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CHEMICAL PROBLEMS 2021 no. 3 (19) ISSN 2221-8688
135
UDC 546.05
STUDY OF THE CONDITIONS FOR THE ACQUISITION OF TbAsS4 IN ETHYLENE
GLYCOL
H.A. Imanov, G.M. Huseynov
Institute of Natural Resources of the Nakhchivan Branch of National Academy of Sciences of Azerbaijan, H.
Aliyev str. 35, city of Nakhchivan, AZ 7000, Azerbaijan Tel:+994708716976, e-mail: huseyn.imanov1991 @gmail.com
Received 27.08.2021 Accepted 04.10.2021
Abstract: The article presents the results of obtaining thallium thioarsenate in ethylene glycol medium and physicochemical analysis methods (XRD, DTG, TG and SEM). It was found that when ethylene glycol is used as a solvent and TlNO3 and As2S5 as the initial component, thallium thioarsenate is obtained at 353 K temperature. Thallium thioarsenate is formed by the interaction of TlNO3 and As2Ss at a ratio of 4:15 mol. After the compound was obtained at a temperature of 353 K (pH = 7-8), thermally processed at a temperature of523-543 K, the melting point of the thallium thioarsenate sample has been 683 K. According to the results of thermogravimetric analysis, at temperatures above 733 K thallium thioarsenate decomposes in nitrogen gas environment. The micromorphology of the ThAsS4 compound obtained in the ethylene glycol medium was studied and it was determined that nanoparticles of the Tl3AsS4 compound are formed at a temperature of 353 K.
Keywords: thermogravimetric analysis, ethylene glycol, melting point, micromorphology, thallium
thioarsenate, nanoparticles
DOI: 10.32737/2221-8688-2021-3-135-142
Introduction
The compounds formed by thallium with arsenic and glass-like alloys obtained on their basis are valuable functional materials with semiconducting, photoelectric, acousto-optical etc. properties.
The chemical compound, TbAsS4, has first been obtained as a precipitate by Hawley through adding sodium polysulfide to an aqueous solution containing five-valent arsenic salts. However, the compound obtained by this method had a very small degree of crystallization. It is known that the optical and optoacoustic properties of Tl3AsS4 have not been studied in detail before [1]. Orange-red orthorhombic crystals of Tl3AsS4 were synthesized by the hydrothermal method. In some Tl-sulfides, as well as in natural and synthetic Tl - thiosalts, Tl-Tl and Tl-S distances and coordination numbers (cn) have been determined [2]. In addition, another study has provided information on obtaining, physical-chemical analysis and microstructures of
Tl3AsS4 nanoparticles under hydrothermal conditions [3].
As is known, crystals of triple chalcogenides, as well as TI3AsS4, are used as elements of acousto-optical filters operating in the infrared region of the spectrum [4]. Despite the unique acousto-optical properties in the infrared range of the spectrum, single crystals of ternary thallium chalcogenides Tl3AsSe3, Tl3AsS4, Tl3PSe4, Tl3VS4, TlGaSe2, TlGaS2, TlInSe2, TbTaS4 and TbTaS4 have not been sufficiently studied. The TbAsS4 combination has high optical transmission, low acoustic losses at high frequencies, and good chemical and mechanical properties. For this reason, the authors pointed out that it can be used in acousto-optical devices [4-7].
Phase equilibrium and glass formation in the Tl-As-S system, as well as the physical and chemical properties of the intermediate phases have been studied in several studies [8-9,10]. The compounds and alloys in the system are mainly obtained through direct synthesis.
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CHEMICAL PROBLEMS 2021 no. 3 (19)
It is clear from the above literature that very little is known about the acquisition and study of the properties of TbAsS4 in the solutions of organic compounds. Taking this
into consideration, we aimed to investigate the interaction between TlNO3 and As2S5 in an ethylene glycol medium and obtain the TbAsS4 compound individually.
Experimental part
With allowance for methods first mentioned in the literature [11], by the following reaction the As2S5 sample was obtained by releasing H2S gas in 2 hours from a
solution of 0.5 g of sodium arsenate containing 0.18 g of arsenic in ethylene glycol, acidified with 10 N hydrochloric acids.
