1624

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2007, Vol. 52, No. 10, pp. 1624–1628. © Pleiades Publishing, Inc., 2007.Original Russian Text © T.V. Gubanova, I K. Garkushin, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 10, pp. 1726–1730.

TECHNIQUES AND MATERIALS

Differential thermal analysis (DTA) was used tostudy the title five-component system. A Pt–Pt/10Rhthermocouple served as the temperature gage. A KSP-4automated potentiometer was used as a recorder.Freshly calcined

Al

2

O

3

served as a reference. The cool-ing rate was 15 K/min. The temperature range of thestudy was

300–900°ë

. All compositions wereexpressed in molar percent; temperature, in degreescentigrade. The sample size was 0.2 g.

The starting chemicals (high purity grade

Li

2

SO

4

,chemically pure grade LiCl, analytical grade LiF, andpure grade

Li

2

MoO

4

) were calcined or fused (LiCl).Lithium metavanadate was synthesized by the proce-dure described in [1]. Reagent purity was monitoredusing X-ray powder diffraction (DRON-3,

Cu

K

α

radia-tion,

Ni

β

-filter).

The specific enthalpy of melting of the eutecticcomposition was determined by quantitative DTA. ADTA setup with thermocouples attached to the bottomof crucibles was used. Three cooling and three heatingcurves were recorded for the eutectic composition anda reference (

K

2

Cr

2

O

7

, polymorphic transition at

397°ë(125.2

±

7)

kJ/kg). DTA peak areas were determined inaccordance with the recommendations of the Interna-tional Confederation for Thermal Analysis and Calo-rimetry [2]. The specific enthalpy of melting was calcu-lated from [3]

(1)

Here,

∆

t

H

ref

is the specific enthalpy of phase transitionin the reference, with the transition temperature close tothat in the test composition, kJ/kg;

S

E

and

S

ref

are theDTA peak areas due to eutectic melting and the phasetransition in the reference, respectively; and

T

E

,

and

T

ref

are the melting temperature of the eutectic compositionand the phase-transition temperature in the reference,

∆mHE ∆tHref

SE

Sref--------

TE

T ref--------= , kJ/kg.

respectively, K. The final value of the enthalpy wasfound as the average of three measurements.

EXPERIMENTAL

Experimental design in the

LiF–LiCl–LiVO

3

–Li

2

SO

4

–Li

2

MO

4

system was carried out according to theprojective thermogravimetry rules [4]. Phase-transitionparameters for the individual compounds were takenfrom [5]. All two-, three-, and four-component systemsthat are subsystems of the LiF–LiCl–

LiVO

3

–Li

2

SO

4

–Li

2

MoO

4

system were studied in [1, 6–19]. In this study,we refined some parameters, namely, the melting tem-peratures and compositions of alloys at invariant pointsin the two- and three-component systems (table). Dataon the subsystems are displayed on the phase diagramof the five-component system.

For the experimental study of the five-componentsystem, we chose the 3D polythermal section

Ä

BCD

:

Ä

, [70.0% LiCl + 30.0% LiF];

B

, [70.0% LiCl + 30.0%Li

2

SO

4

];

C

, [70.0% LiCl + 30.0% Li

2

MoO

4

];

D

, [70.0%LiCl + 30.0% LiVO

3

] (Figs. 2, 3). Section

ABCD

ispositioned in the lithium chloride crystallization vol-ume, where the components have higher melt solubili-ties.

Proceeding from the positions of the projections ofthe invariant points in three- and four-component sys-tems in the region of the

ABCD

3D section, we chose2D polythermal section

abc

:

a,

[70.0% LiCl + 18.0%Li

2

SO

4

+ 12.0% LiF];

b

, [70.0% LiCl + 18.0% Li

2

SO

4

+12.0% Li

2

MoO

4

];

c

, [70.0% LiCl + 18.0% Li

2

SO

4

+12.0% LiVO

3

] (Figs. 3, 4). Then, 1D isopleth

KL

waschosen in this 2D section:

K

, [70.0% LiCl + 18.0%Li

2

SO

4

+ 7.2% Li

2

MoO

4

+ 4.8% LiF];

L

, [70.0% LiCl +18.0% Li

2

SO

4

+ 7.2% Li

2

MoO

4

+

4.8%

LiVO

3

](Fig. 5).

