RU2089491C1 - Method of producing tin hypothiophosphate or indium ortho-thiophosphate - Google Patents

Abstract

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to method of producing tin (II) hypothiophosphate and indium (III) ortho-thiophosphate. Process is carried for two stages for 20- -30 min time-lag at each stage and at intermediate cooling to the room temperature and product grinding. Synthesis of tin thiophosphate and indium thiophosphate is carried out at 450-550 C and 350-450 C, respectively. Yield of products is 98%. Piezosensitivity of thin films (h is about 5-8 mcm) spray-coated by the proposed method is γ about (5.6-6.0) x 10^-7 V/Pa and relative dielectric permittivity ε $\genfrac{}{}{0ex}{}{\text{т}}{\text{33}}$ /ε₀ is about 360-400 under condition of volume excitement at low frequencies. New method ensures to decrease the cost of synthesis of tin hypothiophosphate and indium ortho-thiophosphate by 5.8- and 1,4-fold, respectively. Synthesized compounds were used in semiconductive, piezoelectronic and radioelectronic industries. Synthesis involves new combination of the parent reagents reacting with phosphorus sulfide and sulfur at heating in air and the use of metal oxides. EFFECT: improved method of synthesis, improved quality of the end products. 4 tbl

Description

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 /, JnPS 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 following methods belong to low-temperature methods: 1. exchange interaction between solutions of a metal salt and a water-soluble 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 for several hours at a temperature of 350-500 ^o C in an inert 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 sulfides (phosphides) of metals with sulfides of phosphorus / 6 /; 3. reacting the metal with sulfur and a sulfide of phosphorus P ₄ S _10/7 /.

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 and phosphorus sulfides as sealed reagents in sealed ampoules.

 The aim of the invention is to reduce the cost of the synthesis process through the use of a cheaper starting reagent.

The goal is achieved in that in a method involving the interaction of stoichiometric amounts of metal, phosphorus and sulfur compounds in air in two stages with exposure at a temperature of 350-450 ^o C in the case of InPS ₄ and 450-550 ^o C in the case of Sn ₂ P ₂ S ₆ 20-30 minutes at each stage with intermediate cooling to room temperature and grinding the product, a distinctive feature is that the starting metal compounds are used SnO and In ₂ O ₃ oxides, and phosphorus sulfide P ₄ S ₁₀ as phosphorus compounds.

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. Выход продукта составляет примерно 98 от теоретически возможного. Общее время взаимодействия исходных реагентов 40-60 мин. Дополнительные операции (приготовление шихты, загрузка ее в ампулу, нагревание печи до необходимой температуры, перетирание спеченной массы) также занимают около часа, поэтому процесс синтеза длится в общей сложности 2 ч.The method is as follows. The metal oxide powder (grade "h") is mixed with powders of phosphorus sulfide 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 Sn ₂ P ₂ S ₆ ) or 350-450 ^o C (for InPS ₄ ) for 20-30 minutes In this case, fusible sulfur and phosphorus sulfide form a liquid phase, which interacts with solid metal oxide, forming the thiophosphate of the corresponding metal. The total reactions of the formation of 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 product yield is approximately 98 of the theoretically possible. The total reaction time of the starting reagents is 40-60 minutes. Additional operations (preparation of the charge, loading it into the ampoule, heating the furnace to the required temperature, grinding the sintered mass) also take about an hour, so the synthesis process lasts a total of 2 hours.

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 результатом, полученным на пленках на основе Sn₂P₂S₆, полученного по способу-прототипу (табл. 1).Example 1. Obtaining tin hypothiophosphate Sn ₂ P ₂ S ₆ . Phosphorus and sulfur sulfide powders (osch grade) are mixed in a stoichiometric ratio (according to reaction 1) with SnO tin oxide powder (grade h), for example, 2.26 g of P ₄ S ₁₀ and 0.65 g of sulfur are mixed with 2.74 g of SnO. After thorough mixing, the mixture is heated in a sealed ampoule at a temperature of ≈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. The yield of the product is 98.0 X-ray phase analysis (XRD) shows 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 literature data:
The product is synthesized by the proposed method (Mat. Res. Bull. 1974, 9, N 4, 401-410)

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 result 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.

