- Email: [email protected]
Experimental investigation and calculation of the phase diagram of the binary system (NaNO3 + TlNO3)
Accepted Manuscript Experimental investigation and calculation of the phase diagram of the binary system (NaNO3+TlNO3) Abdelkader Abdessattar, Dalila Hellali, David Boa, Hmida Zamali PII:
S0925-8388(15)30788-X
DOI:
10.1016/j.jallcom.2015.08.092
Reference:
JALCOM 35087
To appear in:
Journal of Alloys and Compounds
Received Date: 14 May 2015 Revised Date:
10 August 2015
Accepted Date: 13 August 2015
Please cite this article as: A. Abdessattar, D. Hellali, D. Boa, H. Zamali, Experimental investigation and calculation of the phase diagram of the binary system (NaNO3+TlNO3), Journal of Alloys and Compounds (2015), doi: 10.1016/j.jallcom.2015.08.092. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Experimental investigation and calculation of the phase diagram of the binary system (NaNO3+TlNO3) Abdelkader ABDESSATTARa, Dalila HELLALIa, David BOAb and Hmida ZAMALIa,*.
a
RI PT
Université de Tunis El Manar, Faculté des Sciences, LR 01 SE 10, Laboratoire de Thermodynamique Appliquée, 2092 Tunis, Tunisia. b Laboratoire de Thermodynamique et de Physico-Chimie du Milieu, Université Nangui Abrogoua, UFR SFA, 02 BP 801 Abidjan 02, Côte d’Ivoire. E-mail addresses: [email protected], [email protected], [email protected], [email protected] *Corresponding author: Hmida Zamali. Tel: +21698538106, E-mail: [email protected]
M AN U
SC
Abstract: Solid-solid and solid-liquid equilibria in the binary system (NaNO3+TlNO3) were studied experimentally by simultaneous direct and differential thermal analysis and X-ray diffraction (XRD) techniques. This system exhibits one eutectic reaction at (439 ± 1) K. The phase diagram presents also two polymorphic transitions of TlNO3 at 350 K and 418 K, respectively. The solid-solid phase transition of NaNO3 is obtained at 549 K. Combining our results with experimental data available in the literature, an optimization of the thermodynamic parameters in the binary system (NaNO3+TlNO3) is performed. The calculated phase diagram and thermodynamic functions agree well with experimental data. Keywords: sodium nitrate, thallium nitrate, thermal analysis, XRD, phase diagram, optimization.
1. INTRODUCTION
AC C
EP
TE D
The importance of thermal energy storage has been increasing in the field of energy technology. Alkali and pseudo-alkali nitrates, such as molten salts are potential phase change materials (PCM) [1, 2] for the storage and the transfer of thermal energy. Indeed, these nitrates have better physical and chemical properties than other salts. They are non volatile, do not decompose easily, not very corrosive, they have low melting points and especially they have high transition enthalpies. These nitrates and their mixtures have other interesting applications, such as treatment and development of functional glass [3]. Among these systems, the mixtures (NaNO3+TlNO3) are also suitable candidates for these applications [3]. The knowledge of phase diagram is necessary to predict the thermal behavior and the microstructure evolution. Unfortunately, there is a divergence in literature concerning the (NaNO3+TlNO3) phase diagram [4-6]. The purpose of our study is to investigate experimentally, at atmospheric pressure, the phase limits in this diagram. A thermodynamic assessment of this system is also undertaken in order to describe the phase relationships over the entire composition range with respect to temperature. 2. LITERATURE REVIEW 2.1. Pure nitrates
At atmospheric pressure, both sodium nitrate and thallium nitrate exist in several polymorphic forms above room temperature. Sodium nitrate exhibits, two polymorphic forms α and β having rhombohedral structures. The low temperature form (α) has a calcite-type structure [7, 8], and the high temperature form has an aragonite-type structure [9, 10]. According to K. Xu and Y. Chen [11], this order-disorder transition is of type λ. In fact, α NaNO3 undergoes a gradual transition which ends at a critical temperature. There are two positions disorder model where the NO3 group takes, with equal probability, its original position in the ordered structure and another position rotated by 180° about the trigonal axis from original position [9].
1
ACCEPTED MANUSCRIPT Many crystallographic data of the two polymorphic forms (α and β) of NaNO3 are reported in the literature [12-17]. We gathered in table 1 some crystallographic data with structure and lattice parameters [14-17] Table 1. Crystallographic data of NaNO3
β NaNO3
lattice parameters / Å
trigonal hexagonal Rhombohedral (Calcite) hexagonal Rhombohedral (aragonite)
a = 5.071, c = 16.825 a = 5,060, c = 16,784 a = 6.32, α = 47°14’ a = 5.0696, c = 16.829 a = 6.56 Å α = 45°35’ at 553 K
Reference
RI PT
αNaNO3
Structure
[14] [15] [16] [17] [16]
SC
Allotropic form
Table 2 reports the transition temperature (Tα/β) and the melting one (Tmelting) of sodium nitrate.
Method ATS/DTA ATS/ DTA Adiabatic Calorimetry Adiabatic Calorimetry Drop Calorimetry Adiabatic Calorimetry DSC DSC DSC ATS/DTA Drop Calorimetry DSC Drop Calorimetry DSC Electrochemical measurement Dissolution Calorimetry DSC DTA RAMAN Spect. Dissolution Calorimetry Adiabatic Calorimetry
TE D
Tmelting / K 579 579 579.2 580.2 482.8 583 577.5 579 579 580 578 581 582.5 579 581 583 580 579 581 580 579 584
AC C
EP
Tα/β / K 549 550 547 549.2 549.2 548.5 550 548.5 549 549 535 530 548 549 548 -
M AN U
Table 2. Transition and melting Temperatures of NaNO3
Reference [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40]
The values of transition temperature are according to several authors from 547 K to 550 K [18-27, 31-32, 37], except the transition temperature values 535 K and 530 K, obtained by P. Nguyen-Duy and E. A. Dancy [28] and E. A. Dancy [29] respectively. Regarding the melting temperature, it is measured in the field 577.5 K to 584 K [18, 20-40]. In solid state, thallium nitrate exhibits three polymorphic forms α, β and γ (table 3). 2
ACCEPTED MANUSCRIPT
RI PT
αTlNO3 has, at room temperature, an orthorhombic structure [12, 41-50]. When heated, it undergoes a α/β transformation. M. S. Somayazulu and coll. [45], pointed out that this phase transition is irreversible. According to several authors [42-43, 45, 48], the β form has a rhombohedral structure. But, P. U. M. Sastry and A. Sequeira [41], and R. N. Brown and A. C. McLaren [49] mentioned that the later form, adopted a hexagonal structure; whereas, D. M. Newns and L. A. I. Staveley [12] and B. Cleaver et al. [46] mentioned that this form has a pseudo-hexagonal structure. These different crystallographic results are not contradictory. In fact, the transition from a hexagonal lattice to a rhombohedral cell is possible. In fact, the rhombohedral lattice is obtained by adding two nodes having reduced coordinates (2/3, 1/3, 1/3) and (1/3, 2/3, 2/3) in the primitive hexagonal lattice. From these nodes, we can define the rhombohedral lattice R [51]. The third polymorphic form (γTlNO3) has a cubic structure [12, 41-42, 46-49].
α TlNO3
orthorhombic
β TlNO3
hexagonal rhombohedral rhombohedral rhombohedral hexagonal
Lattice parameters / Å
Reference
a = 6.287, b = 12.31, c = 8.001 a = 12.355(4), b = 8.029(3), c = 6.300(2) at 298 K a = 12.355(6), b = 8.025(4), c = 6.298(3) a = 6.31, b = 12.30, c = 8.01 a = 10.435(1), c = 7.451(1) a = 8.58, α = 89°50 at 353 K a = 4.296(1), α = 89°83(4)’ a = 4.316, α = 89°84’ a = 10.47, c = 7.527 at 403 K a = 4.307(1) a = 8.62 at 443 K a = 4.326(1) at 417 K a = 4.326 at 443 K
[42] [43] [47] [49] [41] [42] [43] [47] [49] [41] [42] [43] [49]
M AN U
structure
TE D
Allotropic form
SC
Table 3. Crystallographic data of TlNO3
γ TlNO3
EP
Temperatures of the different transitions (Tα/β and Tβ/γ) and the melting point (Tmelting) of TlNO3 reported in the literature are gathered in table 4.
