Preparation methods and uses of doped VIB group metal oxide nanoparticles or dispersions thereof

Abstract

The present invention is related to a method for preparing VIB Group metal oxide particles or dispersions, wherein the VIB Group metal is tungsten or molybdenum. The methods include: 1) providing precursors of VIB Group metal oxide, reductants and supercritical fluids. 2) said VIB Group metal oxide particles, or dispersions are obtained by the reaction between said metal oxide precursors, and reductants are under supercritical state in said supercritical fluids. Especially, said VIB Group metal oxide can be tungsten bronze, molybdenum bronze, or tungsten and molybdenum bronze which can be present by the formula A.sub.xB.sub.yMO.sub.z. Wherein, A represents element exists in the form of dopant cation; and B represents element exists in the form of dopant anion; O represents oxygen; 0?x?1, 0?y?1, 0<x+y?1, and 2?z?3. The said VIB Group metal oxide particles and dispersions can be applied to the glasses of houses, buildings, automobiles, ships etc, with high transparency and NIR and UV lights shielding properties, by which the control of sunlight and heat radiation can be achieved.

Claims

1. A method for preparing VIB Group metal oxide particles or a dispersion thereof, the method comprising: 1) reacting a salt solution of the VIB Group metal with a precipitating agent solution to produce colloid particles of an acid of the VIB Group metal; 2) removing impurities from the colloid particles to obtain purified colloid particles; and 3) reacting the purified colloid particles with a reductant in a supercritical fluid under a supercritical state to obtain the VIB Group metal oxide particles or the dispersion thereof, wherein the supercritical fluid under the supercritical state is substantially free of a solvent that is not a supercritical fluid under the supercritical state, wherein the VIB Group metal is molybdenum, tungsten, or both, and the acid of the VIB Group metal is tungstic acid, molybdic acid, or both, wherein a concentration of the VIB Group metal oxide particles or the dispersion thereof in the supercritical fluid is in the range of 0.25 mol/L to 0.33 mol/L, and wherein the supercritical state has a temperature ranging from 150-400? C. and a pressure ranging from 1-30 atm.

2. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the VIB Group metal oxide is selected from the group consisting of tungsten bronze, molybdenum bronze, and tungsten-molybdenum bronze, wherein the VIB Group metal oxide has an empirical formula: A.sub.xB.sub.yMO.sub.z, wherein M is tungsten atom, molybdenum atom, or combinations thereof; A is a dopant element in form of cation; B is a dopant element in form of anion; O is oxygen; 0?x?1, 0?y?1, 0<x+y?1, 2?z?3; wherein A is ammonium or one or more elements selected from elements of main-groups and sub-groups, and B is one or more elements selected from elements of main-groups and sub-groups.

3. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 2, wherein a portion of said M has a valence of +6 and the rest of said M has a valence of lower than +6.

4. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein one or more of the precursor of VIB Group metal oxide, the reductant, and the supercritical fluid contains a VIIIB Group metal or a compound thereof as a catalyst to catalyze the reaction.

5. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 4, wherein the one or more of the precursor of VIB Group metal oxide, the reductant and the supercritical fluid contains a pH regulator, and the pH regulator is selected from the group consisting of inorganic acids, inorganic bases, organic acids, organic bases, and combinations thereof.

6. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 5, wherein the reductant, the catalyst, and the pH regulator is of the supercritical state and used as at least a part or all of the supercritical fluid in the reaction.

7. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the VIB Group metal oxide particles have an average particle size of less than or equal to 10 ?m.

8. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the VIB Group metal oxide particles have a steepness ratio of less than or equal to 3 for particle size distribution.

9. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the supercritical fluid is a supercritical fluid with a critical temperature of below 650? C.

10. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the supercritical fluid is selected from a group consisting of water, ammonia, alcohols, ketones, esters, aldehydes, amines, hydrocarbons, ethers, heterocycles, organic acids and combinations thereof.

11. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, wherein the reaction in step 3) is performed under a condition that the supercritical fluid has a Reynolds number of 2000-200000.

12. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, further comprising: 4) adding a surfactant to the one or more of the precursor of VIB Group metal oxide, the reductant and the supercritical fluid in step 2) or to the VIB Group metal oxide particles or dispersions as obtained in step 3).

13. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 12, wherein the surfactant is selected from the group consisting of non-silane surfactants, silane coupling agents, titanate coupling agents, and combinations thereof.

14. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 1, further comprising: 5) separating the VIB Group metal oxide particles or dispersion thereof of step 3) from an impurity in the supercritical fluid, wherein the separation is performed in manner of liquid-liquid phase transfer, precipitation and/or filtration.

15. The method for preparing the VIB Group metal oxide particles or dispersion thereof according to claim 14, further comprising: 6) redispersing the separated VIB Group metal oxide particles in a medium to form a dispersion of the VIB Group metal oxide particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 1. Figures are just used for illuminating examples and principles, not for limiting definitions of the present invention.

(2) FIGS. 1(a)-1(c) show plan sketches of three crystal structures of VIB Group metal oxide particles, in which FIG. 1(a) shows a cubic structure; FIG. 1(b) shows a tetragonal structure; FIG. 1(c) shows a hexagonal structure.

(3) FIG. 2(a) and FIG. 2(b) show a process sketch of some embodiments according to the present invention, in which FIG. 2(a) shows a process sketch of a method for preparing doped W/Mo bronze particles and dispersions thereof; FIG. 2(b) shows a process sketch of another method for preparing doped W/Mo bronze particles and dispersions thereof.

(4) FIG. 3(a) and FIG. 3(b) show SEM pictures of nano-cesium tungsten bronze particles, in which the SEM pictures have 100 thousand times amplification, FIG. 3(a) shows a SEM picture of product of Example 1.1, and FIG. 3(b) shows a SEM picture of product of Comparison Example 1.2.

(5) FIG. 4 shows a XRD picture of cesium tungsten bronze particles of Example 1.1.

(6) FIG. 5 shows a XRD picture of sodium cesium tungsten-molybdenum bronze particles of Example 6.2.

(7) FIG. 6(a) and FIG. 6(b) show a DLS picture of Example 7.1 (FIG. 6(a)) and a DLS picture of Comparison Example 7.1 (FIG. 6(b)).

(8) FIG. 7(a) and FIG. 7(b) show ultraviolet-visible light-infrared spectrums of the diluted dispersion of nano-tungsten bronze, in which FIG. 7(a) shows a ultraviolet-visible light-infrared spectrum of the diluted dispersion of Example 8.1. In FIG. 7(b), curve a is a ultraviolet-visible light-infrared spectrum of the cesium tungsten bronze dispersion (0.5 wt %) of Example 7.1 diluted by butyl acetate; curve b is a ultraviolet-visible light-infrared spectrum of the rubidium tungsten bronze dispersion (0.5 wt %) of Example 2.5 diluted by butyl acetate; curve c is a ultraviolet-visible light-infrared spectrum of the potassium tungsten bronze dispersion (0.5 wt %) of Example 2.4 diluted by butyl acetate; curve d is a ultraviolet-visible light-infrared spectrum of sodium tungsten bronze dispersion (0.5 wt %) of Example 2.3 diluted by butyl acetate.

(9) FIG. 8(a) 8(c) show ultraviolet-visible light-infrared spectrums of paintings coated on glass of Example 8.4, in which FIG. 8(a) is a comparison of ultraviolet-visible light-infrared spectrums of blank PET film and ATO coated PET film, FIG. 8(b) is a comparison of ultraviolet-visible light spectrums of ATO coated PET film and TB painting coated PET film, and FIG. 8(c) is a comparison of ultraviolet-visible light-infrared spectrum of ATO coated PET film and TB painting coated PET film.

