792

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 5, pp. 792–796. © Pleiades Publishing, Inc., 2009.Original Russian Text © T.V. Gubanova, E.I. Frolov, I.K. Garkushin, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 5, pp. 851–856.

The title ternary systems have been investigated inorder to search compositions promising for the use aselectrolytes for chemical current sources and for thedescription of phase equilibria.

METHODS AND REAGENTS

The title ternary systems were investigated by dif-ferential thermal analysis (DTA). We used an F-116photoamplifier for amplifying the signal of a differen-tial thermocouple and a KSP-4 potentiometer for thedetection of DTA curves. The cooling and heating rateswere 15 K/min. As the thermopower sensor, we usedPt/Pt–Rh thermocouples, and as the reference sub-stance, we used freshly calcined Al

2

O

3

. Cooling rateswere 12–15 K/min. The system was investigated in thetemperature range from 350 to

900°ë

. The concentra-tions of all elements are expressed in molar percent,and the temperatures of phase transitions are expressedin degrees centigrade. The sample weight was 0.3 g.

The starting high-purity grade Li

2

SO

4

, chemicallypure grade LiBr, and pure for analysis grade LiF werepreliminary calcined or fused (LiBr). Lithium metavan-adate was synthesized by us according as described in[1]. The reagent purity was verified by X-ray powderdiffraction (a DRON-3.0 installation, Cu

K

α

radiation,Ni

β

-filter).

EXPERIMENTAL

Design of experiments in LiF

–

LiBr

–

LiVO

3

andLiBr

–

Li

2

SO

4

–

LiVO

3

ternary systems was performedaccording to the rules of the projection thermographicmethod [2]. The data on phase transformations of indi-vidual substances were taken from [3]. The binary sub-systems of the ternary systems were investigated previ-

ously by various authors (Table 1). The LiF–LiBr, LiF

–

LiVO

3

,

LiBr

–

LiVO

3

,

and LiBr

–

Li

2

SO

4

systems wereinvestigated previously. Our data on the compositionsand melting points at invariant points coincide with theresults in [4–7]. In the LiVO

3

–

Li

2

SO

4

system, only aeutectic point was found in [8]. We also noticed a solid-phase transformation in Li

2

SO

4

(

α

/

β

)

below the solidusline at

575°ë

. In the course of verification, we foundthat the melting point and composition of the eutecticdiffer from those in [8].

Our refined compositions and melting points ofthe alloys corresponding to invariant points in thebinary subsystems are presented in Table 1 and plot-ted in system’s models, that is, concentration trian-gles (Figs. 1, 4).

For the investigation in the LiF–LiBr

–

LiVO

3

system,we selected and investigated rational polytherm

AB

(

A

= 20% LiF + 80% LiBr;

B

= 20.0%

LiVO

3

+ 80%LiBr; Figs. 1, 2) in the crystallization field of lithiumbromide.

The intersection of secondary and tertiary crystalli-zation branches determines the projection of the ternary

eutectic point on the plane of the

AB

section and theratio of concentrations of the LiF and LiVO

3

compo-nents in the ternary eutectic. By the investigation of the

invariant join LiBr

E

(Fig. 3), we deter-mined the composition and melting point of the ternaryeutectic in the system under investigation (Table 1).

The phase fields corresponding to the starting com-ponents, namely, lithium fluoride, lithium bromide, andlithium metavanadate, were demarcated.

The specific enthalpy of melting of the eutectic alloydetermined by comparison with the specific enthalpy of

E

E

LiF

–

LiBr

–

LiVO

3

and LiBr

–

Li

2

SO

4

–

LiVO

3

Ternary Systems

T. V. Gubanova, E. I. Frolov, and I. K. Garkushin

State Comprehensive Institution of Higher Professional Education Samara State Technical University, ul. Galaktionovskaya 141, Samara, 443010 Russia

Received February 4, 2008

Abstract

—Phase equilibria in the LiF

–

LiBr

–

LiVO

3

and LiBr

–

Li

2

SO

4

–

LiVO

3

systems have been investigatedby differential thermal analysis. Eutectic compositions have been revealed (mol %). In the LiF