AC C
Table 4. Transition and melting Temperatures of TlNO3 Tα/β /K 352 350 352 345 352 349
Tβ/γ / K 416 418 417 418 417.6 417 416
Tmelting / K 479.5 480 478 480 479 483 479
Method Drop Calorimertry Raman Spectrometry DTA DTA DSC DTA DSC -
reference [34] [45] [48] [49] [50] [52] [53] [54] [55]
The majority of the reported values of Tα/β are in the range 345 K to 352 K [45, 48-50, 53, 55]. According to most authors [45, 48-49, 52- 55], the transition β/γ appears between 416 K and 418 K. 3
ACCEPTED MANUSCRIPT
RI PT
The results found by many authors for the melting temperature are consistent with each other and lie in the interval 479 K to 483 K [34, 48-49, 52-55]. The boiling point reported by J. W. Mellor [56] is of 703 K. R. P. Clarck and F. W. Reinhardt [48] have investigated the thermal stability of TlNO3 using TG, DTA in conjunction with gas chromatography and Xray diffraction analysis. The boiling temperature determined by DTA was 740 K. A weight loss was beginning near 653 K with a 50% loss at 793 K. According to these authors, this loss was caused by boiling rather than thermal decomposition. For C. Duval [57] there is no weight change up to 683 K but decomposition above this temperature was observed. 2.2. Binary system (NaNO3+TlNO3)
3. EXPERIMENTAL INVESTIGATION
M AN U
SC
The (NaNO3+TlNO3) phase diagram was studied earlier by C. Van Eyk [4], V. A. Palkin [5], and P. Franzosini and C. Sinistri [6]. The results of C. Van Eyk, showed a eutectic point at 435 K (20.5 mol% NaNO3) and plateaus at 415 K and 352 K corresponding to the two phase transitions of TlNO3 respectively. According to C. Van Eyk [4], there is no miscibility in the solid state. However, V. A. Palkin [5] showed that this phase diagram is characterized by a eutectic point at 435 K, a eutectic plateau extending over the molar composition 0.1 < XNaNO3 < 0.55, and dashed lines indicating the possibility of formation of two solid solutions. P. Franzosini and C. Sinistri [6] studied the liquidus curve and mentioned a eutectic point at 435 K (22.5 mol% NaNO3). In all these investigations, the polymorphic transition in NaNO3 is not mentioned. Moreover, only C. Van Eyk [4] considered, in the (NaNO3+TlNO3) phase diagram, the two polymorphic transitions of TlNO3.
AC C
EP
TE D
In order to establish the phase diagram of (NaNO3+TlNO3) system, we used a simultaneous direct and differential thermal analysis technique (STA/DTA). Detailed description of the STA/DTA apparatus used in the present work has been given in previous works [18, 27]. It consists of an Adamel-Lhomargyam furnace connected to a Setaram PRT 540 C regulator–programmer of temperature, that allows to select a cooling or a heating rate between (0.05 and 10) K/min. The furnace is provided with a metallic block with two symmetrical cavities for platinum crucibles of 3 cm3 capacity. The external diameter of the block was a few millimeters smaller than the furnace, thus limiting the convection current around the test tubes, improving the heat transfer and making the thermal flow propagation homogeneous. Two thin-walled platinum crucibles were used with glove fingers for Chromel–Alumel thermocouples. The latter also act as crucible holders. Electrical and thermal isolations between the sample and the reference were ensured by two quartz tubes surrounding the crucibles. A high sensitive nanovoltmeter 2182A (Keithley) was used to measure the temperature (T) of the sample and the difference of temperature (∆T) between the sample and the reference. The samples were obtained by melting several times appropriate amounts of the pure nitrates: NaNO3 (Aldrich, 99.995 wt% purity) and TlNO3 (Aldrich, 99.90 wt% purity), in a platinum crucible. They were used without further purification but dried for more than 24 hours at 380 K in a desiccator. Care was taken to homogenize the mixtures and to prevent any decomposition. Finally the samples having 2 to 3 g were placed in platinum crucibles and have been analyzed by STA/DTA. The apparatus was calibrated with high pure KNO3 and CsNO3. The transition and melting temperatures, determined with absolute error of 1 K, are respectively 402 K et 610 K for KNO3 and 424 K and 678 K for CsNO3[58]. The heating and cooling rates were sufficiently slow (0.3 to 1 K/min). For the measurements, an average uncertainty of 1 K, for the temperature was observed. 4
ACCEPTED MANUSCRIPT
4. EXPERIMENTAL RESULTS AND DISCUSSION.
M AN U
SC
RI PT
At the solid state, transition temperature of NaNO3 is (549 ± 1) K. His melting point is (579 ± 1) K. These values are in the range of the most of the results published previously [18-29, 31-32, 37] and [18, 20-40], respectively. TlNO3 exhibits two polymorphic phase transitions in the solid state. These transitions appeared at (350 ± 1) K and (418 ± 1) K respectively; the melting point was (481 ± 1) K. Our results are in good agreement with most of the published data [45, 48-50, 53, 55], [45, 48-49, 52- 55] and [34, 48-49, 52-55] respectively. In order to verify its thermal stability, 1 g of TlNO3 was maintained at 696 K during 24 hours, in an isothermal calorimeter type Tian-Calvet. After cooling, this sample was weighed by means of a sensitive balance to a hundredth of milligram. No mass loss was recorded. The phase diagram of the system (NaNO3+TlNO3) was drawn, at atmospheric pressure, using the results of simultaneous simple and differential thermal analysis. The number of peaks observed at heating and at cooling is generally the same. Each sample was analyzed at least four times. The experimental results are listed in table 5. All tabulated temperatures (heating or cooling) are determined by extrapolating the observed temperatures at a heating or cooling rate equal to zero. Table 5. Equilibrium temperatures of the phase diagram (NaNO3+TlNO3) T1/K
0.00 0.07 0.19 0.22 0.29 0.35 0.46 0.56 0.65 0.80 0.85 0.90
349 353 351 351 351 351 351 349 350 350 350 347
EP
AC C 0.95 1.00
T2/K
T3/K
T4/K
T crystallization/K
418 419 419 419 419 419 418 419 417 417 417 417
439 439 439 439 439 439 439 434 437 437 438
548 549
481 465 440 438 457 463 486 502 513 545 556 563
418 -
440 -
549 549
575 579
TE D
X (NaNO3)
-
Our phase diagram is characterized by: - a eutectic point at (439 ± 1) K corresponding to the reaction: liquid = γTlNO3 + αNaNO3. The molar composition of the invariant point, determined by Tammann method, is XNaNO3= 0.20. - a eutectic plateau at (439 ± 1) K extending in the molar composition range 0 < XNaNO3 < 1. - a plateau at (549 ± 1) K corresponding to the polymorphic transition (α → β) of NaNO3. At this temperature, the limit of solubility of NaNO3 in the binary liquid is about 80 mol % NaNO3. - two other plateaus corresponding to the phase transitions of TlNO3 (α → β and β → γ) at (350 ± 1) K and (418 ± 1) K respectively and extending in the whole composition domain 0 ≤ XNaNO3 < 1.
5
ACCEPTED MANUSCRIPT Figure 1 shows X-ray diffraction patterns recorded at room temperature (fig.1) of samples having variable molar fractions of NaNO3 (0 - 0.15 - 0.40 - 0.80 and 1). Only the two pure nitrates TlNO3 and NaNO3 exist in the different mixtures. This result confirms our phase diagram.
SC
5. THERMODYNAMIC MODELING AND OPTIMIZATION
RI PT
Most of the liquidus points found in the present work overlap with those published [4, 5]. We also note that V. A. Palkin [5] did not take into account in his investigation the transition of TlNO3 nor that of NaNO3. The plateaus corresponding to the polymorphic transitions of TlNO3 at (350 ± 1) K and at (418 ± 1) K respectively were already shown only by C. Van Eyk [4] at temperatures (352 K and 415 K). Finally, we can say that our results complete those found by C. Van Eyk [4] but infirm partially those of V. A. Palkin [5].
M AN U
A thermodynamic assessment of the (NaNO3+TlNO3) binary phase diagram is presented in this work for the first time. During the optimization procedure, the present experimental results were combined with the phase diagrams available in the literature [4-6] and the mixing enthalpies at 623 K of binary liquid [59]. The mutual solubilities of NaNO3 and TlNO3 were neglected in agreement with the published phase diagram of C. Van Eyk [4] and our results. The Gibbs energy of pure components, in a given physical state φ, is classically described by the following expression: ,
−
= + + + ∑
(1),
TE D
EP
where a, b, c and dn are coefficients and n represents a set of integers. , is the Gibbs energy of reference. The reference state used in the present work, is the stable pure nitrate at given temperature T. The Gibbs energy functions for pure NaNO3 and TlNO3 are given in Table 6. The reference state generally adopted by the SGTE (Scientist Group of Thermodata Europ) community is the stable element at 298.15 K and 105 Pa, named SER (stable element reference). In this case, the Gibbs energy is referred to the enthalpy of the SER: 298.15#.
