Preparation method for rod-like Sc2W3O12 negative thermal expansion material

Abstract

The invention relates to a negative thermal expansion material, in particular to a preparation method of a rod-shaped Sc2W3O12 negative thermal expansion material. The invention adopts the hydrothermal method to synthesize the negative thermal expansion compound Sc2W3O12 at low temperature, and the raw materials used are: Sc(NO3)3 xH2O (analytical pure), H40N10O41W12 xH2O (chemical pure), HNO3 (analytical pure). Dissolve scandium nitrate and ammonium tungstate in deionized water at a molar ratio of Sc3+:W6+ of 2:3, mix the two solutions of scandium nitrate and ammonium tungstate by double drop method, and add to the mixed solution under constant stirring Adjust pH=3~5 with nitric acid solution, stir evenly at 60~80°C; transfer the mixed solution into a reaction kettle lined with polytetrafluoroethylene, seal and heat at 150~180°C for 10~15h, and the reaction is complete Finally, use a centrifuge for centrifugal dehydration, pour off the supernatant, wash and centrifuge repeatedly for 3 times, and then dry at 80-110°C to obtain the precursor; place the precursor in a muffle furnace and heat it at 540-800°C The final product Sc2W3O12 is obtained. The method has the advantages of simple procedure, easy operation and 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...

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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

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