–

LiBr

–

LiVO

3

system, 16.8% LiF, 52.0% LiBr, 31.2% LiVO

3

with a melting point of

428°

C

;

in the LiBr

–

Li

2

SO

4

–

LiVO

3

sys-tem, 52.0% LiBr, 38.0% LiVO

3

, 10.0% Li

2

SO

4

with a melting point of

444°

C. Crystallization fields of thephases have been demarcated.

DOI:

10.1134/S0036023609050180

PHYSICOCHEMICAL ANALYSIS OF INORGANIC SYSTEMS

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY

Vol. 54

No. 5

2009

LiF–LiBr–LiVO

3

AND LiBr–Li

2

SO

4

–LiVO

3

TERNARY SYSTEMS 793

Table 1.

Characteristics of eutectic and peritectic compositions in binary and ternary systems

System Point character

Percentages of components, mol %Melting point,

°

CLiF LiBr LiVO

3

Li

2

SO

4

LiF–LiBr Eutectic 23.0 77.0 467

LiF–LiVO

3

"

23.0 77.0 573

LiBr–LiVO

3

"

57.0 43.0 473

LiBr–Li

2

SO

4

Eutectic 75.0 25.0 480

Peritectic 30.5 69.5 575

LiVO

3

–Li

2

SO

4

Eutectic 87.0 13.0 591

LiF–LiBr–LiVO

3

Eutectic 16.8 52.0 31.2 428

LiBr–LiVO

3

–Li

2

SO

4

Eutectic 52.0 38.0 10.0 444

Peritectic 5.5 82.5 12.0 575

LiBr550

°

A

E

BE

LiF

LiVO

3

e

2

573

°

428

°

LiVO

3

LiF849

°

620

°

e

3

467

°

e

1

473

°

Fig. 1. Concentration triangle of the LiF–LiBr–LiVO3 system.

794

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 5 2009

GUBANOVA et al.

500

0 5 10 15 20

400

A

LiBr

E

LiBr + LiVO3

LiF + LiBr + LiVO3

LiBr + LiF

Composition, mol % LiVO320% LiF 80% LiBr

20% LiVO380% LiBr

T, °C

B

Fig. 2. Phase diagram of the AB polytherm of the LiF–LiBr–LiVO3 system.

550

500

100 90 80 70 60 50

400

LiBr

E 428°

LiBrE

LiF + LiBr + LiVO3

Composition, mol % LiBr

T, °C

Fig. 3. Phase diagram of the LiBr– invariant join of theLiF–LiBr–LiVO3 system.

E–E

a reference (Na2MoO4, polymorphic transition at451°ë, 113.8 kJ/kg) after [8] and the results of threemeasurements was 226 kJ/kg.

In the LiBr–Li2SO4–LiVO3 ternary system, the CDpolytherm was selected and investigated (C = 55%LiVO3 + 45% Li2SO4; D = 55% LiBr + 45% Li2SO4;Figs. 4, 5) in the crystallization field of lithium sulfate.

The investigation of the polytherm CD allowed us todetermine the projection of the ternary eutectic onthe plane of the CD section and the ratio of concentra-tions of the LiBr and LiVO3 components in the ternaryeutectic Ö.

By the investigation of the invariant join Li2SO4

E (Fig. 6), which connects the Li2SO4 vertex

E

E

LiBr550°

E

E

D

LiVO3

e2591°

444°

LiVO3Li2SO4858° 620°

e3480°

e1473°

LiBr

α-Li2SO4

β-Li2SO4

1p 575°

P575°

C

Fig. 4. Concentration triangle of the LiBr–Li2SO4–LiVO3 system.

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 5 2009

LiF–LiBr–LiVO3 AND LiBr–Li2SO4–LiVO3 TERNARY SYSTEMS 795

800

600

0 10 20 30 40 50400C

α-Li2SO4

β-Li2SO4

E

LiBr + β-Li2SO4

LiBr + LiVO3 + β-Li2SO4

LiVO3 + β-Li2SO4

Composition, mol % LiBr55% LiVO345% Li2SO4

55% LiBr45% Li2SO4

T, °C

D

Fig. 5. Phase diagram of the CD polytherm of the LiBr–Li2SO4–LiVO3 system.