AC C
Table 6. Gibbs energy differences Phase ϕ Liquid Rhombo_L (αNaNO3) Rhombo_H (βNaNO3) Cubic (γTlNO3) HCP (βTlNO3) Ortho (αTlNO3)
,
,
−
for pure substances (in J/mol)
NaNO3 [60] 18600 - 32.466 T 0.0 3620 - 6.5938 T -
TlNO3 [This work] 9244.7 - 20.7195 T 3585.1 - 8.963 T 833 - 2 .38 T 0.0
The liquid phase is described by the substitution solution model. This model yields to the following expression for the Gibbs energy: $ − ∑ % = ∑ % & − ' + ( ∑ % % + ,)* (2) where % is the molar fraction of component i in the phase φ. The excess Gibbs energy of mixing ,)* is described by a Redlich-Kister polynomial [61]: 6
ACCEPTED MANUSCRIPT , , ,)* = % %+ ∑,- (3) ,- ,+ % − %+ , i ≠ j = NaNO3 or TlNO3. ,+ are interaction parameters between i and j obtained from optimization. These terms can be temperature dependent as follows: ,,+ = ,.,+ ,/,+ ,0,+ .
RI PT
The optimization was carried out using the Parrot module included in the Thermo-Calc software [62] and the optimized parameters are given in Table 7. Table 7. Thermodynamic parameters in the (NaNO3+TlNO3) system (in J mol-1)
789: 121345 6134 > 789: 121345 6134 A 789: 121345 6134
Reference
= 1049.15 − 2.6022 = − 495.37 − 1.9051 = 2.6021
Present work
M AN U
Liquid
Parameters
SC
Phase
Figure 2 shows the calculated phase diagram together with the experimental data. The calculated phase diagram is in satisfactory agreement with the experimental data. The calculated values for invariant equilibrium are summarized in table 8 and compared with experimental data. As can be seen, a good agreement is obtained.
Reaction
TE D
Table 8. Experimental (exp.) and calculated (calc.) values for the invariant reaction in the binary (NaNO3+TlNO3) system.
Eutectic
Liquid phase composition (XNaNO3) 0.205 0.23 exp. 0.234 calc. 0.225 0.20 exp. 0.20 calc.
T /K
Reference
435 435 437 439 438
[4] [63] [63] [6] This work This work
AC C
EP
Liquid = αNaNO3 (Rhombo_L) + γTlNO3 (Cubic)
Type
The calculated mixing enthalpy of the binary liquid (NaNO3+TlNO3) at 623 K is presented in Figure 3. A very good agreement with the experimental data [59] is observed. 6. Conclusion
The phase diagram of the (NaNO3+TlNO3) system was studied experimentally using a simultaneous simple and differential thermal analysis (STA/DTA) technique. This phase diagram is characterized by a eutectic reaction at (439 ± 1) K. The eutectic composition is 20 mol % NaNO3. Combining our experimental results with those available in the literature, the thermodynamic parameters of the (NaNO3+TlNO3) system have been optimized. These parameters were used to calculate the thermodynamic properties and phase diagram. The calculated mixing enthalpy at 623 K and phase diagram show a satisfactory agreement with the experimental data.
7
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
References [1] T. Bauer, D. Laing, R. Tamme, Characterization of sodium nitrate as Phase Change Material, Int. J. Thermophys. 33 1 (2012) 91-104. [2] T. Bauer, D. Laing, R. Tamme, Overview of PCMs for concentrated solar power in the temperature range 200 to 350 °C, Advances in Science and Technology. 74 (2010) 272-277. [3] Y. Tabei, M. Ueda, T. Ohtsuka, T. Yamashita, Ion - Exchange treatment of glass surface in NaNO3‐TlNO3 molten salt, Electrochemistry. 77 8 (2009) 709-712. [4] C. Van Eyk, Equilibrium in the systems TlNO3-KNO3, TlNO3-AgNO3 and TlNO3-NaNO3, Zeitschrift fur physikalische chemie, stochiometrie und verwandtschaftslehre.; 51 6 (1905) 721-731. [5] V. A. Palkin, Study the melting of the quaternary system of thallium, silver, potassium and sodium nitrates, “Issledovanie plavkosti chetvernoi sistemy iz nitratov talliya, serebra, kaliya I natriya”. Zh Obshch Khim. 19 3 (1949) 411-440. [6] P. Franzosini, C. Sinistri, Proprietà termodinamiche di miscela in sistemi binari di sali fusi., Ric Sci. 33 II-A (1963) 439. [7] S. A. T. Rcdfern, E. Salje, A. Navrotsky, High-temperature enthalpy at the orientational order-disorder transition in calcite: implications for the calcite/aragonite phase equilibrium, Contrib Mineral Petrol. 101 (1989) 479-484. [8] M. T. Dove, B. M. Powell, Neutron Diffraction Study of the Tricritical Orientational Order/Disorder Phase Transition in Calcite at 1260 K, Phys. Chem. Minerals. 16 (1989) 503-507. [9] Y. Shinnaka, Anion rotational disorder in sodium nitrate, J. Phys. Soc. Jpn. 19 8 (1964) 1281-1290. [10] L. A. Siegel, Molecular rotation in sodium cyanide and sodium nitrate, J. Chem. Phys. 17 (1949) 11461150. [11] K. Xu, Y. Chen, Temperature-dependent Raman Spectra of Mixed Crystals of NaNO3-KNO3: Evidence for Limited Solid Solutions, J. Raman. Spectrosc. 30 (1999) 173-179. [12] D. M. Newns, L. A. I. Staveley, The significance of entropies of transition in salts, with special reference to nitrates, Chem. Rev. 66 3 (1966) 267–278. [13] W. W. Schmahl and E. Salje, X-ray diffraction study of the orientational order/disorder transition in NaNO3 : Evidence for order parameter coupling, Phys Chem Minerals 16 (1989) 790-798. [14] P. Cherin, W. C. Hamilton and B. Post ? Position and thermal parameters of oxygen atoms in sodium nitrate, Acta Cryst. (1967). 23, 455-460 . [15] H. Saini and A. Mercier, Dilatation thermique du nitrate de sodium mesurée aux Rayons X, Helv. Phys. Acta 7 (1934) 267–72. [16] F. C. Kracek, E. Posnjak, S. B. Hendricks, Gradual transition in sodium nitrate. II. The structure at various temperatures and ist bearing on molecular rotation, J. Am. Chem. Soc., 53 9 (1931) 3339–3348. [17] C. N. R. Rao and B. Prakash, Natarajan, Crystal structure transformations in inorganic nitrites, nitrates, and carbonates, Volume 53 de NSRDS-NBS, United States. National Bureau of Standards, P 10, 1975. [18] H. Zamali, M. Jemal, Phase Diagrams of Binary Systems: AgNO3-KNO3 and AgNO3-NaNO3, J. Phase Equilib. 16 3 (1995) 235-238. [19] N. Bélaïd-Drira, H. Zamali, M. Jemal, Diagramme de phases du système binaire LiNO3–NaNO3, J. Therm. Anal. 46 (1996) 1449-1458. [20] V. A. Sokolov, N. E. Shmidt, Specific heat and heat of fusion of sodium nitrate, Izv Sektora Fiz –Khim Analiza, Inst Obshch Neorgan Khim Akad Nauk SSSR. 26 (1955) 123-131. [21] A. Mustajoki, Calorimetric studies with regard to the conversion in NaNO3 and the melting process, Kalorimetrische untersuchungen mit Bezug auf die umwandlund in NaNO3 und dessen schmelzvorgang, Ann. Acad. Sci. Fenn. A VI 5 (1957) 1-17. [22] G. J. Janz, F. J. Kelley, J. L. Perano, Melting and pre-melting phenomena in alkali metal nitrates. J. Chem. Eng. Data. 9 1 (1964) 133-136.