DETAILED DESCRIPTION OF THE DRAWINGS

(10) FIG. 2(a) shows a process sketch of a method for preparing doped W/Mo bronze particles and dispersions thereof. First, a tungsten/molybdenum metal salt solution (12) (for instance, sodium tungstate solution) reacted with a precipitating agent solution (14) (for instance, hydrochloric solution) in a precipitation reaction region (10) (beaker, flask, reaction kettle), at the same time, a shear force was provided with the mixture during the mixing and precipitation reaction step, the precipitation reaction region (10) was kept at certain temperature (for instance, 0? C.-100? C., room temperature) and certain pressure (for instance, ordinary pressure) for a period of time (for instance, 0.1-24 h, about 1 h); after that, a tungsten/molybdenum bronze precursor (for instance, tungstic acid) was obtained after separation step (20) to remove impurities (22). Then, the obtained tungsten/molybdenum bronze precursor, a dopant and/or reductant (32) and optionally a pH-modifier (34) were reacted in a high-temperature and high-pressure region (30) for a period of time (for instance, 0.1-24 h, about 6 h), and a shear force was provided with the mixture during the high-temperature and high-pressure reaction step so as to form doped tungsten/molybdenum bronze particles; after that, a surfactant (42) was added to coat the particles (40), and the doped tungsten/molybdenum bronze particles (54) after separation (50) to remove impurities (52). A doped tungsten/molybdenum bronze dispersion (66) with near-infrared shielding property was obtained by adding a solvent (64) to redisperse (60) the doped tungsten/molybdenum bronze particles (54).

(11) FIG. 2(b) shows a process sketch of another method for preparing doped W/Mo bronze particles and dispersions thereof, in which a tungsten/molybdenum meal salt solution (12) (e.g., sodium tungstate) was treated with a cation-exchange column (10) to obtain a tungstic/molybdic acid solution which acted as a precursor of tungsten/molybdenum bronze, while the residual steps were similar to the corresponding steps of the process shown in FIG. 2(a).

Specific Models for Carrying Out the Invention

(12) The present invention is further illustrated with the followings examples. The examples are used to illustrate the present invention, rather than put a limit on the present invention.

Example 1

Example of Synthesis of Cesium Tungsten Bronze Nanoparticles

Example 1.1

(13) 200 ml of 0.5 mol/L NaWO.sub.4 aqueous solution was prepared, and then the solution and 97 ml of 3 mol/L hydrochloric acid solution were mixed and reacted at room temperature to obtain a light yellow precipitate. The resultant suspension was subjected to liquid-solid separation, and the resultant solid particles were washed with water and ethanol for 3 times respectively. The washed solid colloid particles were added in 300 ml of ethanol solution which contained 1 mol/L citric acid and stirred, then 50 ml of ethanol solution which contained 0.3 mol/L cesium carbonate was added under stirring condition, the agitation was kept for 1 h. Finally, the mixture was transferred to an enclosed reaction vessel with a stirrer and reacted for 12 h under a supercritical condition of 250? C. and 6.8 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results were shown in FIG. 3 and FIG. 4. FIG. 3 (a) showed the SEM result, indicating that the cesium tungsten bronze particles were short rod-shaped particles which were 60-80 nm in length and 20-40 nm in width. On the basis of EDS elemental analysis, the atomic ratio Cs/W was about 0.327 which was in good agreement with the theoretical value of 0.33. BET analysis demonstrated the specific surface area of the product was 65.36 m.sup.2/g. FIG. 4 showed the XRD result, indicating that the crystal structure of the product was complete hexagonal (JCPDS No. 83-1334) tungsten bronze without WO.sub.3 or WO.sub.3-x impurity peak.

Example 1.2

(14) 200 ml of 0.5 mol/L NaWO.sub.4 aqueous solution was prepared, and then the solution and 97 ml of 3 mol/L hydrochloric acid solution were mixed and reacted at room temperature to obtain a light yellow precipitate. The resultant suspension was subjected to liquid-solid separation, and the resultant solid particles were washed with water and ethanol for 3 times respectively. The washed solid colloid particles were added in 300 ml of ethanol solution and stirred, then 100 ml of ethanol solution which contained 0.3 mol/L cesium hydroxide was added under stirring condition, an amount of acetic acid was used to neutralize cesium hydroxide, and the agitation was kept for 1 h. Finally, the mixture solution was transferred to an enclosed reaction vessel with a stirrer and reacted for 6 h under a supercritical condition of 280? C. and 7.5 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The results showed that the crystal structure of the product was similar to that of Example 1.1, indicating complete hexagonal (JCPDS No. 83-1334) tungsten bronze. SEM results showed that the obtained cesium tungsten bronze particles were short rod-shaped particles which were 50-70 nm in length and 15-30 nm in width, while the BET analysis demonstrated the specific surface area of the product was 70.53 m.sup.2/g.