2Na3AsO4+5H2S+6HCWAs2S5+6NaCl+8H2O (1)
To obtain the thallium thioarsenate compound, 0.33 g of As2S5 and 1.06 g of TlNO3 (As2S5 / TlNO3 = 4 : 15 mol ratio) were mixed by adding 50 ml of ethylene glycol. Using 0.1 M ammonium hydroxide, the pH of the medium was kept in the range of 7-8 and the reaction mixture was mixed (Glassco 710.AG.01 magnetic heater&stirrer (350 °C/1600 RPM)
with a magnetic stirrer for 3 hours, at the end of the process the precipitate was filtered, first washed with distilled water and then with ethanol. Chemically pure ethylene glycol was added to the sediment and stored in a microwave oven (KD WBFY-201) at 353 K for 78 hours. The equation of the reaction can be summarized as follows:
4As2S5+15TlNO3+12C2H6O2^5Tl3AsS4+3H3AsO4+15HCl+12C2H4O (2)
At the end of the process, the precipitate (~10-1 Pa) at a temperature of 363 K. was re-filtered, washed and dried in a vacuum
Results and discussion
Chemical analysis. The study of the conditions for the production of Tl3AsS4 was carried out based on the results of a number of experimental experiments. A sample of a certain amount of TbAsS4 was dissolved in nitric acid and the solution was completely evaporated. The dry residue was dissolved in distilled water and made up to 100 ml. The amount of arsenic in the solution was determined by colorimetric method (KFK - 2 - UHL 4.2) [14]. For this purpose, several samples were taken from the solution, ammonium molybdate and hydrazine solution was added to them and boiled in a water bath for 10 minutes. In this case, the optical densities of arsenomolybdate blue complexes formed in solutions were measured and the amount of arsenic was determined in the degree curve. In addition, the amount of arsenic in the filtrate was determined by the same method. The amount of thallium was
determined in a separate sample according to the known methodology [12]. The results of chemical analysis, the mass of the sediment, the amount of As+5 ions passed to the solution show that the composition of the sample corresponds to the formula Tl3AsS4. The results of the determination of the mass of the compound obtained and the amount of As+5 ions passed to the solution are given in Table 1.
It was found that when was pH=7-8 and T>373 K, (ThS)x(As2S3)1-x (x = 0.1 - 0.9) -containing sediments were obtained from mixtures of primary components (As2S5 and TlNO3) in other mole ratios in the solution. It is known that when the temperature is T > 363 K, As2S5 decomposes by the reaction As2S5 ^ As2S3 + 2S. When the temperature is T < 363 K, TbAsS4 is obtained from the amount taken in the appropriate ratio (4 : 15 mol) corresponding to reaction (2).
Table 1. Determination of the mass of thallium thioarsenate obtained and the amount of As+5 ions
passed to the solution.
As2S5, g TlNOs, g Tl3AsS4 sediment, g The amount of As+5 ion transferred to the solution, g
Experimental Theoretical Experimental Theoretical
0.3300 1.0634 1.0318 1.0862 0.0507 0.0598
0.4397 1.4169 1.3864 1.4473 0.0689 0.0797
0.4928 1.5880 1.5230 1.6221 0.0786 0.0894
0.3862 1.2445 1.1369 1.2712 0.0592 0.0700
0.3643 1.1739 1.1038 1.1991 0.0541 0.0661
0.5705 1.8384 1.7257 1.8778 0.0907 0.1035
0.3027 0.9754 0.8869 0.9963 0.0413 0.0549
0.4631 1.4923 1.5096 1.5243 0.0762 0.0840
The results of chemical analysis of the and sulfur) are given in Table 2. composition of the compound (thallium, arsenic
Table 2. Chemical analysis of TbAsS4
Amount of elements,%
<D Tl As S
as <+H o ■s s O om A Theoretical Experimental Theoretical Experimental Theoretical Experimental
0.815 0.612 0.602 0.075 0.071 0.128 0.123
Figure 1. Diffractogram of thallium thioarsenate in ethylene glycol medium at 353 K
Based on the results of chemical analysis of the sample, it was determined that the composition of the compound corresponds to thallium thioarsenate.
