RU2089492C1 - Method of synthesis of tin hypothiophosphate or indium ortho-thiophosphate - Google Patents

Abstract

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to method of synthesis of tin hypothiophosphate Sn₂P₂S₆ and indium ortho-thiophosphate InPS₄. Process is carried out for two stages at 20-30 min time-lag at each stage and intermediate cooling to the room temperature and product grinding. Synthesis of tin hypothiophosphate and indium ortho-thiophosphate is carried out at 450-550 C and 350-450 C, respectively. Yield is 98%. New method of synthesis ensures to decrease the cost of synthesis of tin hypothiophosphate and indium ortho-thiophosphate by 5.8- and 1.4-fold, respectively. Piezosensitivity of thin films (h is about 5-8 mcm) spray-coated from Sn₂P₂S₆ synthesized by the proposed method is γ about (5.5-6.0) x 10^-7 V/Pa and relative dielectric permittivity ε₃₃/ε₀ about 360-400 at low frequency of volume excitement. The synthesized compounds were used in semiconductive, piezoelectronic and radioelectronic industries. EFFECT: improved method of synthesis. 4 tbl

Description

A method of producing tin hypothiophosphate Sn ₂ P ₂ S ₆ or indium orthothiophosphate InPS ₄ .

The invention relates to the production of tin hypothiophosphate and indium orthothiophosphate, which can be used in semiconductor, piezoelectric and electronic equipment (for example, Sn ₂ P ₂ S ₆ as sensitive elements of pyroelectric radiation detectors / 1 /, InPS ₄ for parametric generation with frequency tuning / 2 /.

Methods for producing hypo- and orthothiophosphates (for brevity, hereinafter referred to as thiophosphates) are divided into low-temperature (water) and high-temperature. The low-temperature methods include the following: 1. exchange interaction between solutions of a metal salt and an alkali metal thiophosphate (for example, Na ₄ P ₂ S ₆ ) / 3 /; 2. reacting metal sulphide Me ₂ S with phosphorus trichloride PCl _3/4 /.

The disadvantages of aqueous synthesis methods include the need to use compounds that are not commercially available (Na ₄ P ₂ S ₆ , PCl ₃ ) as initial reagents, and the need to transfer the amorphous product resulting from the synthesis to a crystalline state by annealing it during several hours at temperatures of 350-500 ^o C in an inert anhydrous atmosphere (i.e. in a sealed ampoule).

 The following high-temperature methods for the synthesis of thiophosphates are known: 1. interaction of simple substances Me, P, S / 5 /; 2. The interaction of metal sulfides (phosphides) with phosphorus sulfides / 6 /.

All high-temperature syntheses are carried out in sealed quartz vacuum ampoules and are characterized by complex temperature regimes designed to prevent the explosion of ampoules. They last from several days to several months, require the use of relatively high temperatures (500-900 ^o C) and are explosive due to the use of phosphorus, sulfur, phosphorus sulfides in sealed ampoules as initial reagents.

 The aim of the invention is to reduce the cost of the process by using a more affordable and cheaper starting reagent.

The goal is achieved in that in a method comprising the interaction of stoichiometric amounts of metal compounds, red phosphorus and sulfur in air in two stages with exposure at a temperature of 350-450 ^o C in the case of indium orthothiophosphate and 450-550 ^o C in the case of tin hypothiophosphate at 20- 30 minutes at each stage with intermediate cooling to room temperature and grinding of the product, a distinctive feature is that the oxides SnO and In ₂ O ₃ are used as initial data for metal compounds.

 The method is as follows.

После охлаждения до комнатной температуры полученную спеченную массу перетирают в порошок, который повторно нагревают в незапаянной ампуле при температурах 450-550 ^oC (350-450) ^oC в течение 20-30 мин. Общее время взаимодействия исходных компонентов составляет 40-60 мин. Выход продукта - примерно 98 от теоретически возможного.The metal oxide powder (grade "h") is mixed with powders of red phosphorus and sulfur (grade "osch") in a stoichiometric ratio and carefully rubbed. The resulting mixture is heated in a sealed ampoule at temperatures of 450-550 ^o C (for tin hypothiophosphate) or 350-450 ^o C (for indium orthothiophosphate) for 20-30 minutes In this case, phosphorus reacts with sulfur to form liquid phosphorus sulfides, which interact with solid metal oxide, forming the thiophosphate of the corresponding metal. The total reactions of the formation of metal thiophosphates can be represented as follows:

After cooling to room temperature, the resulting sintered mass is ground into a powder, which is reheated in a sealed ampoule at temperatures of 450-550 ^o C (350-450) ^o C for 20-30 minutes The total interaction time of the starting components is 40-60 minutes The product yield is approximately 98 of the theoretically possible.