8
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
[23] V. C. Reinsborough, F. E. W. Wetmore, Specific heat of sodium nitrate and silver nitrate by medium high temperature adiabatic calorimetry, Aust. J. Chem. 20 (1967) 1-8. [24] R. W. Carling, Heat capacities of NaNO3 and KNO3 from 350 to 800 K, Thermochim. Acta. 60 (1983) 265-275. [25] Y. Takahashi, R. Sakamoto, M. Kamimoto, Heat capacities and latent heats of LiNO3, NaNO3 and KNO3, J. Thermophys. 9 6 (1988) 1081-1090. [26] T. Jriri, J. Rogez, C. Bergman, J. C. Mathieu, Thermodynamic study of the condensed phases of NaNO3, KNO3 and CsNO3 and their transitions, Thermochim. Acta. 266 (1995) 147-161. [27] H. Zamali, Contribution to the thermodynamic study of the binary and ternary mixtures of silver, sodium and potassium nitrate, “Contribution à l’étude thermodynamique des mélanges binaires et ternaires des nitrates d’argent, de potassium et de sodium”. Doctorat d’état es-sciences physiques, D N°194, 196, Univ Tunis II, Tunisie. [28] P. Nguyen-Duy, E. A. Dancy, Calorimetric determination of the thermodynamic properties of the alkali metal salts NaNO3, KNO3, Na2Cr2O7, K2Cr2O7 and their binary eutectic solutions, Thermochim. Acta. 39 (1980) 95-102. [29] E. A. Dancy, Molar enthalpy of the solid – solid transition in NaNO3, Thermochim. Acta. 59 (1982) 251-252. [30] H. M. Goodwin, H. T. Kalmus, On the latent heat of fusion and the specific heat of salts in the solid and liquid state, Phys. Rev. 28 1 (1909) 1-24. [31] F. C. Kracek, Gradual transition in sodium nitrate. I. Physicochemical criteria of the transition, J. Am. Chem. Soc. 53 (1931) 2609–2624. [32] D. J. Rogers, G. J. Janz, Melting-crystallization and premelting properties of NaNO3-KNO3. Enthalpies and heat capacities. J. Chem. Eng. Data. 27 4 (1982) 424-428. [33] M. Bakes, J. Dupuy, J. Guion, Etude d’anomalies électrochimiques d’origine structurale en sels fondues, C. R. Acad. Sci. Paris. 256 11 (1963) 2376-2378. [34] O. J. Kleppa, F. G. McCarty, Heats of fusion of the monovalent nitrates by high–temperature reaction calorimetry, J. Chem. Eng. Data. 8 3 (1963) 331-332. [35] X. Zhang, J. Tian, K. Xu, Y. Gao, Thermodynamic Evaluation of Phase Equilibria in NaNO3-KNO3 System, J. Phase Equilib. 24 5 (2003) 441-446. [36] H. Speros, R. L. Woodhouse, Realization of quantitative differential thermal analysis. I. Heats and rates of solid–liquid transitions, J. Phys. Chem. 67 (1963) 2164-68. [37] C. Vassas-Dubuisson, Effet de la température sur les raies raman de basse fréquence du nitrate de sodium, J. Phys. Radium. 9 3 (1948) 91-92. [38] T. Hu, H. C. Ko, L. G. Hepler, Calorimetric investigations of molten salts, J. Phys. Chem. 68 (1964) 387-390. [39] C. Vallet, Phase diagrams and thermodynamic properties of some molten nitrate mixtures, J. Chem. Thermodynamics. 4 (1972) 105-114. [40] T. Morita, K. Fukuda, H. Kutshuna, Measurements of thermal properties of molten salt mixtures, Kobe Shosen Daigaku kiyo, Dai-2-rui : Shose, Rikogakuhen. 38 (1990) 129-137. [41] P. U. M. Sastry, A. Sequeira, Structure of high-temperature phases of thallous nitrate, Acta Cryst. A52 (1996) C329. [42] S. W. Kennedy, J. H. Patterson, Mechanisms of structure transformations in thallous nitrate crystals, Proc. R. Soc. Lond. A. 283 1395 (1965) 498-508. [43] M. S. Somayazulu, V. K. Wadhawan, Temperature dependence of spontaneous strain in ferroelastic tallous nitrate, J. Appl. Cryst. 22 (1989) 105-109. [44] Y. Takagi, H. Kono, Y. Takeuchi, Brillouin Scattering and domain observation of TlNO3 crystals, Jpn J. Appl. Phys. 44 9B (2005) 7182-7185. [45] M. S. Somayazulu, A. P. Roy, S. K. Deb, Raman spectroscopy studies on the orthorhombic-torhombohedral transition in thallous nitrate, J. Phys. Condens. Matter. 5 (1993) 4557-4562. 9
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
[46] B. Cleaver, E. Rhodes, A. R. Ubbelohde, Studies of phase transformations in nitrates and nitrites. II. Changes in Ultra-Violet absorption spectra accompagning thermal transformations in the crystals, Proc. R. Soc. London Ser A. 276 1367 (1963) 453-460. [47] W. L. Fraser, S. W. Kennedy, M. R. Snow, The nitrate positions in phase III of thallous nitrate, Acta Cryst. B31 (1975) 365-370. [48] R. P. Clark, F. W. Reinhardt, Thermoanalytical investigations of thallous nitrate, J. Therm. Anal. 13 2 (1978) 321-326. [49] R. N. Brown, A. C. McLaren, The thermal transformations in solid thallous nitrate. Acta Cryst. 15 (1962) 977-978. [50] S. Haussühl, Elastic properties of the nitrates of lithium, sodium, potassium, cesium, silver and thallium, Zeitschrift Für Kristallographic. 190 (1990) 111-126. [51] Cristallographie, géométrique et radiocristallographie, (Cours et exercices corrigés). Page 78 Jean-Jacques Rousseau and Alain Gibaud, 3e édition. © Dunod, Paris, 2000, 2007, ISBN 978-2-10-0501984). [52] E. A. Secco, R. A. Secco, Heats of solution/substitution in TlNO3 and RbNO3 crystals from heats of transition. The complete phase diagram of the TlNO3-RbNO3 system, Phys. Chem. Chem. Phys. 1 (1999) 5011-5016. [53] E. Rapoport, C. W. F. T. Pistorius, Polymorphism and melting of ammonium, thallous, and silver nitrates to 45 kbar, J. Chem. Phys. 44 4 (1966) 1514-1519. [54] E. A. Secco, R. A. Secco, Heats of solution/substitution in TlNO3 and CsNO3 crystals and in RbNO3 and CsNO3 crystals from heats of transition: the complete phase diagrams of TlNO3-CsNO3 and RbNO3CsNO3 systems, J. Phys. Chem. solids. 63 (2002) 433-440.
TE D
[55] K. O. Stromme, On the crystal structures of the high-temperature phases of rubidium nitrate, cesium nitrate and tallium nitrate, Acta Chem. Scand. 25 (1971) 211-218. [56] J. W. MELLOR, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. V, John Wiley and Sons, New York, N.Y., 1961, p. 473. [57] C. Duval, Inorganic Thermogravimetric Analysis, Elsevier, New York, N.Y.,1963, p. 613.
AC C
EP
[58] H. Zamali, M. Jemal, Diagrammes de phases des systèmes binaires KNO3–CsNO3 et KNO3–NaNO3, J. Therm. Anal. 41 (1994) 1091-1099. [59] O. J. Kleppa and L. S. Hersh, Calorimetry in liquid thallium nitrate‐alkali nitrate mixtures, J. Chem. Phys. 36 (1962) 544-547. [60] T. Jriri, J. Rogez, J. C. Mathieu and I. Ansara, Thermodynamic analysis of the CsNO3-KNO3-NaNO3 system, J. Phase Equilib. 20 5 (1999) 515-525. [61] O. Redlich and A. Kister, Algebraic Representation of thermodynamic properties and the classification of solutions, Ind. Eng. Chem. 40 (1948) 345-348. [62] B. Sundman, B. Jansson, J. O. Anderson, The Thermo-Calc databank system. Calphad. 9 (1985) 153190. [63] N. K. Voskresenskaya, Handbook of solid-liquid Equilibria in systems of anhydrous inorganic Salts, Isdatel’ stvo Akademii Nauk SSSR, Moskva-Leningrad, vols. I and II 1961.
10
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 1
11
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 2
12
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 3
13
ACCEPTED MANUSCRIPT
FIGURE CAPTION Fig.1. X-ray diffraction patterns recorded at room temperature of samples having different molar compositions (XNaNO3 = 0, 0.15, 0.40, 0.80 and 1).
RI PT
Fig.2. Calculated phase diagram of (NaNO3+TlNO3) system compared with experimental data [The present experimental work, 4, 5]. I: liquid, II: liquid + Cubic, III: liquid + Rhombo_H, IV: liquid + Rhombo_L, V: Cubic + Rhombo_L, VI: HCP+ Rhombo_L, VII: Ortho + Rhombo_L.
AC C
EP
TE D
M AN U
SC
Fig.3. Calculated mixing enthalpy of liquid (NaNO3+TlNO3) at 623 K in comparison with literature data [59].
14
ACCEPTED MANUSCRIPT Highlights ● Alkali and pseudo-alkali nitrates are used as Phase Change Materials. ● TlNO3 is stable in the liquid state up to 200 K more than its melting point. ● We are interested in the phase diagram of the (NaNO3+TlNO3) system. ● (NaNO3 + TlNO3) phase diagram is important sources of information for exploitation in
RI PT
industrial field.
