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AZERBAIJAN CHEMICAL JOURNAL № 3 2019
ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
UDC 544.344.3:546.28924 ROENTGENOGRAPHIC INVESTIGATION OF SOLID-PHASE EQUILIBRIA IN THE
TlSbTe2-TlTbTe2 SYSTEM
G.I.Alakbarzade
National Aerospace Agency of Azerbaijan Republic alakbarzadegi@gmail.com Received 29.04.2019
The solid-phase equilibria in the TlSbTe2-TlTbTe2 system been forts studied by using the powder X-ray diffraction method. It was established that despite the isostructural character of the starting compounds (hexagonal structure, Sp. Gr. R-3m), the system is characterized by a limited mutual solubility of the components. The solubility based on TlSbTe2 reaches ~30 mol%, and base on TlTbTe2 is about 10 mol%. The lattice parameters of solid solutions are calculated based on powder roentgenograms.
Keywords: TlSbTe2-TlTbTe2 system, solid solutions, powder X-ray diffraction, crystal lattice.
https://doi.org/10.32737/0005-2531-2019-3-84-87
Introduction
Complex chalcogenides of heavy metals, including thallium, have attracted great interest for decades as functional materials which possess thermoelectric, optical, photoelectric and other properties [1-9]. Recent studies have shown that they are of interest as topological insulators [9-13] and Weyl semimetals [14]. Some of them have photoconductivity and are promising for use as y- and X-ray detectors [15, 16].
Optimization of the functional properties of the above-mentioned materials can be achieved by directed changing of their composition. This, in turn, requires the study of systems consisting of structural analogs, since they can be expected to form wide areas of solid solutions [17-19].
In this paper, we present the results of X-ray diffraction studies of solid-phase equilibria in the TlSbTe2-TlTbTe2 system.
Earlier, we investigated some similar systems, in which new phases of variable composition were revealed: Tl9BiTe6-Tl9ErTe6 [20], Tl2Te-Sb2Te3-Bi2Te3 [21], 3ThS+Sb2Tes^ 3ThTe+Sb2S [22], 3Tl2Se+Sb2Te3^3ThTe+Sb2Se3 [23].
TlSbTe2 compound melts with decomposition in a peritectic reaction at 753 K [24] and crystallizes in a hexagonal structure (Sp. Gr.R-3m) with parameters a = 4.425, c = 23.303Â, z = 3 [25].
TlTbTe2 compound is structural analogue of TlSbTe2 and has following lattice parameters: a = 4.416, c = 24.27 Â, z = 3 [26].
The thermodynamic properties of the TlSbTe2 compound were studied in the [27].
Experiments and results
Initial compounds TlSbTe2 and TlTbTe2 were synthesized by direct melting of high purity elements (at least 99.999 at.%). All elements were purchased from Alpha Aesar. The synthesis of TlSbTe2 was carried out in evacuated (~10- Pa) quartz ampoule at 1000 K, followed thermal annealing at 700 K for 200 h. To synthesize TlTbTe2, the ampoule was heated slowly to 1000 K in a furnace, allowed to remain at 1000 K for 100 h, and then slowly cooled down to room temperature. In order to complete the reaction, the intermediate ingot of TlTbTe2 was crushed in a dry box, pressed into pellets and then, the heating procedure was repeated at 900 K for 500 h.
The purity of the synthesized compounds was controlled by the X-ray diffraction analysis by using the Bruker D8 diffractometer (CuKa radiation), between 10°<29<70° at room temperature. The unit cell constant of initial compounds and intermediate alloys were calculated by indexing of powder patterns using Topas V3.0 software (Table). Calculated lattice parameters of TlSbTe2 and TlTbTe2 were close to literature data [24, 25].
Alloys of the TlSbTe2-TlTbTe2 system were prepared by melting the initial compounds in evacuated (~10-2Pa) quartz ampoules with subsequent thermal annealing at 700 K for 600 h.