XRD Analysis. X-ray phase analysis (D2 PHASER "Bruker", CuK<x, 20, 20-80 degrees) of the sediment obtained in an ethylene glycol medium at 353 K temperature showed that the main ingredient is tallium tioarsenate (TbAsS4). It contains a small amount (0.02%) of a mixture of free sulfur (Ss). This is clearly indicated by the intensity maxima in the diffractogram (Figure 1).
The thallium thioarsenate sample was thermally processed at 523-543 K (-10"2 Pa vacuum) for 2 hours and its composition was checked by X-ray analysis (2D PHASER "Brooker", CuK<x, 20, 20-80 degrees). It was found that the sediment consists of the Tl3AsS4 compound and has an orthorhombic structure (Space gr.: Pnma; lattice. par.: a = 0.9268 nm, b = 0.9339 nm, c = 1.1128 nm, a = ( = y = 90°). The results of the sample analysis are consistent with the PDF (01-077-1539) value and confirm its individuality (Figure 2).
Figure 2. Diffractogram of thermally processed TbAsS4 compound at 543
SEM imaging. The micromorphology of the TbAsS4 compound obtained in an ethylene glycol medium at 353 K temperature was studied under a HITACHI TM3000 microscope. As can be seen from the SEM figure in the 5 and 10 micrometer area of the compound, the
sediment from the solution is composed of aggregates of nanoparticles (Fig. 3). It is clear from the SEM images that it was not possible to determine the size of the thallium thioarsenate nanoparticles because they were shapeless.
Fig. 3. SEM image of the TI3ASS4 compound.
Elemental analysis. In order to determine the stoichiometric composition of the TbAsS4 compound, elemental analysis of the composition of the obtained compound was carried out; energy-dispersion spectrum and electronic images were taken (Fig. 4,5), (Launch Trion XL dilution refrigerator - OXFORD
device)). Based on the results, the mass and atomic ratios of thallium, arsenic and sulfur in the compounds were determined. Proceeding from the results of elemental analysis, it was established that the simple formula of the compound obtained in ethylene glycol medium is Tl3AsS4.
Element Mass,% Atom%
S 14.89 48.50
As 9.05 12.62
Tl 76.07 38.88
Cam 100.00
0 2 4 6 S 10 12 14
Полная шкала SE-413 имп. Курсор: 0.0QC кгЕ
Fig. 4. Element composition and energy-dispersion spectrum of TbAsS4 compound
Fig. 5. Electronic images of TbAsS4
TG/DTG/DTA analysis. TG, DTA and
DTG analysis (NETZSCH STA 449F3) of thallium thioarsenate obtained in ethylene glycol medium at 353 K was performed (Figure 6). As can be seen from the thermogram, at a temperature of 573 K, adsorbed substances (gases, ethylene glycol) are released in the Tl3AsS4 compound. At this temperature, the total mass loss is 0.28%. Melting of thallium thioarsenate occurs at relatively low
temperatures 683 K). Due to the sulfur content of the sediment, this can be clearly seen from the deep endothermic effects on the DTA curve. At a temperature of 733-773 K, sulfur is released from the compound. In this case, the mass loss is 11.24%. Arsenic sublimates as a result of the decomposition of thallium thioarsenate in the temperature range 733-938 K. In this case, the mass loss is 26.19%, which corresponds to the total mass of arsenic and
sulfur in the compound. At a temperature of temperature rises. The results of chemical and 948-983 K, thallium azide is formed, after X-ray analysis showed that the main component which the sample decomposes as the of the residue is free thallium metal.