AC C
EP
TE D
M AN U
SC
● (NaNO3+TlNO3) excess Gibbs energy parameters are optimized for the first time.
S0925-8388(15)30788-X
DOI:
10.1016/j.jallcom.2015.08.092
Reference:
JALCOM 35087
To appear in:
Journal of Alloys and Compounds
Received Date: 14 May 2015 Revised Date:
10 August 2015
Accepted Date: 13 August 2015
Please cite this article as: A. Abdessattar, D. Hellali, D. Boa, H. Zamali, Experimental investigation and calculation of the phase diagram of the binary system (NaNO3+TlNO3), Journal of Alloys and Compounds (2015), doi: 10.1016/j.jallcom.2015.08.092. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Experimental investigation and calculation of the phase diagram of the binary system (NaNO3+TlNO3) Abdelkader ABDESSATTARa, Dalila HELLALIa, David BOAb and Hmida ZAMALIa,*.
a
RI PT
Université de Tunis El Manar, Faculté des Sciences, LR 01 SE 10, Laboratoire de Thermodynamique Appliquée, 2092 Tunis, Tunisia. b Laboratoire de Thermodynamique et de Physico-Chimie du Milieu, Université Nangui Abrogoua, UFR SFA, 02 BP 801 Abidjan 02, Côte d’Ivoire. E-mail addresses: [email protected], [email protected], [email protected], [email protected] *Corresponding author: Hmida Zamali. Tel: +21698538106, E-mail: [email protected]
M AN U
SC
Abstract: Solid-solid and solid-liquid equilibria in the binary system (NaNO3+TlNO3) were studied experimentally by simultaneous direct and differential thermal analysis and X-ray diffraction (XRD) techniques. This system exhibits one eutectic reaction at (439 ± 1) K. The phase diagram presents also two polymorphic transitions of TlNO3 at 350 K and 418 K, respectively. The solid-solid phase transition of NaNO3 is obtained at 549 K. Combining our results with experimental data available in the literature, an optimization of the thermodynamic parameters in the binary system (NaNO3+TlNO3) is performed. The calculated phase diagram and thermodynamic functions agree well with experimental data. Keywords: sodium nitrate, thallium nitrate, thermal analysis, XRD, phase diagram, optimization.
1. INTRODUCTION
AC C
EP
TE D
The importance of thermal energy storage has been increasing in the field of energy technology. Alkali and pseudo-alkali nitrates, such as molten salts are potential phase change materials (PCM) [1, 2] for the storage and the transfer of thermal energy. Indeed, these nitrates have better physical and chemical properties than other salts. They are non volatile, do not decompose easily, not very corrosive, they have low melting points and especially they have high transition enthalpies. These nitrates and their mixtures have other interesting applications, such as treatment and development of functional glass [3]. Among these systems, the mixtures (NaNO3+TlNO3) are also suitable candidates for these applications [3]. The knowledge of phase diagram is necessary to predict the thermal behavior and the microstructure evolution. Unfortunately, there is a divergence in literature concerning the (NaNO3+TlNO3) phase diagram [4-6]. The purpose of our study is to investigate experimentally, at atmospheric pressure, the phase limits in this diagram. A thermodynamic assessment of this system is also undertaken in order to describe the phase relationships over the entire composition range with respect to temperature. 2. LITERATURE REVIEW 2.1. Pure nitrates
At atmospheric pressure, both sodium nitrate and thallium nitrate exist in several polymorphic forms above room temperature. Sodium nitrate exhibits, two polymorphic forms α and β having rhombohedral structures. The low temperature form (α) has a calcite-type structure [7, 8], and the high temperature form has an aragonite-type structure [9, 10]. According to K. Xu and Y. Chen [11], this order-disorder transition is of type λ. In fact, α NaNO3 undergoes a gradual transition which ends at a critical temperature. There are two positions disorder model where the NO3 group takes, with equal probability, its original position in the ordered structure and another position rotated by 180° about the trigonal axis from original position [9].
1
ACCEPTED MANUSCRIPT Many crystallographic data of the two polymorphic forms (α and β) of NaNO3 are reported in the literature [12-17]. We gathered in table 1 some crystallographic data with structure and lattice parameters [14-17] Table 1. Crystallographic data of NaNO3
β NaNO3
lattice parameters / Å
trigonal hexagonal Rhombohedral (Calcite) hexagonal Rhombohedral (aragonite)
a = 5.071, c = 16.825 a = 5,060, c = 16,784 a = 6.32, α = 47°14’ a = 5.0696, c = 16.829 a = 6.56 Å α = 45°35’ at 553 K
Reference
RI PT
αNaNO3
Structure
[14] [15] [16] [17] [16]
SC
Allotropic form
Table 2 reports the transition temperature (Tα/β) and the melting one (Tmelting) of sodium nitrate.
Method ATS/DTA ATS/ DTA Adiabatic Calorimetry Adiabatic Calorimetry Drop Calorimetry Adiabatic Calorimetry DSC DSC DSC ATS/DTA Drop Calorimetry DSC Drop Calorimetry DSC Electrochemical measurement Dissolution Calorimetry DSC DTA RAMAN Spect. Dissolution Calorimetry Adiabatic Calorimetry
TE D
Tmelting / K 579 579 579.2 580.2 482.8 583 577.5 579 579 580 578 581 582.5 579 581 583 580 579 581 580 579 584
AC C
EP
Tα/β / K 549 550 547 549.2 549.2 548.5 550 548.5 549 549 535 530 548 549 548 -
M AN U
Table 2. Transition and melting Temperatures of NaNO3
Reference [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40]
The values of transition temperature are according to several authors from 547 K to 550 K [18-27, 31-32, 37], except the transition temperature values 535 K and 530 K, obtained by P. Nguyen-Duy and E. A. Dancy [28] and E. A. Dancy [29] respectively. Regarding the melting temperature, it is measured in the field 577.5 K to 584 K [18, 20-40]. In solid state, thallium nitrate exhibits three polymorphic forms α, β and γ (table 3). 2
ACCEPTED MANUSCRIPT
RI PT
αTlNO3 has, at room temperature, an orthorhombic structure [12, 41-50]. When heated, it undergoes a α/β transformation. M. S. Somayazulu and coll. [45], pointed out that this phase transition is irreversible. According to several authors [42-43, 45, 48], the β form has a rhombohedral structure. But, P. U. M. Sastry and A. Sequeira [41], and R. N. Brown and A. C. McLaren [49] mentioned that the later form, adopted a hexagonal structure; whereas, D. M. Newns and L. A. I. Staveley [12] and B. Cleaver et al. [46] mentioned that this form has a pseudo-hexagonal structure. These different crystallographic results are not contradictory. In fact, the transition from a hexagonal lattice to a rhombohedral cell is possible. In fact, the rhombohedral lattice is obtained by adding two nodes having reduced coordinates (2/3, 1/3, 1/3) and (1/3, 2/3, 2/3) in the primitive hexagonal lattice. From these nodes, we can define the rhombohedral lattice R [51]. The third polymorphic form (γTlNO3) has a cubic structure [12, 41-42, 46-49].
α TlNO3
orthorhombic
β TlNO3
hexagonal rhombohedral rhombohedral rhombohedral hexagonal
Lattice parameters / Å
Reference
a = 6.287, b = 12.31, c = 8.001 a = 12.355(4), b = 8.029(3), c = 6.300(2) at 298 K a = 12.355(6), b = 8.025(4), c = 6.298(3) a = 6.31, b = 12.30, c = 8.01 a = 10.435(1), c = 7.451(1) a = 8.58, α = 89°50 at 353 K a = 4.296(1), α = 89°83(4)’ a = 4.316, α = 89°84’ a = 10.47, c = 7.527 at 403 K a = 4.307(1) a = 8.62 at 443 K a = 4.326(1) at 417 K a = 4.326 at 443 K
[42] [43] [47] [49] [41] [42] [43] [47] [49] [41] [42] [43] [49]
M AN U
structure
TE D
Allotropic form
SC
Table 3. Crystallographic data of TlNO3
γ TlNO3
EP
Temperatures of the different transitions (Tα/β and Tβ/γ) and the melting point (Tmelting) of TlNO3 reported in the literature are gathered in table 4.