Example 1.3

(15) 500 ml of 0.15 mol/L tungsten hexachloride ethanol solution was prepared, 100 ml of cesium hydroxide monohydrate ethanol solution was added in a ratio of Cs:W=0.4 at room temperature and stirring conditions, then added with 100 ml of acetic acid, and the agitation was kept to obtain a homogeneous mixture. The mixture was transferred to an enclosed reaction vessel with a stirrer and reacted for 10 h under a supercritical condition of 260? C. and 7.0 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The results showed that the crystal structure of the product was similar to that of Example 1.1, indicating complete hexagonal (JCPDS No. 83-1334) tungsten bronze. The morphology and size of the particles were also similar to those of Example 1.1. The BET analysis demonstrated the specific surface area of the product was close to that of Example 1.1.

Example 1.4

(16) 200 ml of 0.5 mol/L NaWO.sub.4 aqueous solution was prepared, and sodium ions were removed by a styrene-cation exchange resin to obtain 0.5 mol/L tungstic acid solution, then the 200 ml of 0.5 mol/L tungstic acid solution was stirred and simultaneously added with 50 ml of 0.3 mol/L cesium hydroxide solution and 50 ml of 2 mol/L citric acid solution, the agitation was kept until the 3 substances were mixed homogeneously. The resultant reaction precursor solution was transferred into an enclosed reaction vessel with a stirrer and reacted for 6 h under a supercritical condition of 380? C. and 22.3 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The results showed that the crystal structure of the product was similar to that of Example 1.1, indicating complete hexagonal (JCPDS No. 83-1334) tungsten bronze. The morphology and size of the particles were also similar to those of Example 1.1.

Example 1.5

(17) Cesium tungsten bronze was prepared according to the method and steps of Example 1.2, except for the differences as follows:

(18) In the step of neutralizing cesium with acetic acid, acetic acid was changed into nitric acid for neutralization. After the reaction, the slurry was dark blue. The slurry was washed, filtered, dried, and the resultant powder particles were characterized by SEM and XRD. The morphology, crystal structure and size of the particles were similar to those of Example 1.1.

Example 1.6

(19) Cesium tungsten bronze was prepared according to the method and steps of Example 1.2, except for the differences as follows:

(20) In the step of neutralizing cesium with acetic acid, acetic acid was changed into hydrochloric acid for neutralization. After the reaction, the slurry was dark blue. The slurry was washed, filtered, dried, and the resultant powder particles were characterized by SEM and XRD. The morphology, crystal structure and size of the particles were similar to those of Example 1.1.

Example 1.7

(21) 24.99 g of tungstic acid was dissolved in 360 ml of 7 mol/L ammonia solution (the ammonia solution was prepared by mixing 14 mol/L ammonia solution and deionized water in ratio of 1:1), citric acid was added at room temperature and under conditions of vigorous stirring in which the molar ratio of tungstic acid to citric acid was 2, the agitation was kept for 5 h under water-bath heating condition, so as to obtain transparent yellowish sol particles. After the sol particles were filtered and washed, they were added in 300 ml ethanol, and the cesium hydroxide solution which was neutralized by citric acid was added to the suspension of the sol particles and ethanol, in which cesium hydroxide was added in a molar ratio Cs/W of 0.4. The mixed ethanol solution containing the sol particles and cesium was transferred to an enclosed reaction vessel with stirrer and then reacted for 10 h under a supercritical condition of 260? C. and 6.9 Mpa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The morphology and size of the particles were similar to those of Example 1.1. The BET analysis demonstrated the specific surface area of the product was 62.31 m.sup.2/g.

Example 1.8

(22) Cesium tungsten bronze was prepared according to the method and steps of Example 1.7, except for the differences as follows:

(23) Tungsten was directly derived from ammonium tungstate, rather than reaction of tungstic acid and ammonia solution. In the step of dissolving in water, the temperature was elevated from temperature to 80? C. All involved reactants in the high-temperature and high-pressure reaction vessel ware of concentrations identical to those of Example 1.7. After the reaction, a dark blue slurry was washed, filtered, dried, and the resultant powder particles were characterized by SEM and XRD. The crystal structure, morphology and size of the particles were similar to those of Example 1.1.