The powder X-ray diffraction patterns of some annealed alloys are presented on Figure 1. As can be seen, the diffraction patterns of alloys
ROENTGENOGRAPHS INVESTIGATION OF SOLID-PHASE EQUILIBRIA
85
containing 70 and 90 mol% TlSbTe2 are qualitatively similar to those for pure TlSbTe2. X-ray diffraction patterns of alloys with compositions of 20, 50 and 70 mol% TlSbTe2 consist of a set of diffraction lines of both phases.
The concentration dependences of the lattices parameters (Table, Figure 2) were constructed in order to determine the mutual solubility of the initial compounds. These dependencies have fracture points at compositions of
~10 and ~70 mol% TlSbTe2, which correspond to the limiting compositions of a- and P-solid solutions based on TlTbTe2 and TlSbTe2, respectively. It should be noted that in the a +85 P two-phase region, the lattice periods of the two coexisting phases have constant values regardless of the overall composition of the alloys, while within the homogeneity region of the P-phase the lattice parameters are a linear function of the composition, i.e. obey the Vegard's law.
2Theta (Coupled TwoTheta/Theta) WL=1.54060
Fig. 1. The powder X-ray diffraction patterns of some annealed alloys of the TlSbTe2-TlTbTe2 system.
Phase compositions and crystallographic parameters of phases of the TlSbTe2-TlTbTe2
Compositions % TlSbTe2 Phase compositions Rhombic lattice parameters, Â
0 (TlTbTe2) a a = 4.4245(4); c = 23.3025(20)
10 a a = 4.42375 (4); c = 23.3751(21)
20 a+P a-phase: a = 4.42374 (4), c = 23.3759(21) P-phase: a = 4.4180(5), c = 24.0061(20)
40 a+P a-phase: a = 4.42376 (5), c = 23.3747(21) P-phase: a = 4.4183(4), c = 24.0024(20)
60 a+P a-phase: a = 4.42375 (5), c = 23.3753(21) P-phase: a = 4.4184(5), c = 24.0052(20)
70 P a = 4.4180(5), c = 23.9991(20)
80 P a = 4.4173(4), c = 24.1754(20)
90 P a = 4.4165(5), c = 24.2516(21)
100 P a = 4.4155(5), c = 24.2682(21)
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G.I.ALAKBARZADE
Fig. 2. The concentration dependences of the lattices parameters of some annealed alloys of the TlSbTe2-TlTbTe2 system.
structured metal chalcogenides:
Conclusion
Based on the XRD results, the formation of a wide area of solid solutions is the of on TlSbTe2 (70 mol%) is established in the TlSbTe2-TlTbTe2 system. The solubility based on TlTbTe2 is much lower and does not exceed 10 mol%. The crystal lattices parameters of the obtained solid solutions are determined. The solid solutions obtained are of practical interest as potential topological insulators.
Acknowledgments
The work has been carried out within the framework of the international joint research laboratory "Advanced Materials for Spintronics and Quantum Computing" (AMSQC) established between Institute of Catalysis and Inorganic Chemistry of ANAS (Azerbaijan) and Donostia International Physics Center (Basque Country, Spain).
References
1. Applications of Chalcogenides: S, Se, and Te, ed. by G.K.Ahluwalia. Springer, 2016. 445 p.
2. Babanly M.B., Yusibov Y.A., Abishev V.T. Ternary Chalcogenide Based on Copper and Silver. BSU Publisher, 1993. 341 p.
3. Alonso-Vante N. Chalcogenide Materials for Energy Conversion: Pathways to Oxygen and Hydrogen Reactions. Publisher Springer International Publishing. 2018. 226 p.
4. Gao M-R., Xu Y-F., Jiang J. and Yu S-H. Nano-
synthesis,
modification, and applications in energy conversion and storage devices. Chem. Soc. Reviews. 2013. V. 42. P. 2986-3017.
