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Preparation method for rod-like Sc2W3O12 negative thermal expansion material

A negative thermal expansion material, sc2w3o12 technology, applied in chemical instruments and methods, tungsten compounds, inorganic chemistry, etc., can solve the problems of high reaction temperature, long reaction time, affecting the purity of the final product, etc., and achieve simple procedures, easy operation and industrialization Effect

Active Publication Date: 2012-10-24
JIANGSU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003]The traditional method of preparing Sc2W3O12 is the solid phase method , the reaction temperature is high (1100°C), the reaction time is long (>24h), and because WO3 volatilizes at high temperature, the purity of the final product will be affected, and the shape of the product is irregular (Evans J S O, Mary T A, Sleight A W. Journal of Solid State Chemistry, 1998,137:148-160.), while factors such as the morphology and particle size of the constituent materials will have a greater impact on the performance and application of the final product. In recent years, water The preparation of ceramic powder by thermal method has attracted widespread attention. This method is characterized by uniform mixing of reactants and controllable product morphology. At present, there is no preparation of rod-shaped Sc2W3O12 reports

Method used

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  • Preparation method for rod-like Sc2W3O12 negative thermal expansion material
  • Preparation method for rod-like Sc2W3O12 negative thermal expansion material

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Embodiment 1

[0016] Rod-shaped Sc was successfully synthesized by hydrothermal method 2 W 3 o 12 Negative thermal expansion material, raw material: Sc(NO 3 ) 3 · wxya 2 O (analytically pure), H 40 N 10 o 41 W 12 · wxya 2 O (chemically pure), first prepare scandium nitrate and ammonium tungstate into 0.5mol / L and 0.1mol / L solutions respectively, and then use the double drop method to mix the two solutions of scandium nitrate and ammonium tungstate by Sc 3+ :W 6+ The molar ratio was 2:3, and nitric acid solution was added to the mixed solution to adjust the pH=5 under constant stirring, and stirred at 70°C for 3 hours; Seal and heat at 180°C for 10 hours. After the reaction is complete, use a centrifuge to dehydrate. After pouring off the supernatant, wash and centrifuge repeatedly for 3 times, and then dry at 100°C to obtain the precursor; put the precursor in the muffle furnace The final product Sc was obtained after heating at 550 °C for 5 h 2 W 3 o 12 ,Depend on figure ...

Embodiment 2

[0018] Rod-shaped Sc was successfully synthesized by hydrothermal method 2 W 3 o 12 Negative thermal expansion material, raw material: Sc(NO 3 ) 3 · wxya 2 O (analytically pure), H 40 N 10 o 41 W 12 · wxya 2 O (chemically pure), HNO 3 (analytical pure), first prepare scandium nitrate and ammonium tungstate into 1mol / L and 0.05mol / L solutions respectively, dissolve them in deionized water respectively, and use the double drop method to mix the two solutions of scandium nitrate and ammonium tungstate by Sc 3+ :W 6+ Mix at a molar ratio of 2:3, add nitric acid solution to the mixed solution to adjust pH=4 under constant stirring, and stir at 60°C for 4 hours; then transfer the mixed solution to a reaction kettle with a polytetrafluoroethylene liner, Seal and heat at 160°C for 15 hours. After the reaction is complete, use a centrifuge to dehydrate, discard the supernatant, wash and centrifuge repeatedly for 3 times, and then dry at 80°C to obtain the precursor; put th...

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Abstract

The present invention relates to a negative thermal expansion material, and particularly to a preparation method for a rod-like Sc2W3O12 negative thermal expansion material. According to the present invention, a hydrothermal method is adopted to synthesize a negative thermal expansion compound Sc2W3O12 at a low temperature, wherein raw materials comprise Sc(NO3)3.xH2O (analytically pure grade), H40N10O41W12.xH2O (chemically pure grade), and HNO3 (analytically pure grade). The preparation method comprises: respectively dissolving scandium nitrate and ammonium wolframate in deionized water according to a molar ratio of Sc<3+> to W<6+> of 2:3; adopting a double-addition method in a dropwise manner to mixing the resulting two solutions; adding a nitric acid solution to the resulting mixing solution to adjust the pH value to 3-5 while constantly stirring, and uniformly stirring at a temperature of 60-80 DEG C; transferring the resulting mixed solution to a reaction kettle with a polytetrafluoroethylene liner, carrying out sealing heating for 10-15 hours at a temperature of 150-180 DEG C; after completing the reaction, carrying out centrifugal dewatering by using a centrifuge, discarding the supernatant, repeatedly washing and centrifugating 3 times, and then drying at a temperature of 80-110 DEG C to obtain a precursor; placing the precursor in a muffle furnace, and heating at a temperature of 540-800 DEG C to obtain the final product Sc2W3O12. The method of the present invention has advantages of simple procedure, easy operation and easy industrialization.

Description

technical field [0001] The invention relates to negative thermal expansion materials, in particular to a rod-shaped Sc 2 W 3 o 12 The preparation method of negative thermal expansion material adopts hydrothermal method to synthesize negative thermal expansion compound Sc at low temperature 2 W 3 o 12 , can directly obtain a well-crystallized product, avoiding the high temperature treatment in the usual synthesis process. Background technique [0002] sc 2 W 3 o 12 It is a typical negative thermal expansion (NTE) compound material, which has NTE effect in a wide temperature range (at least -263~927°C), and may last until its melting point (~1652°C), while its The phase transition temperature is -263°C, and the phase transition pressure is about 2.7GPa. In addition, Sc 2 W 3 o 12 Exhibits unique electrical properties; these excellent properties enable the negative thermal expansion material to be used alone or to prepare composite materials, thereby precisely contro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G41/00B82Y40/00
Inventor 程晓农朱君君杨娟
Owner JIANGSU UNIV
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