AC C
Table 4. Transition and melting Temperatures of TlNO3 Tα/β /K 352 350 352 345 352 349
Tβ/γ / K 416 418 417 418 417.6 417 416
Tmelting / K 479.5 480 478 480 479 483 479
Method Drop Calorimertry Raman Spectrometry DTA DTA DSC DTA DSC -
reference [34] [45] [48] [49] [50] [52] [53] [54] [55]
The majority of the reported values of Tα/β are in the range 345 K to 352 K [45, 48-50, 53, 55]. According to most authors [45, 48-49, 52- 55], the transition β/γ appears between 416 K and 418 K. 3
ACCEPTED MANUSCRIPT
RI PT
The results found by many authors for the melting temperature are consistent with each other and lie in the interval 479 K to 483 K [34, 48-49, 52-55]. The boiling point reported by J. W. Mellor [56] is of 703 K. R. P. Clarck and F. W. Reinhardt [48] have investigated the thermal stability of TlNO3 using TG, DTA in conjunction with gas chromatography and Xray diffraction analysis. The boiling temperature determined by DTA was 740 K. A weight loss was beginning near 653 K with a 50% loss at 793 K. According to these authors, this loss was caused by boiling rather than thermal decomposition. For C. Duval [57] there is no weight change up to 683 K but decomposition above this temperature was observed. 2.2. Binary system (NaNO3+TlNO3)
3. EXPERIMENTAL INVESTIGATION
M AN U
SC
The (NaNO3+TlNO3) phase diagram was studied earlier by C. Van Eyk [4], V. A. Palkin [5], and P. Franzosini and C. Sinistri [6]. The results of C. Van Eyk, showed a eutectic point at 435 K (20.5 mol% NaNO3) and plateaus at 415 K and 352 K corresponding to the two phase transitions of TlNO3 respectively. According to C. Van Eyk [4], there is no miscibility in the solid state. However, V. A. Palkin [5] showed that this phase diagram is characterized by a eutectic point at 435 K, a eutectic plateau extending over the molar composition 0.1 < XNaNO3 < 0.55, and dashed lines indicating the possibility of formation of two solid solutions. P. Franzosini and C. Sinistri [6] studied the liquidus curve and mentioned a eutectic point at 435 K (22.5 mol% NaNO3). In all these investigations, the polymorphic transition in NaNO3 is not mentioned. Moreover, only C. Van Eyk [4] considered, in the (NaNO3+TlNO3) phase diagram, the two polymorphic transitions of TlNO3.
AC C
EP
TE D
In order to establish the phase diagram of (NaNO3+TlNO3) system, we used a simultaneous direct and differential thermal analysis technique (STA/DTA). Detailed description of the STA/DTA apparatus used in the present work has been given in previous works [18, 27]. It consists of an Adamel-Lhomargyam furnace connected to a Setaram PRT 540 C regulator–programmer of temperature, that allows to select a cooling or a heating rate between (0.05 and 10) K/min. The furnace is provided with a metallic block with two symmetrical cavities for platinum crucibles of 3 cm3 capacity. The external diameter of the block was a few millimeters smaller than the furnace, thus limiting the convection current around the test tubes, improving the heat transfer and making the thermal flow propagation homogeneous. Two thin-walled platinum crucibles were used with glove fingers for Chromel–Alumel thermocouples. The latter also act as crucible holders. Electrical and thermal isolations between the sample and the reference were ensured by two quartz tubes surrounding the crucibles. A high sensitive nanovoltmeter 2182A (Keithley) was used to measure the temperature (T) of the sample and the difference of temperature (∆T) between the sample and the reference. The samples were obtained by melting several times appropriate amounts of the pure nitrates: NaNO3 (Aldrich, 99.995 wt% purity) and TlNO3 (Aldrich, 99.90 wt% purity), in a platinum crucible. They were used without further purification but dried for more than 24 hours at 380 K in a desiccator. Care was taken to homogenize the mixtures and to prevent any decomposition. Finally the samples having 2 to 3 g were placed in platinum crucibles and have been analyzed by STA/DTA. The apparatus was calibrated with high pure KNO3 and CsNO3. The transition and melting temperatures, determined with absolute error of 1 K, are respectively 402 K et 610 K for KNO3 and 424 K and 678 K for CsNO3[58]. The heating and cooling rates were sufficiently slow (0.3 to 1 K/min). For the measurements, an average uncertainty of 1 K, for the temperature was observed. 4
ACCEPTED MANUSCRIPT
4. EXPERIMENTAL RESULTS AND DISCUSSION.
M AN U
SC
RI PT
At the solid state, transition temperature of NaNO3 is (549 ± 1) K. His melting point is (579 ± 1) K. These values are in the range of the most of the results published previously [18-29, 31-32, 37] and [18, 20-40], respectively. TlNO3 exhibits two polymorphic phase transitions in the solid state. These transitions appeared at (350 ± 1) K and (418 ± 1) K respectively; the melting point was (481 ± 1) K. Our results are in good agreement with most of the published data [45, 48-50, 53, 55], [45, 48-49, 52- 55] and [34, 48-49, 52-55] respectively. In order to verify its thermal stability, 1 g of TlNO3 was maintained at 696 K during 24 hours, in an isothermal calorimeter type Tian-Calvet. After cooling, this sample was weighed by means of a sensitive balance to a hundredth of milligram. No mass loss was recorded. The phase diagram of the system (NaNO3+TlNO3) was drawn, at atmospheric pressure, using the results of simultaneous simple and differential thermal analysis. The number of peaks observed at heating and at cooling is generally the same. Each sample was analyzed at least four times. The experimental results are listed in table 5. All tabulated temperatures (heating or cooling) are determined by extrapolating the observed temperatures at a heating or cooling rate equal to zero. Table 5. Equilibrium temperatures of the phase diagram (NaNO3+TlNO3) T1/K
0.00 0.07 0.19 0.22 0.29 0.35 0.46 0.56 0.65 0.80 0.85 0.90
349 353 351 351 351 351 351 349 350 350 350 347
EP
AC C 0.95 1.00
T2/K
T3/K
T4/K
T crystallization/K
418 419 419 419 419 419 418 419 417 417 417 417
439 439 439 439 439 439 439 434 437 437 438
548 549
481 465 440 438 457 463 486 502 513 545 556 563
418 -
440 -
549 549
575 579
TE D
X (NaNO3)
-
Our phase diagram is characterized by: - a eutectic point at (439 ± 1) K corresponding to the reaction: liquid = γTlNO3 + αNaNO3. The molar composition of the invariant point, determined by Tammann method, is XNaNO3= 0.20. - a eutectic plateau at (439 ± 1) K extending in the molar composition range 0 < XNaNO3 < 1. - a plateau at (549 ± 1) K corresponding to the polymorphic transition (α → β) of NaNO3. At this temperature, the limit of solubility of NaNO3 in the binary liquid is about 80 mol % NaNO3. - two other plateaus corresponding to the phase transitions of TlNO3 (α → β and β → γ) at (350 ± 1) K and (418 ± 1) K respectively and extending in the whole composition domain 0 ≤ XNaNO3 < 1.
5
ACCEPTED MANUSCRIPT Figure 1 shows X-ray diffraction patterns recorded at room temperature (fig.1) of samples having variable molar fractions of NaNO3 (0 - 0.15 - 0.40 - 0.80 and 1). Only the two pure nitrates TlNO3 and NaNO3 exist in the different mixtures. This result confirms our phase diagram.
SC
5. THERMODYNAMIC MODELING AND OPTIMIZATION
RI PT
Most of the liquidus points found in the present work overlap with those published [4, 5]. We also note that V. A. Palkin [5] did not take into account in his investigation the transition of TlNO3 nor that of NaNO3. The plateaus corresponding to the polymorphic transitions of TlNO3 at (350 ± 1) K and at (418 ± 1) K respectively were already shown only by C. Van Eyk [4] at temperatures (352 K and 415 K). Finally, we can say that our results complete those found by C. Van Eyk [4] but infirm partially those of V. A. Palkin [5].
M AN U
A thermodynamic assessment of the (NaNO3+TlNO3) binary phase diagram is presented in this work for the first time. During the optimization procedure, the present experimental results were combined with the phase diagrams available in the literature [4-6] and the mixing enthalpies at 623 K of binary liquid [59]. The mutual solubilities of NaNO3 and TlNO3 were neglected in agreement with the published phase diagram of C. Van Eyk [4] and our results. The Gibbs energy of pure components, in a given physical state φ, is classically described by the following expression: ,
−
= + + + ∑
(1),
TE D
EP
where a, b, c and dn are coefficients and n represents a set of integers. , is the Gibbs energy of reference. The reference state used in the present work, is the stable pure nitrate at given temperature T. The Gibbs energy functions for pure NaNO3 and TlNO3 are given in Table 6. The reference state generally adopted by the SGTE (Scientist Group of Thermodata Europ) community is the stable element at 298.15 K and 105 Pa, named SER (stable element reference). In this case, the Gibbs energy is referred to the enthalpy of the SER: 298.15#.