Дополнительно при условиях, описанных в примере 1, был синтезирован Sn₂P₂S₆, который использовался в качестве основы для напыления тонких пленок (h≈5-8 мкм). На пленках была измерена пьезочувствительность γ на низких частотах при объемном возбуждении и относительная диэлектрическая проницаемость ε $\genfrac{}{}{0ex}{}{\text{т}}{\text{33}}$ /ε₀ и сопоставлены с результатами, полученными на пленках на основе Sn₂P₂S₆, полученного по способу-прототипу (табл. 1).Example 1. Obtaining tin hypothiophosphate Sn ₂ P ₂ S ₆ . Powders of red phosphorus and sulfur (osch grade) are mixed in a stoichiometric ratio (according to reaction 1) with SnO powder (ч grade ’) (for example, 0.69 g of phosphorus and 2.50 g of sulfur are mixed with 3.00 g of SnO ) and rubbed thoroughly. The resulting mixture is heated in a sealed ampoule at 500 ^o C for 25 minutes After cooling to room temperature, the sintered mass is ground into powder, which is reheated in air at 500 ^° C for 25 minutes. Product yield 98.1 Product identification was carried out on the basis of x-ray phase analysis (XRD). X-ray powder diffraction showed the presence in the synthesis product of a single phase of tin hypothiophosphate, for which the crystal lattice parameters were determined, which are in good agreement with the published data:
The product is synthesized by the proposed method. Analog / 5 /

Additionally, under the conditions described in example 1, Sn ₂ P ₂ S ₆ was synthesized, which was used as the basis for the deposition of thin films (h≈5-8 μm). On the films, the piezosensitivity γ at low frequencies under volume excitation and the relative permittivity ε $\genfrac{}{}{0ex}{}{\text{t}}{}$$\genfrac{}{}{0ex}{}{}{\text{33}}$ / ε ₀ and compared with the results obtained on films based on Sn ₂ P ₂ S ₆ obtained by the prototype method (table. 1).

As can be seen from the table. 1, the quality of thin films based on Sn ₂ P ₂ S ₆ obtained by the proposed method is not inferior to the quality of films based on Sn ₂ P ₂ S ₆ synthesized by the prototype method.

Обработка оптимального соотношения исходных компонентов, температуры и времени взаимодействия.Example 2. Obtaining orthothiophosphate indium InPS ₄ . Powders of red phosphorus and sulfur (brand "osch") are mixed in a stoichiometric ratio (according to reaction 2) with a powder of indium oxide (III) (brand "h"). For example, 0.57 g of phosphorus and 2.78 g of sulfur are mixed with 2.53 g of In ₂ O ₃ and carefully triturated. The mixture is heated in a sealed ampoule at 400 ^o C for 25 minutes After cooling to room temperature, the sintered mass is ground into powder, which is reheated in air at 400 ^° C for 25 minutes. The product yield of 97.8 XRD revealed an indium orthothiophosphate phase, not contaminated with any impurities, for which crystal lattice parameters were determined that are in good agreement with published data (Acta Cryst. 1978, B 34, N 4, 1097-1101):
The product is synthesized by the proposed method. Literature data

Processing the optimal ratio of the starting components, temperature and interaction time.

Similarly to examples 1 and 2, syntheses of Sn ₂ P ₂ S ₆ and InPS ₄ were carried out at other ratios of the starting components, temperatures, and reaction times. The results are summarized in table. 2-4.

 1. The rationale for the proposed concentration range.

As can be seen from the table. 2, the ratios of the starting components are optimal, which differ from stoichiometry by no more than 5 molecular (examples 3-7 and 12-16 of table 2). In this case, as a result of the synthesis, thiophosphates not contaminated with impurities are formed with a yield of about 98. When leaving the lower boundary of the indicated concentrated interval (examples 1, 2, 10, 11), not all metal oxide interacts with phosphorus sulfides, polluting the synthesis product, yield thiophosphate decreases by about 10 When you go beyond the upper limit of the proposed interval (examples 8, 9, 17, 18) not all phosphorus and sulfur bind to thiophosphate, the synthesis product is contaminated with phosphorus sulfides, the yield of the target product is reduced to 85
2. Justification of the proposed temperature range.