800

600

100 90 80 70 60 50

400

α-Li2SO4

β-Li2SO4

E

LiBr + LiVO3 + β-Li2SO4

Composition, mol % Li2SO4

Li2SO4 40 30 20 10

700

500

α β-Li2SO4

E 444°

T, °C

Fig. 6. Phase diagram of the Li2SO4– invariant join of the LiBr–Li2SO4–LiVO3 system.E–E

796

RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 54 No. 5 2009

GUBANOVA et al.

with the projection of the ternary eutectic we deter-mined the composition and melting point of the ternaryeutectic (Table 1). The phase fields were demarcated;the crystallization field of Li2SO4 is presented by twophases (α- and β-Li2SO4). Using the graphic method,we determined the composition of the ternary transitionpoint that corresponds to the α β-Li2SO4 polymor-phic transformation (Tables 2, 3). The composition ofthe ternary peritectic (α/β-Li2SO4) is determined graph-ically.

The specific enthalpy of the eutectic composition,which was determined by comparison with the specificenthalpy of melting of a reference (Na2MoO4, polymor-phic transformation at 451°ë, 113.8 kJ/kg) after [8] andresults of three measurements, was 253 kJ/kg.

In this work, we investigated the phase complexes ofthe LiF–LiBr–LiVO3 and LiBr–Li2SO4–LiVO3 ternarysystems and experimentally determined the composi-tions and melting points of the alloys corresponding toternary eutectics in the LiF–LiBr–LiVO3 and LiBr–Li2SO4–LiVO3 systems.

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

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

2. A. S. Trunin and A. S. Kosmynin, Projective ThermalAnalysis as a Method of Investigation of HeterogeneousEquilibria in Condensed Multinary Systems (Kuibyshev,1977) [in Russian].

3. Thermal Constants. Handbook, Ed. by V. P. Glushko(VINITI, Moscow, 1981), Vol. X, Part 1 [in Russian].

4. G. E. Egortsev, I. K. Garkushin, and I. M. Kondratyuk,Proceedings of the 6th International Conference “Fun-damental Problems of Electrochemical Power Produc-tion” (Saratov, 2005), p. 51 [in Russian].

5. Zh. A. Koshkarov, V. I. Lutsyk, M. V. Mokhosoev, et al.,Zh. Neorg. Khim. 32 (6), 1480 (1987).

6. Liquid–Solid Phase Diagrams of Salt Systems, Ed. byV. I. Posypaiko and E. A. Alekseeva (Metallurgiya, Mos-cow, 1977), Part III [in Russian].

7. The Melting of Salt Systems. Handbook, Ed. byN. K. Voskresenskaya (Akad. Nauk SSSR, Mos-cow/Leningrad, 1961), Vol. 1 [in Russian].

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

9. N. A. Vasina, E. S. Gryzlova, and S. G. Shaposhnikova,The Thermophysical Properties of Multinary Systems(Khimiya, Moscow, 1984) [in Russian].

Table 2. Phase reactions in the LiF–LiBr–LiVO3 ternarysystem

Element of the phase diagram (Fig. 1) Phase reaction

e1E L LiBr + LiVO3

e2E L LiF + LiVO3

e3E L LiF + LiBr

E L LiF + LiBr + LiVO3

Table 3. Phase reactions in the LiBr–Li2SO4–LiVO3 ternarysystem

Element of the phase diagram (Fig. 4) Phase reaction

e1E L LiBr + LiVO3

e2P L LiVO3 + α-Li2SO4

pP L + α-Li2SO4 β-Li2SO4

PE L LiVO3 + β-Li2SO4

e3E L β-Li2SO4 + LiBr

E L LiBr + β-Li2SO4 + Li2MoO4

P L + α-Li2SO4 β-Li2SO4 + LiVO3