Preparation method of as-reduced ammonium tungsten bronze nanoparticles

Abstract

The invention relates to a preparation method of as-reduced ammonium tungsten bronze nanoparticles and belongs to the field of inorganic oxide materials. Under the condition of solvothermal, organic long-chain high-boiling-point acid is used as reaction medium, an organic tungsten source and organic high-boiling-point amine are used as raw materials, and ammonium tungsten bronze nanoparticles are produced through one-step control in the non-water environment. A sample prepared by the preparation method is hexagonal ammonium tungsten bronze nano-crystal; the size of the nano-crystal is adjusted in a range of 80-500 nanometers; the form of the nano-crystal is even; the particle size distribution is narrow; chemical valence state of the nano-crystal is mixture of W6+ and W5+; the nano-crystal has rich free electrons. In addition, the sample prepared by the preparation method has high capacity of absorbing near infrared; the film containing the nanoparticles is effective in shielding 780-2500 micrometers near infrared and is highly permeable to visible light.

Description

technical field [0001] The invention belongs to the field of preparation of inorganic oxide materials, and relates to a preparation method of reduced ammonium tungsten bronze nano powder. Background technique [0002] Tungsten bronze compounds are an important class of inorganic compounds, in which tungsten ions are represented by W 6+ , W 5+ and W 4+ Equivalent mixed valence states exist so that the overall charge of the compound is balanced. The rich crystal structure, tunnel structure and this special valence state make it have excellent properties, such as electronic and ionic conductivity, superconductivity, optical properties, etc. It is used in secondary batteries, electrochromic, near-infrared absorption and Applications such as chemical sensors have aroused extensive research interest. [0003] At present, the synthesis of tungsten bronze compounds mainly relies on wet chemical method, thermal reduction method and thermal decomposition method. The wet chemical ...

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Problems solved by technology

Due to the poor thermal stability of ammonium tungsten bronze, the decomposition temperature (300°C) is lower than the synthesis temperature, so the thermal reduction method cannot be used to synthesize ammonium tungsten bronze

Ammonium tungsten bronze is synthesized by pyrolysis method by ammonium paratungstate in reducing atmosphere (H 2 or H 2 and N 2 , Ar mixed gas, etc.) and thermally decomposed. In addition to the large particle size of the obtained sample, this method cannot obtain completely pure-phase ammonium tungsten bronze. The ammonium content in the sample is too low and it is easy to be excessively decomposed into tungsten oxide.

[0004] So far, the research so far has not been able to directly obtain pure-phase ammonium tungsten bronze nanopowders, so the obtained micron-sized large particles are usually broken into small particles by ball milling, but such compounds are easily oxidized and degraded during ball milling. Inactivation is easy to decompose, and it is also accompanied by disadvantages such as decreased crystallization performance, so there is still no way to directly obtain nano-ammonium tungsten bronze powder in one step

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