AC C
Table 6. Gibbs energy differences Phase ϕ Liquid Rhombo_L (αNaNO3) Rhombo_H (βNaNO3) Cubic (γTlNO3) HCP (βTlNO3) Ortho (αTlNO3)
,
,
−
for pure substances (in J/mol)
NaNO3 [60] 18600 - 32.466 T 0.0 3620 - 6.5938 T -
TlNO3 [This work] 9244.7 - 20.7195 T 3585.1 - 8.963 T 833 - 2 .38 T 0.0
The liquid phase is described by the substitution solution model. This model yields to the following expression for the Gibbs energy: $ − ∑ % = ∑ % & − ' + ( ∑ % % + ,)* (2) where % is the molar fraction of component i in the phase φ. The excess Gibbs energy of mixing ,)* is described by a Redlich-Kister polynomial [61]: 6
ACCEPTED MANUSCRIPT , , ,)* = % %+ ∑,- (3) ,- ,+ % − %+ , i ≠ j = NaNO3 or TlNO3. ,+ are interaction parameters between i and j obtained from optimization. These terms can be temperature dependent as follows: ,,+ = ,.,+ ,/,+ ,0,+ .
RI PT
The optimization was carried out using the Parrot module included in the Thermo-Calc software [62] and the optimized parameters are given in Table 7. Table 7. Thermodynamic parameters in the (NaNO3+TlNO3) system (in J mol-1)
789: 121345 6134 > 789: 121345 6134 A 789: 121345 6134
Reference
= 1049.15 − 2.6022 = − 495.37 − 1.9051 = 2.6021
Present work
M AN U
Liquid
Parameters
SC
Phase
Figure 2 shows the calculated phase diagram together with the experimental data. The calculated phase diagram is in satisfactory agreement with the experimental data. The calculated values for invariant equilibrium are summarized in table 8 and compared with experimental data. As can be seen, a good agreement is obtained.
Reaction
TE D
Table 8. Experimental (exp.) and calculated (calc.) values for the invariant reaction in the binary (NaNO3+TlNO3) system.
Eutectic
Liquid phase composition (XNaNO3) 0.205 0.23 exp. 0.234 calc. 0.225 0.20 exp. 0.20 calc.
T /K
Reference
435 435 437 439 438
[4] [63] [63] [6] This work This work
AC C
EP
Liquid = αNaNO3 (Rhombo_L) + γTlNO3 (Cubic)
Type
The calculated mixing enthalpy of the binary liquid (NaNO3+TlNO3) at 623 K is presented in Figure 3. A very good agreement with the experimental data [59] is observed. 6. Conclusion
The phase diagram of the (NaNO3+TlNO3) system was studied experimentally using a simultaneous simple and differential thermal analysis (STA/DTA) technique. This phase diagram is characterized by a eutectic reaction at (439 ± 1) K. The eutectic composition is 20 mol % NaNO3. Combining our experimental results with those available in the literature, the thermodynamic parameters of the (NaNO3+TlNO3) system have been optimized. These parameters were used to calculate the thermodynamic properties and phase diagram. The calculated mixing enthalpy at 623 K and phase diagram show a satisfactory agreement with the experimental data.
7
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
References [1] T. Bauer, D. Laing, R. Tamme, Characterization of sodium nitrate as Phase Change Material, Int. J. Thermophys. 33 1 (2012) 91-104. [2] T. Bauer, D. Laing, R. Tamme, Overview of PCMs for concentrated solar power in the temperature range 200 to 350 °C, Advances in Science and Technology. 74 (2010) 272-277. [3] Y. Tabei, M. Ueda, T. Ohtsuka, T. Yamashita, Ion - Exchange treatment of glass surface in NaNO3‐TlNO3 molten salt, Electrochemistry. 77 8 (2009) 709-712. [4] C. Van Eyk, Equilibrium in the systems TlNO3-KNO3, TlNO3-AgNO3 and TlNO3-NaNO3, Zeitschrift fur physikalische chemie, stochiometrie und verwandtschaftslehre.; 51 6 (1905) 721-731. [5] V. A. Palkin, Study the melting of the quaternary system of thallium, silver, potassium and sodium nitrates, “Issledovanie plavkosti chetvernoi sistemy iz nitratov talliya, serebra, kaliya I natriya”. Zh Obshch Khim. 19 3 (1949) 411-440. [6] P. Franzosini, C. Sinistri, Proprietà termodinamiche di miscela in sistemi binari di sali fusi., Ric Sci. 33 II-A (1963) 439. [7] S. A. T. Rcdfern, E. Salje, A. Navrotsky, High-temperature enthalpy at the orientational order-disorder transition in calcite: implications for the calcite/aragonite phase equilibrium, Contrib Mineral Petrol. 101 (1989) 479-484. [8] M. T. Dove, B. M. Powell, Neutron Diffraction Study of the Tricritical Orientational Order/Disorder Phase Transition in Calcite at 1260 K, Phys. Chem. Minerals. 16 (1989) 503-507. [9] Y. Shinnaka, Anion rotational disorder in sodium nitrate, J. Phys. Soc. Jpn. 19 8 (1964) 1281-1290. [10] L. A. Siegel, Molecular rotation in sodium cyanide and sodium nitrate, J. Chem. Phys. 17 (1949) 11461150. [11] K. Xu, Y. Chen, Temperature-dependent Raman Spectra of Mixed Crystals of NaNO3-KNO3: Evidence for Limited Solid Solutions, J. Raman. Spectrosc. 30 (1999) 173-179. [12] D. M. Newns, L. A. I. Staveley, The significance of entropies of transition in salts, with special reference to nitrates, Chem. Rev. 66 3 (1966) 267–278. [13] W. W. Schmahl and E. Salje, X-ray diffraction study of the orientational order/disorder transition in NaNO3 : Evidence for order parameter coupling, Phys Chem Minerals 16 (1989) 790-798. [14] P. Cherin, W. C. Hamilton and B. Post ? Position and thermal parameters of oxygen atoms in sodium nitrate, Acta Cryst. (1967). 23, 455-460 . [15] H. Saini and A. Mercier, Dilatation thermique du nitrate de sodium mesurée aux Rayons X, Helv. Phys. Acta 7 (1934) 267–72. [16] F. C. Kracek, E. Posnjak, S. B. Hendricks, Gradual transition in sodium nitrate. II. The structure at various temperatures and ist bearing on molecular rotation, J. Am. Chem. Soc., 53 9 (1931) 3339–3348. [17] C. N. R. Rao and B. Prakash, Natarajan, Crystal structure transformations in inorganic nitrites, nitrates, and carbonates, Volume 53 de NSRDS-NBS, United States. National Bureau of Standards, P 10, 1975. [18] H. Zamali, M. Jemal, Phase Diagrams of Binary Systems: AgNO3-KNO3 and AgNO3-NaNO3, J. Phase Equilib. 16 3 (1995) 235-238. [19] N. Bélaïd-Drira, H. Zamali, M. Jemal, Diagramme de phases du système binaire LiNO3–NaNO3, J. Therm. Anal. 46 (1996) 1449-1458. [20] V. A. Sokolov, N. E. Shmidt, Specific heat and heat of fusion of sodium nitrate, Izv Sektora Fiz –Khim Analiza, Inst Obshch Neorgan Khim Akad Nauk SSSR. 26 (1955) 123-131. [21] A. Mustajoki, Calorimetric studies with regard to the conversion in NaNO3 and the melting process, Kalorimetrische untersuchungen mit Bezug auf die umwandlund in NaNO3 und dessen schmelzvorgang, Ann. Acad. Sci. Fenn. A VI 5 (1957) 1-17. [22] G. J. Janz, F. J. Kelley, J. L. Perano, Melting and pre-melting phenomena in alkali metal nitrates. J. Chem. Eng. Data. 9 1 (1964) 133-136.
