-coordinated Al[3+] (Al penta) and dimeric Al2[6+] is made in the model. The 5-coordinated Al[3+] species (Al penta) was introduced only in order to be consistent with the model used for AlF3-based (cryolitic) systems in the FThall database. See detailed description of FTsalt-SALT by clicking on “Description of solutions” [3002, 3003, 3004, 3005, 3006, 3007, 3008, 3009, 3010, 3011, 3013, 3014, 3015, 3016, 3017, 3018, 3019, 3027, 3036, 3038, 3039].

 

 

                                      Solid Solutions

 

In general, for solid solution phases, a sublattice model is used, based on the Compound Energy Formalism [1026].  Estimation of multicomponent properties from binary model parameters is generally performed using a generalized Kohler-Toop technique [1016, 1019].

 

Solid Solutions of the type A2MX4 : tI14, oC14, H11a, cI28, oP14 & oP28

Solid solutions with A = Li,Na,K,Rb,Cs on one cationic sublattice, M = Mg,Ca,Mn,Fe(II),Co,Ni,Sr,Ba on the second cationic sublattice, and X = F,Cl on the anionic sublattice. The following combinations of components have been optimized over their entire composition ranges :

 

(Li,Na,K)2[Mg,Ca,Mn,Fe(II),Co,Ni]Cl4

(Li,Na,K,Rb,Cs)2[Mg,Ca,Sr,Ba]Cl4

(Li,Na,K)2[Mg,Ca]{F,Cl}4

 

See detailed description of FTsalt-tI14, FTsalt-oC14, FTsalt-H11a, FTsalt-cI28, FTsalt-oP14 and FTsalt-oP28 by clicking on “Description of solutions”.

 

Perovskite solid solutions AMX3 : E21_ (cubic), oP20 (orthorhombic), hR30 (NaMgCl3 - ilmenite) & hP30 (hexagonal)

Solid solutions with A = Li,Na,K,Rb,Cs on one cationic sublattice,

M = Mg,Ca,Mn,Fe(II),Co,Ni,Sr,Ba on the second cationic sublattice, and X = F,Cl on the anionic sublattice. The following combinations of components have been optimized over their entire composition ranges :

 

(Li,Na,K)[Mg,Ca,Mn,Fe(II),Co,Ni]Cl3

(Li,Na,K,Rb,Cs)[Mg,Ca,Sr,Ba]Cl3

(Li,Na,K)[Mg,Ca,Sr,Ba]{F,Cl}3

 

See detailed description of FTsalt-E21_, FTsalt-oP20, FTsalt-hR30 and FTsalt-hP30 by clicking on “Description of solutions”.

 

Other solid solutions

69 additional evaluated and optimized solid solutions are available in the FTsalt solution database. These are summarized under “List of compounds and solutions” and detailed descriptions are provided under “Description of solutions.”

 

                               Stoichiometric Solid Salts

Evaluated and optimized properties for over 380 stoichiometric solid salts are found in the FTsalt compound database. For a list, see “List of compounds and solutions.”