Figure 6. TG, DTG, DTA curves of thallium thiorsenate compound
Conclusion
TI3ASS4 compound was obtained at 353 K temperature on the basis of AS2S5 and TINO3 components in ethylene glycol medium. It was determined that this compound was obtained at a ratio of 4:15 moles of the initial components and a pH range of 7-8. The individuality of the Tl3AsS4 sample obtained in ethylene glycol medium and at a temperature of 353 K was confirmed by X-ray analysis after heat treatment at a temperature of 523 - 543 K. The elemental composition of the compound was specified and
the energy-dispersion spectrum was plotted. The micromorphology of the Tl3AsS4 compound was studied and it was not possible to determine the size of the thallium thioarsenate nanoparticles because they were formless. TG, DTG and DTA analyses of the compound were carried out, the characteristics of physico-chemical processes occurring in the N2 environment in the range of 293 - 1223 K temperature was clarified.
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ETiLENQLiKOL MUHiTIiNDd Tl3AsS4 BiRLd^MdSiNiN ALINMASININ TdDQiQi
Н.Э. imanov, Q.M. Huseynov
AMEA Naxgivan Bolmdsi Tdbii Ehtiyatlar institutu, AZ 7000, Heyddr dliyev kug. 35.
Tel: +994708716976, e-mail: huseyn.imanov1991 @gmail.com
Mdqalddd etilenqlikol muhitindd TI3ASS4 birld§mdsinin alinmasina vd fiziki-kimydvi analizind (RFA, DTG, TG, DTA vd SEM) aid ndticdldr verilmi§dir. Mudyydn edilmi§dir ki, hdlledici olaraq etilenqlikoldan vd ilkin komponent kimi TlNO3 vd AS2S5 birld§mdldrinddn istifadd etdikdd 80 °C temperaturda TlsAsS4 birld§mdsi alinir. TI3ASS4 birld§mdsi TNO3 vd AS2S5 birld§mdldrinin 4:15 mol nisbdtinddki qari§iginda formala§ir. 80 °C temperaturda (pH=7-8) alinan TlsAsS4 birld§mdsinin tdrkibindd cuzi miqdarda (~ 0.02 %) sdrbdst kukurd i§tirak edir. Birld§mdni 410 °C -dd ikizonali rejimdd termiki emal etdikdd tdmiz §dkildd ThAsS4 birld§mdsi alinir. Etilenqlikol muhitindd alinmi§ TlsAsS4 birld§mdsinin mikromorfologiyasi oyrdnilmi§dir. Mudyydn edilmi§dir ki, 80 °C temperaturda TlsAsS4 birld§mdsinin nanohissdcikldri formala§ir. Termoqravimetrik analiz ndticdldrind dsasdn ThAsS4 birld§mdsi N2 qazi muhitindd T>460 °Colduqda pargalanir. Agar sozlsr: differensial termoqravimetrik analiz, mdhlul, mikromorfologiya, element analizi, gokmd, tritallium tetratioarsenat
ИССЛЕДОВАНИЕ ПОЛУЧЕНИЯ TlsAsS4 В СРЕДЕ ЭТИЛЕНГЛИКОЛЯ
Г.А. Иманов, К.М. Гусейнов
Институт Природных Ресурсов Нахчыванского филиала НАНА, AZ 7000, ул. Гейдара Алиева. 35. Тел: +994708716976, e-mail: huseyn.imanov1991 @gmail.com
В статье представлены результаты получения и физико-химического анализа (РФА, ДТГ, ТГ, ДТА и СЭМ) TlAsS4 в среде этиленгликоля. Было обнаружено, что при использовании этиленгликоля в качестве растворителя, а TINO3 и AS2S5 в качестве исходных компонентов в соотношении 4:15 мол, TlAsS4 образуется при температуре 80 °С. TlAsS4, полученный при температуре 80 °С (pH = 7-8), содержит небольшое количество (-0.02%) свободной серы. При термообработке соединения при 410 °С в двухзонном режиме получается чистое соединение TlAsS4. Изучена микроморфология полученного TlAsS4. Согласно результатам термогравиметрического анализа, соединение TlAsS4 разлагается в газовой среде N2 при T>460 °С.
Ключевые слова: дифференциальный термогравиметрический анализ, раствор, микроморфология, элементный анализ, седиментация, тетратиоарсенат триталлия