As can be seen from the table. 3, the best results were obtained when synthesizing Sn ₂ P ₂ S ₆ at temperatures of 450-550 ^o C (examples 2-4 table. 3), and the synthesis of InPS ₄ at 350-450 ^o C (examples 7-9). In this case, pure phases of thiophosphates are formed, the yield of products is approximately 98. At temperatures below 450 ^o C (example 1), the reaction between tin oxide and phosphorus sulfides does not proceed to the end, as does the reaction of indium oxide with phosphorus sulfides at 350 ^o C (example 6). The XRD, along with the Sn ₂ P ₂ S ₆ and InPS ₄ phases, fixes the SnO, In ₂ O ₃ and phosphorus sulfide phases. The output of thiophosphates is only 64-65 of the theoretically possible. Temperatures exceeding 550 ^o C (for Sn ₂ P ₂ S ₆ ) and 450 ^o C (for InPS ₄ ) are impractical because at these temperatures, the incongruent melting of the synthesis products begins, accompanied by the evaporation of volatile phosphorus sulfides (examples 5 and 10), the yield of thiophosphates decreases by 14-15
3. Justification of the interaction time of the starting components.

 As can be seen from the table. 4, a sufficient interaction time of metal oxides, phosphorus and sulfur at the optimum synthesis temperature is 40-60 minutes (examples 2-4, 7-9 of table 4). If the interaction lasts less than 40 minutes, the synthesis does not proceed to the end: along with the phase of thiophosphates, the XRD detects metal oxides and phosphorus sulfides (examples 1 and 6). The product yield does not exceed 65. The interaction time in excess of 60 minutes (examples 5 and 10) is impractical for economic reasons.

 4. The rationale for the two-stage synthesis.

As mentioned earlier, the reaction of the interaction of metal oxides with phosphorus sulfides (formed during the interaction of phosphorus and sulfur) is heterogeneous, because phosphorus sulfides melt at 300 ^o C, and oxides SnO and In ₂ O ₃ at 1930 ^o C and 2000 ^o C, respectively. Due to this, the process of formation of thiophosphates occurs on the contact surface of metal oxides with a melt of phosphorus sulfides. Intermediate grinding of the synthesis products is designed to homogenize the reaction mass, thus ensuring the completeness of the interaction of the starting reagents. When implementing the synthesis of thiophosphates in one stage, the process time is at least 2-3 hours; moreover, the completeness of the reaction is not always observed.

 5. Justification of the duration of the interaction time at each stage.

 The best results were obtained with the same interaction time at each stage, equal to 20-30 minutes. If the interaction time in the first stage is less than 20 minutes, then the completion of the process in the second stage is achieved in a time many times greater than 30 minutes, and the total interaction time of the two stages exceeds 30 minutes. The increase in the time of the first stage over 30 minutes practically does not lead to a reduction in the necessary interaction time in the second stage and therefore is not economically justified. If, under the optimal conditions of the first stage, the interaction time in the second stage is less than 20 minutes, then the interaction does not proceed to the end: along with the phases of thiophosphates, the XRD fixes the phases of the initial metal oxides and phosphorus sulfides. The interaction time in the second stage, exceeding 30 minutes, is impractical for economic reasons.

Thus, a new method for producing tin hypothiophosphate Sn ₂ P ₂ S ₆ and indium orthothiophosphate InPS _{4 is} proposed. The main advantage of the proposed method compared to the prototype is the reduction in the cost of the synthesis of tin hypothiophosphate by 5.8 times, and indium orthothiophosphate by 1.4 times due to the use of a more affordable and cheaper starting reagent.

Claims (1)

A method of producing tin hypothiophosphate Sn ₂ P ₂ S ₆ or indium orthothiophosphate InPS ₄ , comprising reacting stoichiometric amounts of a compound of the corresponding metal, red phosphorus and sulfur in air in two stages with exposure at a temperature of 350 to 450 ^o C in the case of obtaining indium orthiophosphate and at a temperature of 450 -550 ^o C in the case of obtaining tin hypothiophosphate for 20 30 min at each stage with intermediate cooling to room temperature and grinding the product, characterized in that, in order to reduce the cost of the process, as the source compounds metal ions use SnO or In ₂ O ₃ oxides.

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