Example 1.9

(24) 200 ml of 0.5 mol/L NaWO.sub.4 aqueous solution was prepared, and then the solution and 97 ml of 3 mol/L hydrochloric acid solution were mixed and reacted to obtain a light yellow precipitate. The resultant suspension was subjected to liquid-solid separation, and the resultant solid particles were washed with water and ethanol for 3 times respectively. The particles were kept weak acidity, then the washed solid colloid particles were added in 300 ml of ethanol solution and stirred, then 100 ml of ethanol solution which contained 0.2 mol/L cesium carbonate was added under stirring condition, and the agitation was kept for 1 h. Finally, the mixture solution was transferred to an enclosed reaction vessel with a stirrer and reacted for 12 h under a supercritical condition of 280? C. and 7.3 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The crystal structure, morphology and size of the particles were similar to those of Example 1.1. The BET analysis demonstrated the specific surface area of the product was similar to that of Example 1.1.

Example 1.10

(25) Cesium tungsten bronze was prepared according to the method and steps of Example 1.9, except for the differences as follows:

(26) In all steps involving ethanol, ethanol was replaced with iso-propanol. After the reaction, the slurry was dark blue. The slurry was washed, filtered, dried, and the resultant powder particles were characterized by SEM and XRD. The crystal structure, morphology and size of the particles were similar to those of Example 1.1.

Comparison Example 1.1

(27) Cesium tungsten bronze was prepared according to the method and steps of Example 1.4, except for the differences as follows:

(28) In the enclosed reaction vessel, the reaction was performed at 200? C. and 1.5 MPa. XRD analysis results of the particles showed many peaks of impurities besides relatively weak peaks of tetragonal and hexagonal tungsten bronze. SEM was not performed later. The gradually extended reaction time from 6 h resulted in some improvements in crystallization degree of tungsten bronze particles, and hexagonal tungsten bronze with complete crystal structure were obtained when the reaction time was up to more than 2 days. However, the SEM results indicated that the particles were 120-200 nm in width and 600-1000 nm in length. The BET analysis demonstrated the specific surface area of the product was about 33.65 m.sup.2/g.

(29) Through comprehensive consideration of Example 1.1 and Comparison Example 1.1, it was found that the tungsten bronze synthesized under supercritical condition showed unexpected good effects in comparison with conventional hydrothermal or solvothermal methods. The synthetic environment of non-vapor and non-liquid phase under supercritical conditions were favorable for the synthesis of tungsten bronze in which partial reduction was required, besides that, higher solubility of reactants and products under supercritical conditions made the reaction quicker and more complete. By means of adjusting temperature and pressure, the permittivity and density of solvent could be adjusted, the rate and equilibrium of the reaction could be adjusted as well, which makes it possible to control particle size and yield of target product.

Comparison Example 1.2

(30) Cesium tungsten bronze was synthesized using the method and steps of Example 1.6, except for differences as follows:

(31) During the reaction under supercritical conditions, agitation was not performed. The obtained slurry was still dark blue slurry. The powder particles were characterized by SEM and XRD. The crystal structure of the product was similar to that of Example 1.6, but the morphology and size of the product changed, the results were shown in FIG. 3(b), in which particles were not of short rod shape formed under well stirring condition, but irregular shape. It could be seen from the SEM results in FIG. 3(b) that there were all sorts of irregular shape particles with different sizes. The particles could hardly be dispersed because of agglomeration, and a dispersion could hardly be formed by any kinds of subsequent modification and dispersing methods.

(32) The Comparison Example indicated that the mixing state in the process made a great impact on chemical synthesis process. For this reason, vigorous agitation would be essential for all steps involving mixing and reacting during synthesis of precursor and ultimate cesium tungsten bronze particles. This is particularly true for amplification process and industrial production. In the present invention, it was preferential to mix materials by using shear force generated by agitation and shear, and/or to turn the uniform crystallization and crystal transformation of solid particles in liquid into reality, for example, the equipment as mentioned in the international patent applications PCT/SG02/00061 and PCT/CN2010/071651 could be used to realize micromixing in molecular scale.