5. Kanatzidis M.G. Advances in thermoelectrics: From single phases to hierarchical nanostructures and back. MRS Bull. 2015. V. 40 (8). P. 687-694.
6. Deger D., Uluta§ K., Yakut §., Kara H. Dielectric properties and ac conductivity of TlSbTe2 thin films. Mater. Sci. in Semiconductor Processing. 2015. V. 38. P. 1-7.
7. Shi Y., Assoud A., Ponou S., Lidin S., Kleinke H. A new material with a composite crystal structure causing ultralow thermal conductivity and outstanding thermoelectric properties: Tl2Ag12Te7+s. J. Am. Chem. Soc. 2018. V. 140. № 27. P. 8578-8581.
8. Kurosaki K., Yamanaka S. Low-thermal conductivity group 13 chalcogenides as high-efficiency thermoelectric materials. Phys. Status Solidi A. 2013. V. 210. № 1. P. 82-86.
9. Shi J., Cerqueira T.F.T., Cui W., Nogueira F., Botti S., Marques M.A.L. High-throughput search of ternary chalcogenides for p-type transparent electrodes. Scientific Reports. 2017. № 7. P. 43179.
10. Banik A., Roychowdhury S. and Biswas K. The journey of tin chalcogenides towards highperformance thermoelectrics and topological materials. Chem. Commun. 2018. V. 54. P. 65736590
11. Eremeev S. V., Koroteev Y. M., Chulkov E.V. Ternary thallium-based semimetal chalcogenides Tl-V-VI2 as a new class of three-dimensional topological insulators // JETP Lett. 2010. V. 91. P. 594-598.
12. Pielmeier F., Landolt G., Slomski B., Mu S.,
ROENTGENOGRAPHIC INVESTIGATION OF SOLID-PHASE EQUILIBRIA
B7
Berwanger J., Eich A., Khajetoorians A.,Wiebe J., Aliev Z.S., Wiesendanger R., Osterwalder J., Chulkov E.V., Giessibl F.J., Hugo Dil, Babanly M.B. Response of the topological surface state to surface disorder in TlBiSe2 // New J. Phys. 2015. V. 17. P. 023067-8
13. Singh B., Lin H., Prasad R., Bansil A. Role of surface termination in realizing well-isolated topological surface states within the bulk band gap in TlBiSe2 and TlBiTe2. Phys. Rev B. 2016. V. 93. P. 085113-1-085113-8.
14. Ruan J., Jian S.K., Zhang D., Yao H., Zhang H., Zhang S-C., Xing D. Ideal Weyl semimetals in the chalcopyrites CuTlSe2, AgTlTe2, AuTlTe2, and ZnPbAs2. Phys Rev Lett. 2016. V. 115. P. 226801-1- 226801-5.
15. Johnsen S., Liu Z.F., Peters J.A. Thallium chal-cohalides for X-ray and y-ray detection. J. Am. Chem. Soc. 2011. V. 133. P. 10030-10033.
16. Das S., Peters J.A., Lin W.W. Charge transport and observation of persistent photoconductivity in Tl6SeI4 single crystals. J. Phys. Chem. Lett. 2017. V. 8(7). P. 1538-1544.
17. Babanly M.B., Chulkov E.V., Aliev Z.S., Shevel'kov A.V., and Amiraslanov I. R. Phase diagrams in the materials science of topological insulators based on metal chalcogenides. Russ. J. Inorg. Chem. 2017. V. 62. № 13. P. 1703-1729.
18. Andreev O.V., Bamburov V.G., Monina L.N. Phase equilibria in the sulfide systems of the 3d, 4/-elements. Ekaterinburg: Editorial Publication Department of the UR RAS. 2015. 213 P.
19. Imamaliyeva S.Z., Babanly D.M., Tagiev D.B., Babanly M.B. Physicochemical Aspects of
Development of Multicomponent Chalcogenide Phases Having the Tl5Te3 Structure: A Review. Russ. J. Inorg. Chem. 2018. V. 63. № 13. P. 1703-1724.