Аналогично примерам 1 и 2 были проведены синтезы Sn₂P₂S₆ и InPS₄ при других соотношениях исходных компонентов, температурах и времени взаимодействия. Полученные результаты сведены в табл. 2-4.Example 2. Obtaining orthothiophosphate indium JnPS ₄ . Powders of phosphorus sulfide 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, 2.03 g of P ₄ S ₁₀ and 1.32 g of sulfur are mixed with 2.53 g of In ₂ O ₃ . After thorough mixing, 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 a 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 the crystal lattice parameters were determined, which are in good agreement with published data:
The product is synthesized by the proposed method (Acta Cryst. 1978, B 34, N 4, 1097-1101)

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.

As can be seen from the table. 2, the optimum are the ratios of the starting components, which differ from stoichiometry by more than 5 molecular ones (examples 3-7 and 12-16 of table 2). In this case, as a result of synthesis, thiophosphate not contaminated with impurities is formed with a yield of about 98
When you go beyond the lower boundary of the specified interval (examples 1, 2 and 10, 11), not all metal oxide interacts, polluting the synthesis product, the yield of thiophosphate decreases by about 10
When you go beyond the upper boundary of the proposed concentration range (examples 8, 9, 17, 18), not all sulfur and phosphorus sulfide bind to thiophosphate, the synthesis product is contaminated with phosphorus sulfides, the yield of the target product is reduced to 85
As can be seen from the table. 3, the best results were obtained during the synthesis of 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 table 3) . Under these conditions, pure thiophosphate phases are obtained; their yield is about 98
At temperatures below 450 ^o C (example 1) or 350 ^o C (example 6), the reaction does not proceed to the end. 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 59-64 of the theoretically possible.

Temperatures exceeding 550 ^o C (for Sn ₂ P ₂ S ₆ ) or 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, 10), thiophosphates are contaminated with metal sulfides, the yield decreases to 82-84
As can be seen from the table. 4, a sufficient interaction time of metal oxides, phosphorus sulfide and sulfur at the optimum synthesis temperature is 40-60 minutes (examples 2-4, 7-9 of table 4). In this case, with a yield of 98, thiophosphate phases free of impurities are formed.

If the interaction lasts less than 40 min, the synthesis does not proceed to the end: along with the phase of thiophosphates, the XRD detects metal oxides and phosphorus sulfides (examples 1, 6), the yield of thiophosphates does not exceed 80
The interaction time in excess of 60 minutes (examples 5, 10) is impractical for economic reasons.

As mentioned earlier, the reaction of the interaction of metal oxides with phosphorus sulfide and sulfur is heterogeneous, because sulfur melts at ≈120 ^o C, phosphorus sulfide P ₄ S ₁₀ at ≈300 ^o C, and oxides SnO and In ₂ O ₃ at 1930 and 2000 ^o C, respectively. Due to this, the process of formation of thiophosphates occurs on the contact surface of metal oxides with the melt. Intermediate grinding of the synthesis products is designed to homogenize the reaction mass, thus ensuring the completeness of the interaction of the starting products.

When implementing the synthesis of Sn ₂ P ₂ S ₆ and InPS ₄ in one stage, the process time is at least 2-3 hours.

 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 in two stages exceeds 60 minutes. The increase in the interaction time at the first stage over 30 min practically does not lead to a reduction 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)

The method of producing tin hypothiophosphate Sn ₂ P ₂ S ₆ or indium orthothiophosphate InPS ₄ , comprising the interaction of stoichiometric amounts of the corresponding metal compound, the phosphorus and sulfur compounds 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 Matelli compounds use SnO or In ₂ O ₃ oxides, and P ₄ S _{1 0} as the phosphorus compound.

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