Example 2

Other Examples for Preparing Alkali Metal Tungsten Bronze Particles

Example 2.1

Example for Preparing Sodium Tungsten Bronze Particles

(33) 200 ml of 0.5 mol/L NaWO.sub.4 aqueous solution was prepared, and then the solution and 97 ml of 3 mol/L hydrochloric acid solution were mixed and reacted to obtain a light yellow precipitate. The resultant suspension was subjected to liquid-solid separation, and the resultant solid particles were washed with water and ethanol for 3 times respectively. The washed solid colloid particles were added in 300 ml of ethanol solution and stirred, then 100 ml of ethanol solution which contained 0.25 mol/L sodium hydroxide was added under stirring condition, an amount of citric acid was used to neutralize sodium hydroxide, and the agitation was kept for 1 h. Finally, the mixture was transferred to an enclosed reaction vessel with a stirrer and reacted for 8 h under a supercritical condition of 270? C. and 7.1 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by SEM and XRD. The XRD results indicated that the structure gave peaks at positions similar to those of JCPDS No. 81-0577. The SEM results showed that the particles were of rod-like or needle-like shape particles. The particles were of 30-50 nm in width and 300-600 nm in length. The EDS results showed that Na/W value was about 0.23 in tungsten bronze.

Example 2.2

Example for Preparing Sodium Tungsten Bronze Particles

(34) A certain amount of 3 mol/L hydrochloric acid was used to regulate 300 ml of 1 mol/L NaWO.sub.4 aqueous solution under vigorous stirring to have a pH value of 1.2. The suspension was filtered, the resultant colloidal particles contained sodium ions and were dispersed in 300 ml of isopropanol. The suspension with isopropanol as solvent was transferred in an enclosed reactor with stirrer and reacted under a supercritical condition of 270? C. and 5.8 Mpa for 8 hours. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by XRD and SEM. The crystal structure, morphology and size of the particles were similar to those of Example 2.1.

Example 2.3

Example for Preparing Sodium Tungsten Bronze Particles

(35) Hydrochloric acid was used to regulate 300 ml of 0.3 mol/L NaWO.sub.4 solution under vigorous stirring to have a pH value of 6.5. Then, 0.5 mol/L NaBH.sub.4 solution was added in the above solution under stirring, and a diluted hydrochloric acid solution was simultaneously added to keep the pH value between 6 and 7. During the addition of NaBH.sub.4 and hydrochloric acid, the solution gradually became dark green, and a precipitate started to generate. After the reaction of the mixture solution was performed for a period of time and the pH value was stable, the suspension stood for a period of time and gradually became brown from dark green. The brown gel in the under layer was washed by water and acetone, and then the gel was dispersed in 200 ml of ethanol. The suspension was transferred in an enclosed reactor with stirrer and reacted under a supercritical condition of 250? C. and 6.7 MPa for 6 hours. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The particles were characterized by XRD and SEM. The crystal structure, morphology and size of the particles were similar to those of Example 2.1. However, the EDS results showed that the Na/W ratio was about 0.28 in the particles.

Example 2.4

Example for Preparing Potassium Tungsten Bronze Particles

(36) Potassium tungsten bronze particles were prepared by using the method and steps of Example 2.1, except for the differences as follows:

(37) Sodium hydroxide solution was replaced with potassium hydroxide, for which the concentration and volume did not change. After the enclosed reaction vessel was cooled, the dark blue slurry was taken out. The slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. o obtain powder particles. The powder particles were characterized by SEM and XRD. The XRD results showed that the crystal structure were well agreed with the standard data (JCPDS 83-1593), and there was not any impurity peak. The powder particles were characterized by SEM and XRD. As a result, the crystal structure, size and morphology of the particles were similar to those of the particles prepared in Example 2.1.

Example 2.5

Example for Preparing Rubidium Tungsten Bronze Particles

(38) 500 ml of 0.15 mol/L WCl.sub.6 ethanol solution was prepared, 100 ml of rubidium chloride ethanol solution was added under stirring in a ratio of Rb:W=0.4, then 100 ml of acetic acid was added, the agitation was kept until the mixture was homogeneous. The dark blue mixture solution was transferred to an enclosed reaction vessel with a stirrer and reacted for 10 h under a supercritical condition of 300? C. and 7.5 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by SEM and XRD. The XRD results indicated that the crystal structure was hexagonal tungsten bronze structure. The SEM images revealed that the particles exhibited rod- or needle-like morphology with width of 40-50 nm and length of 200-300 nm. The EDS showed that the atom ratio of Rb/W was around 0.32. The BET test showed the specific surface area of these particles was 55.54 m.sup.2/g.

