Phase-transition intelligent materials with adjustable phase-transition temperature and process for preparing same

Abstract

The invention relates to an intelligent phase-change material with adjustable phase-change temperature and its preparing process, which comprises making doped vanadium dioxide precursor through liquid phase precipitation method, carrying out filtering, scouring, drying, heating and crystallizing. The crystal grain dimension of the obtained phase-change material is less than 100 nanometers, thus can be applied into intelligent window coating material and temperature measurement resistors.

Description

technical field [0001] The invention relates to the field of chemical industry, and relates to a phase-change smart material with adjustable phase-change temperature and a preparation method thereof. Background technique [0002] Scientists have found that vanadium dioxide is equal to (T C =68°C) will undergo crystal transformation from square structure to monoclinic structure, with reversible semiconductor-metal phase transition, low temperature phase has semiconductor properties, high infrared transmittance and low reflectivity, high temperature phase It has metallic properties, low infrared transmittance and high reflectivity, so it is a thermochromic material that can be applied to solar temperature control devices, photoelectric switch materials, thermistor materials, optical information storage, laser Blinding weapon protection devices, large-area thermochromic glass curtain walls, energy-saving coatings, polarizers and variable reflectors, etc. However, because its ...

AI Technical Summary

Problems solved by technology

For example, U.S. Patent No. 6,358,307 reports a method for synthesizing tungsten-doped vanadium dioxide. The synthesis route is to add soluble ammonium tungstate solution in ammonium metavanadate, then heat and drop hydrochloric acid solution, ammonium tungstate and ammonium metavanadate After condensation, a mixture of ammonium paratungstate (NH 4 ) 2 V 6 o 16 Paste liquid, filter, wash and dry the precipitate, put it in a sealed tube furnace and heat it to decompose to obtain doped vanadium dioxide; this method may not be uniform due to the fact that ammonium tungstate and ammonium vanadate are not mixed at the atomic level. And the decomposition process is a redox process, it is possible to get V n o 2n+1 and V n o 2n-1 Two sets of non-integer ratio compounds, which make VO 2 The valence state is not accurate enough, and the powder is stacked together, relying on NH 3 Diffusion is difficult to ensure the uniformity of the product

Chinese patent CN 1279211A reports a preparation method of vanadium dioxide nano-powder and nano-ceramic, adopting dropwise excess saturated ammonium bicarbonate solution in vanadyl dichloride solution to form basic ammonium vanadyl carbonate (IV) crystals , put the crystalline material in a tube furnace, heat and decompose it in a nitrogen stream containing a small amount of oxygen to obtain vanadium dioxide powder; this method is due to the fact that the decomposition gas contains NH 3 , while vanadium dioxide strongly adsorbs ammonia at high temperature and undergoes a reduction reaction, and the powder is stacked together, it is difficult to ensure the uniformity of the product by carrier gas diffusion, and it is easy to obtain a non-integral compound, which makes vanadium dioxide lose its low-temperature phase transition performance

Images