20. Mekhdiyeva I.F., Babanly K.N., Mahmudova87 M.A., S.Z.Imamaliyeva.The Tl9ErTe6-Tl9BiTe6 system and some properties of solid solutions. Azerb.Chem. J. 2018. № 2. P. 80-86.
21. Veysova S.M., Guseinov Z.A., Guseinov F.N., Babanly M.B. Phase equilibria and thermodynamic properties of the Tl2Te-Sb2Te3-Bi2Te3 system. NEWS of BSU. Ser. sciences. 2004. № 3. P. 10-20.
22. JafarovY.I., Babanly M.B., Amiraslanov I.R. et al. Study of the 3Tl2S+Sb2Te3+3Tl2Te+Sb2S3 reciprocal system. J.Alloys Compd. 2014. V. 582. P. 659-669.
23. Jafarov Y.I., Shevelkov A.V., Babanly M.B., Aliev Z.S. Experimental investigation of the 3Tl2Se+Sb2Te3^3Tl2Te+Sb2Se3 phase diagram. J.Alloy Compd. 2013. V. 555. P. 184-192.
24. Babanly M.B., Akhmad'yar A, Kuliev A.A. System Tl-Sb-Te. Russ. J. Inorg. Chem. 1985. V. 30. P. 1051-1059.
25. Hockings E.F., White J.G. The crystal structures of TlSbTe2 and TlBiTe2. Acta Crystallographica. 1961. V. 14. P. 328.
26. Duczmal M. Structure, wlasciwosci magnetzcyne i pole krzstalicyne w potrojnzch chalkogenkach lantonowcow i talu TlLnX2 (X=S, Se lub Te). Po-litechniki Un-t Wroclawskiej. Wroclaw. 2003. 67 p.
27. Babanly M.B., Ahmad'yar A., Kuliev A.A. Thermodynamic Properties of Intermediate Phases in Tl-Sb(Bi)-Te Systems. Russ.J. Phys. Chem. 1985. V. 59. № 3. P. 676-678.
TlSbTe2-TlTbTe2 SISTEMINDO BORKFAZA TARAZLIQLARIN RENTGENOQRAFIJK TODQIQI
G.i.0l3kbarzad3
ilk dafa olaraq TlSbTe2-TlTbTe2 sisteminda barkfaza tarazliqlan rentgenfaza analizi usulu ila tadqiq olunmu§dur. Muayyan edilmi§dir ki, ilkin birla§malar eyni kristallik qurulu§a (heksaqonal F.q. R-3m) malik olsa da, sistemda ilkin komponentlarin mahdud qar§iliqli hall olurlar. TlSbTe2 asasinda hallolma ~70 mol.%, TlTbTe2 asasinda isa 10 mol% ta§kil edir. Ovuntu rentgenoqramlari asasinda bark mahlullann qafas parametrlari hesablanmi§dir.
Agar sozlar: TlSbTe2-TlTbTe2sistemi, bark mahlullar, rentgenfaza analizi, kristal qafas.
РЕНТГЕНОГРАФИЧЕСКОЕ ИССЛЕДОВАНИЕ ТВЕРДОФАЗНЫХ РАВНОВЕСИЙ В СИСТЕМЕ
TlSbTe2-TlTbTe2
Г.И.Алекберзаде
Впервые методом рентгенфазового анализа изучены твердофазные равновесия в системе TlSbTe2-TlTbTe2. Установлено, что несмотря на изоструктурность исходных соединений (гексагональная структура, пр.гр R-3m), данная система характеризуется ограниченной взаимной растворимостью компонентов. Растворимость на основе TlSbTe2 составляет ~70 мол%, а на основе TlTbTe2 - 10 мол.%. На основании порошковых дифрактограмм рассчитаны параметры кристаллической решетки твердых растворов.
Ключевые слова: система TlSbTe2-TlTbTe2, твердые растворы, порошковая рентгенография, кристаллическая решетка.