8
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
[23] V. C. Reinsborough, F. E. W. Wetmore, Specific heat of sodium nitrate and silver nitrate by medium high temperature adiabatic calorimetry, Aust. J. Chem. 20 (1967) 1-8. [24] R. W. Carling, Heat capacities of NaNO3 and KNO3 from 350 to 800 K, Thermochim. Acta. 60 (1983) 265-275. [25] Y. Takahashi, R. Sakamoto, M. Kamimoto, Heat capacities and latent heats of LiNO3, NaNO3 and KNO3, J. Thermophys. 9 6 (1988) 1081-1090. [26] T. Jriri, J. Rogez, C. Bergman, J. C. Mathieu, Thermodynamic study of the condensed phases of NaNO3, KNO3 and CsNO3 and their transitions, Thermochim. Acta. 266 (1995) 147-161. [27] H. Zamali, Contribution to the thermodynamic study of the binary and ternary mixtures of silver, sodium and potassium nitrate, “Contribution à l’étude thermodynamique des mélanges binaires et ternaires des nitrates d’argent, de potassium et de sodium”. Doctorat d’état es-sciences physiques, D N°194, 196, Univ Tunis II, Tunisie. [28] P. Nguyen-Duy, E. A. Dancy, Calorimetric determination of the thermodynamic properties of the alkali metal salts NaNO3, KNO3, Na2Cr2O7, K2Cr2O7 and their binary eutectic solutions, Thermochim. Acta. 39 (1980) 95-102. [29] E. A. Dancy, Molar enthalpy of the solid – solid transition in NaNO3, Thermochim. Acta. 59 (1982) 251-252. [30] H. M. Goodwin, H. T. Kalmus, On the latent heat of fusion and the specific heat of salts in the solid and liquid state, Phys. Rev. 28 1 (1909) 1-24. [31] F. C. Kracek, Gradual transition in sodium nitrate. I. Physicochemical criteria of the transition, J. Am. Chem. Soc. 53 (1931) 2609–2624. [32] D. J. Rogers, G. J. Janz, Melting-crystallization and premelting properties of NaNO3-KNO3. Enthalpies and heat capacities. J. Chem. Eng. Data. 27 4 (1982) 424-428. [33] M. Bakes, J. Dupuy, J. Guion, Etude d’anomalies électrochimiques d’origine structurale en sels fondues, C. R. Acad. Sci. Paris. 256 11 (1963) 2376-2378. [34] O. J. Kleppa, F. G. McCarty, Heats of fusion of the monovalent nitrates by high–temperature reaction calorimetry, J. Chem. Eng. Data. 8 3 (1963) 331-332. [35] X. Zhang, J. Tian, K. Xu, Y. Gao, Thermodynamic Evaluation of Phase Equilibria in NaNO3-KNO3 System, J. Phase Equilib. 24 5 (2003) 441-446. [36] H. Speros, R. L. Woodhouse, Realization of quantitative differential thermal analysis. I. Heats and rates of solid–liquid transitions, J. Phys. Chem. 67 (1963) 2164-68. [37] C. Vassas-Dubuisson, Effet de la température sur les raies raman de basse fréquence du nitrate de sodium, J. Phys. Radium. 9 3 (1948) 91-92. [38] T. Hu, H. C. Ko, L. G. Hepler, Calorimetric investigations of molten salts, J. Phys. Chem. 68 (1964) 387-390. [39] C. Vallet, Phase diagrams and thermodynamic properties of some molten nitrate mixtures, J. Chem. Thermodynamics. 4 (1972) 105-114. [40] T. Morita, K. Fukuda, H. Kutshuna, Measurements of thermal properties of molten salt mixtures, Kobe Shosen Daigaku kiyo, Dai-2-rui : Shose, Rikogakuhen. 38 (1990) 129-137. [41] P. U. M. Sastry, A. Sequeira, Structure of high-temperature phases of thallous nitrate, Acta Cryst. A52 (1996) C329. [42] S. W. Kennedy, J. H. Patterson, Mechanisms of structure transformations in thallous nitrate crystals, Proc. R. Soc. Lond. A. 283 1395 (1965) 498-508. [43] M. S. Somayazulu, V. K. Wadhawan, Temperature dependence of spontaneous strain in ferroelastic tallous nitrate, J. Appl. Cryst. 22 (1989) 105-109. [44] Y. Takagi, H. Kono, Y. Takeuchi, Brillouin Scattering and domain observation of TlNO3 crystals, Jpn J. Appl. Phys. 44 9B (2005) 7182-7185. [45] M. S. Somayazulu, A. P. Roy, S. K. Deb, Raman spectroscopy studies on the orthorhombic-torhombohedral transition in thallous nitrate, J. Phys. Condens. Matter. 5 (1993) 4557-4562. 9
ACCEPTED MANUSCRIPT
M AN U
SC
RI PT
[46] B. Cleaver, E. Rhodes, A. R. Ubbelohde, Studies of phase transformations in nitrates and nitrites. II. Changes in Ultra-Violet absorption spectra accompagning thermal transformations in the crystals, Proc. R. Soc. London Ser A. 276 1367 (1963) 453-460. [47] W. L. Fraser, S. W. Kennedy, M. R. Snow, The nitrate positions in phase III of thallous nitrate, Acta Cryst. B31 (1975) 365-370. [48] R. P. Clark, F. W. Reinhardt, Thermoanalytical investigations of thallous nitrate, J. Therm. Anal. 13 2 (1978) 321-326. [49] R. N. Brown, A. C. McLaren, The thermal transformations in solid thallous nitrate. Acta Cryst. 15 (1962) 977-978. [50] S. Haussühl, Elastic properties of the nitrates of lithium, sodium, potassium, cesium, silver and thallium, Zeitschrift Für Kristallographic. 190 (1990) 111-126. [51] Cristallographie, géométrique et radiocristallographie, (Cours et exercices corrigés). Page 78 Jean-Jacques Rousseau and Alain Gibaud, 3e édition. © Dunod, Paris, 2000, 2007, ISBN 978-2-10-0501984). [52] E. A. Secco, R. A. Secco, Heats of solution/substitution in TlNO3 and RbNO3 crystals from heats of transition. The complete phase diagram of the TlNO3-RbNO3 system, Phys. Chem. Chem. Phys. 1 (1999) 5011-5016. [53] E. Rapoport, C. W. F. T. Pistorius, Polymorphism and melting of ammonium, thallous, and silver nitrates to 45 kbar, J. Chem. Phys. 44 4 (1966) 1514-1519. [54] E. A. Secco, R. A. Secco, Heats of solution/substitution in TlNO3 and CsNO3 crystals and in RbNO3 and CsNO3 crystals from heats of transition: the complete phase diagrams of TlNO3-CsNO3 and RbNO3CsNO3 systems, J. Phys. Chem. solids. 63 (2002) 433-440.
TE D
[55] K. O. Stromme, On the crystal structures of the high-temperature phases of rubidium nitrate, cesium nitrate and tallium nitrate, Acta Chem. Scand. 25 (1971) 211-218. [56] J. W. MELLOR, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. V, John Wiley and Sons, New York, N.Y., 1961, p. 473. [57] C. Duval, Inorganic Thermogravimetric Analysis, Elsevier, New York, N.Y.,1963, p. 613.
AC C
EP
[58] H. Zamali, M. Jemal, Diagrammes de phases des systèmes binaires KNO3–CsNO3 et KNO3–NaNO3, J. Therm. Anal. 41 (1994) 1091-1099. [59] O. J. Kleppa and L. S. Hersh, Calorimetry in liquid thallium nitrate‐alkali nitrate mixtures, J. Chem. Phys. 36 (1962) 544-547. [60] T. Jriri, J. Rogez, J. C. Mathieu and I. Ansara, Thermodynamic analysis of the CsNO3-KNO3-NaNO3 system, J. Phase Equilib. 20 5 (1999) 515-525. [61] O. Redlich and A. Kister, Algebraic Representation of thermodynamic properties and the classification of solutions, Ind. Eng. Chem. 40 (1948) 345-348. [62] B. Sundman, B. Jansson, J. O. Anderson, The Thermo-Calc databank system. Calphad. 9 (1985) 153190. [63] N. K. Voskresenskaya, Handbook of solid-liquid Equilibria in systems of anhydrous inorganic Salts, Isdatel’ stvo Akademii Nauk SSSR, Moskva-Leningrad, vols. I and II 1961.
10
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 1
11
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 2
12
ACCEPTED MANUSCRIPT
AC C
EP
TE D
M AN U
SC
RI PT
FIGURE 3
13
ACCEPTED MANUSCRIPT
FIGURE CAPTION Fig.1. X-ray diffraction patterns recorded at room temperature of samples having different molar compositions (XNaNO3 = 0, 0.15, 0.40, 0.80 and 1).
RI PT
Fig.2. Calculated phase diagram of (NaNO3+TlNO3) system compared with experimental data [The present experimental work, 4, 5]. I: liquid, II: liquid + Cubic, III: liquid + Rhombo_H, IV: liquid + Rhombo_L, V: Cubic + Rhombo_L, VI: HCP+ Rhombo_L, VII: Ortho + Rhombo_L.
AC C
EP
TE D
M AN U
SC
Fig.3. Calculated mixing enthalpy of liquid (NaNO3+TlNO3) at 623 K in comparison with literature data [59].
14
ACCEPTED MANUSCRIPT Highlights ● Alkali and pseudo-alkali nitrates are used as Phase Change Materials. ● TlNO3 is stable in the liquid state up to 200 K more than its melting point. ● We are interested in the phase diagram of the (NaNO3+TlNO3) system. ● (NaNO3 + TlNO3) phase diagram is important sources of information for exploitation in
RI PT
industrial field.
AC C
EP
TE D
M AN U
SC
● (NaNO3+TlNO3) excess Gibbs energy parameters are optimized for the first time.