From the

KL

phase diagram, we determined , theprojection of the quintuple eutectic point, at which qua-

E*

LiF–LiCl–LiVO

3

–Li

2

SO

4

–Li

2

MoO

4

System

T. V. Gubanova and I. K. Garkushin

Samara State Technical University, Samara, Russia

Received November 30, 2006

Abstract

—Phase equilibria in the LiF–LiCl–LiVO

3

–Li

2

SO

4

–Li

2

MoO

4

system have been studied by differen-tial thermal analysis. The eutectic composition has been determined as follows (mol %): LiF, 17.4; LiCl, 42.0;LiVO

3

, 17.4; Li

2

SO

4

, 11.6; and Li

2

MoO

4

, 11.6, with the melting temperature equal to

363°ë

and the enthalpyof melting equal to (

284

±

7

) kJ/kg.

DOI:

10.1134/S0036023607100269

PHYSICOCHEMICAL ANALYSISOF INORGANIC SYSTEMS

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY

Vol. 52

No. 10

2007

LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 SYSTEM 1625

Characteristics of invariant points in two-, three-, and four-component subsystems

System Point typeComponent concentration*, mol %

Melting temperature, °C

1 2 3 4

LiF–LiCl [6] Eutectic 29.5 70.5 496

LiF–LiVO3 [7] " 23.0 77.0 573

LiF–Li2SO4 [6] Eutectic 41.0 59.0 530

Peritectic 26.0 74.0 575

LiF–Li2MoO4 [7] Eutectic 38.0 62.0 609

LiCl–Li2VO3 [7] " 55.0 45.0 491

LiCl–Li2SO4 [6] Eutectic 60.5 39.5 485

Peritectic 30.0 70.0 575

LiCl–Li2MoO4 [8] Eutectic 73.4 26.6 501

LiVO3–Li2SO4 [9] " 87.0 13.0 591

LiVO3–Li2MoO4 [10] " 73.0 27.0 533

Li2SO4–Li2MoO4 [6] " 62.0 38.0 581

LiF–LiCl–LiVO3 [11] " 17.0 50.8 32.2 463

LiF–LiCl–Li2SO4 [9] " 25.0 48.0 27.0 445

LiF–LiCl–Li2MoO4 [12] " 19.4 61.3 19.3 436

LiF–LiVO3–Li2SO4 [1] Eutectic 38.0 18.0 44.0 497

Peritectic 3.0 83.0 13.5 575

LiF–LiVO3–Li2MoO4 [13] Eutectic 18.0 53.0 29.0 493

LiF–Li2SO4–Li2MoO4 [1] Eutectic 30.1 43.4 26.5 501

Peritectic 1.5 61.0 37.5 575

LiCl–LiVO3–Li2SO4 [14] " 49.0 38.25 12.75 449

5.5 80.0 14.5 575

LiCl–LiVO3–Li2MoO4 [15] Eutectic 49.5 33.7 16.8 440

LiCl–Li2SO4–Li2MoO4 [16] Eutectic 58.5 23.6 17.9 445

Peritectic 7.5 55.0 37.0 575

LiVO3–Li2SO4–Li2MoO4 [13] Eutectic 63.0 15.0 22.0 491

LiF–LiCl–LiVO3–Li2SO4 [9] " 21.5 47.2 15.2 16.1 416

LiF–LiCl–LiVO3–Li2MoO4 [17] " 16.5 47.0 28.8 7.6 387

LiF–LiCl–Li2SO4–Li2MoO4 [18, 19] " 16.2 51.5 16.2 16.2 402

LiF–LiVO3–Li2SO4–Li2MoO4 [20] " 25.0 43.8 14.8 16.5 428

Lil–LiVO3–Li2SO4–Li2MoO4 [11] " 48.5 33.5 3.6 41.4 416

* Figures 1, 2, 3, and 4 denote the ordinal numbers of salts in the system.

1626

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 10 2007

GUBANOVA, GARKUSHIN

ternary and quinary crystallization lines meet. From thecomposition of the meeting point, the ratio between the

lithium fluoride and lithium metavanadate concentra-tions in the quinary eutectic was derived (Fig. 4).

491°

610°

449°

485°

575°

591°

581°

575°

575°

858°

485° 575°

Li2SO4 LiVO3620°

533°491°

440°

491°LiCl610°

LiF849°

445°530°

575°

Li2SO4858°

575°

530°

445°

501°610°

B

C Li2MoO4702°

533°

A

ACB

501°

496°436°

463°

573° 575° 573°

497°

449°

485° 575°496°

491°609°

493°

573°591°620°

LiVO3

LiVO3LiF449°533°

491°

497°

530°

575°501°

609°

620°

LiCl

LiClD

D

Li2MoO4Li2SO4Li2MoO4702°

581° 581°702°858°

LiF849°

Fig. 1. Development of the subsystems of the LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system.

445°

402°

436°

445°

c

a

a

B

A

D

b

445°416° 416°

440°449°

387°

436°

C70% LiCl30% Li2SO4

70% LiCl30% LiF

A A70% LiCl

30% LiVO3

70% LiCl30% LiF

70% LiCl30% LiF

70% LiCl30% Li2MoO4

463° 463°

Fig. 2. Phase diagram for isopleth ABCD in the LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system.

LE3 402°

E2 416°

K

E*

E*

b

a c

70% LiClE1 416°

18% Li2SO412% LiF

70% LiCl18% Li2SO412% Li2MoO4

70% LiCl18% Li2SO412% LiVO3

Fig. 3. Phase diagram of isopleth abc in the LiF–LiCL–LiVO3–Li2SO4–Li2MoO4 system.

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 10 2007

LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 SYSTEM 1627

The consecutive studies of sections b– – (Fig. 5),

– (Fig. 6), and LiCl–E*– (Fig. 7) revealed aconstant component ratio (LiF : LiVO3 : Li2MoO4 :Li2SO4) in quinary eutectic E* and the composition ofthe quintuple invariant point (mol %): LiF, 17.4; LiCl,42.0; LiVO3, 17.4; Li2SO4, 11.6; and Li2MoO4, 11.6.

E* E*

E* E* E*

The eutectic phase reaction is L LiF + LiCl +LiVO3 + Li2SO4 + Li2MoO4.

The specific enthalpy of melting for the eutecticcomposition calculated from the results of three mea-surements is 284 kJ/kg.

In summary, we have studied the phase complex ofthe LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system and

500

1.2

E3 402°

E*

2.4 3.6 4.80

T, °C

L

L + LiCl

L + LiCl + Li2SO4

L + LiCl + Li2SO4 + Li2MoO4

LiF + LiCl + LiVO3 + Li2SO4 + Li2MoO4

LiVO3, mol % 4.8% LiVO37.2% Li2MoO418% Li2SO470% LiCl

4.8% LiF7.2% Li2MoO418% Li2SO470% LiCl

L + LiF + LiCl + Li2SO4 + Li2MoO4

K

L + LiCl + LiVO3 + Li2SO4 + Li2MoO4

E2 416°

L

Fig. 4. Phase diagram of isopleth KL in the LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system.

500

7.2

E*

4.8 3.6 2.4b

T, °CL

L + LiCl

L + LiCl + Li2SO4

L + LiCl + Li2SO4 + Li2MoO4

LiF + LiCl + LiVO3 + Li2SO4 + Li2MoO4

Li2MoO4,mol %70% LiCl18% Li2SO412% Li2MoO4

6.0

E*

400

500

16

E*

12 10 818

T, °C L

L + LiCl

L + LiCl + Li2SO4

LiF + LiCl + LiVO3 + Li2SO4 + Li2MoO4

Li2SO4, mol %70% LiCl18% Li2SO4

14

E*

400

6

Fig. 5. Phase diagram of isopleth b– – in theLiF−LiCl–LiVO3–Li2SO4–Li2MoO4 system.

E* E* Fig. 6. Phase diagram of isopleth – in the LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system.

E* E*

1628

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 10 2007

GUBANOVA, GARKUSHIN

experimentally determined the composition, meltingtemperature, and enthalpy of melting for the eutecticalloy in the LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 sys-tem. This alloy can be used as a working medium inheat storages [20].

REFERENCES1. T. V. Gubanova and I. K. Garkushin, Zh. Neorg. Khim.

50 (11), 1892 (2005) [Russ. J. Inorg. Chem. 50 (11),1772 (2005)].

2. V. P. Evgunov, Vvedenie v termicheskii analiz (Samara)[in Russian].

3. N. A. Vasina, E. S. Gryzlova, and S. G. Shaposhnikova,The Thermophysical Properties of Multinary Salt Sys-tems (Khimiya, Moscow, 1984) [in Russian].

4. A. S. Trunin and A. S. Kosmynin, Projective ThermalAnalysis as a Method to Study Heterogeneous Equilibriain Condensed Multinary Systems (Kuibyshev, 1977) [inRussian].

5. The Thermal Constants of Compounds. Handbook,Ed. by V. P. Glushko (VINITI, Mosocw, 1981), Issue10, part 1 [in Russian].

6. Phase Diagrams for Salt Systems, Ed. by V. I. Posy-paiko and E. A. Alekseeva (Metallurgiya, Moscow,1977), Part 3 [in Russian].

7. Melting of Salt Systems. Handbook Ed. by N. K. Vosk-resenskaya (Akad. Nauk SSSR, Moscow, 1961), Vol. 1[in Russian].

8. A. S. Trunin, I. K. Garkushin, A. M. Gasanaliev, andM. A. Dibirov, Izv. Severo-Kavkazsk. Tsentra Vyssh.Shkoly. Estestv. Nauki, No. 3, 53 (1980).

9. Zh. A. Koshkarov, Candidate’s Dissertation in Chemis-try (Inst. of Natural Sciences, Ulan-Ude, 1987).

10. I. N. Belyaev, T. G. Lupeiko, and V. I. Vyalikova,Zh. Neorg. Khim. 20 (9), 2483 (1975).

11. I. K. Garkushin, T. V. Gubanova, A. S. Petrov, andB. V. Anipchenko, Phase Equilibria in Systems of SomeAlkali Metavanadates (Mashinostroenie-1, Moscow) [inRussian].

12. A. I. Sechnoi, I. K. Garkushin, and A. S. Trunin, USSRInventor’s Certificate No. 1274287 (1986).

13. T. V. Gubanova, I. M. Kondratyuk, and I. K. Garkushin,Zh. Neorg. Khim. 50 (12), 2079–2083 (2005) [Russ. J.Inorg. Chem. 50 (12), 1953 (2005)].

14. T. V. Lekomtseva, B. V. Anipchenko, and I. K. Gar-kushin, Zh. Neorg. Khim. 47 (10), 1719 (2002) [Russ. J.Inorg. Chem. 47 (10), 1578 (2002)].

15. B. V. Anipchenko, T. V. Lekomtseva, and I. K. Gar-kushin, Izv. Vyssh. Uchebn. Zaved., Khim. Khim. Tekh-nol. 41 (6), 134 (1998).

16. T. V. Lekomtseva, B. V. Anipchenko, and I. K. Gar-kushin, Zh. Neorg. Khim. 47 (9), 1548 (2002) [Russ. J.Inorg. Chem. 47 (9), 1418 (2002)].

17. T. V. Gubanova, I. M. Kondratyuk, and I. K. Garkushin,Zh. Neorg. Khim. 51 (3), 522 (2006) [Russ. J. Inorg.Chem. 51 (3), 474 (2006)].

18. I. K. Garkushin, T. V. Gubanova, I. M. Kondratyuk, et al.,RF Patent No. 2004134641 (2004).

19. T. V. Gubanova, E. I. Frolov, and I. K. Garkushin,Zh. Neorg. Khim. 52 (2), 308 (2007) [Russ. J. Inorg.Chem. 52 (2), 265 (2007)].

20. I. K. Garkushin, T. V. Gubanova, I. M. Kondratyuk, et al.,RF Patent No. 2004134642, (2004).

500

90

E*

70 60 50100

T, °C

L

L + LiCl

LiF + LiCl + LiVO3 + Li2SO4 + Li2MoO4

LiCl, mol %80

400

40

600

LiCl

E* 363°

Fig. 7. Phase diagram of invariant section LiCl– –E* inthe LiF–LiCl–LiVO3–Li2SO4–Li2MoO4 system.

E*