Example 3

Example for Preparing Transition Metal-Doped VIB Group Metal Oxide

Example 3.1

(39) 500 ml of 0.15 mol/L WCl.sub.6 ethanol solution was prepared, 100 ml of copper chloride ethanol solution was added under stirring in a ratio of Cu:W=0.3, then 100 ml of acetic acid and trace of water were added, the agitation was kept until the mixture was homogeneous. The dark blue mixture solution was transferred to an enclosed reaction vessel with a stirrer and reacted for 10 h under a supercritical condition of 290? C. and 7.4 MPa. After the enclosed reaction vessel was cooled to room temperature, a blue-green slurry was taken out. The blue-green slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by SEM and XRD. The XRD results indicated that the crystal structure was hexagonal tungsten bronze structure. The SEM images revealed that the particles exhibited rod- or needle-like morphology with width of 40-50 nm and length of 200-300 nm. The EDS showed that the atom ratio of Cu/W was around 0.22. The oxygen element content was slightly lower than 3. The BET test showed the specific surface area of the particles was 35.24 m.sup.2/g.

Example 3.2

(40) 500 ml of 0.15 mol/L sodium tungstate aqueous solution was prepared, hydrochloric acid was used to regulate the solution to have a pH value of about 1.6, to obtain light yellow amorphous particles of tungstic acid. The amorphous particles of tungstic acid and the solution containing ions were separated by centrifugation. Then, the amorphous particles of tungstic acid were homogeneously dispersed in anhydrous ethanol, barium acetate aqueous solution was added under stirring in a ratio of Ba:W=0.3:1, then an amount of acetic acid was added to regulate the pH value of the system, the agitation was kept until the mixture was homogeneous. The mixture solution containing tungsten and barium was transferred to an enclosed reaction vessel with a stirrer and reacted for 10 h under a supercritical condition of 300? C. and 7.3 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The dark blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The results indicated that the crystal structure, morphology and size of the particles were similar to those of Example 1.1. The EDS results showed that the atom ratio of Cu/W was around 0.22. The oxygen element content was slightly lower than 3.

Example 3.3

(41) Tin tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(42) Copper chloride was replaced by tin chloride. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the Sn/W was around 0.24.

Example 3.4

(43) Indium tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(44) Copper chloride was replaced by indium chloride. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the In/W was around 0.22.

Example 3.5

(45) Antimony tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(46) Copper chloride was replaced by antimony chloride. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the Sb/W was around 0.24.

Example 3.6

(47) Zinc tungsten bronze particles were prepared by using the method and steps of Example 3.2, except for the differences as follows:

(48) Barium acetate was replaced by zinc acetate. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 1.1. The EDS showed that the atom ratio of the Zn/W was around 0.24.

Example 3.7

(49) Cerium tungsten bronze particles were prepared by using the method and steps of Example 3.2, except for the differences as follows:

(50) Barium acetate was replaced by cerium nitrate. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 1.1. The EDS showed that the atom ratio of the Ce/W was around 0.24.

Example 3.8

(51) Manganese tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(52) Copper chloride was replaced by manganese chloride. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the Mn/W was around 0.23.

Example 3.9

(53) Titanium tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(54) Copper chloride was replaced by titanium tetrachloride. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the Ti/W was around 0.23.

Example 3.10

(55) Iron tungsten bronze particles were prepared by using the method and steps of Example 3.1, except for the differences as follows:

(56) Copper chloride was replaced by iron chloride. The obtained slurry was of dark orange. After the slurry was dried, the test results of powder particles indicated the crystal structure, size and morphology of the particles were similar to those of Example 3.1. The EDS showed that the atom ratio of the Fe/W was around 0.20.

Example 3.11

(57) 500 ml of 0.2 mol/L WCl.sub.6 ethanol solution was prepared, 100 ml of vanadium pentaoxide ethanol solution was added under stirring in a ratio of V:W=0.2, then 100 ml of acetic acid and trace of water were added, the agitation was kept until the mixture was homogeneous. The dark blue mixture solution was transferred to an enclosed reaction vessel with a stirrer and reacted for 10 h under a supercritical condition of 290? C. and 7.1 MPa. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The dark blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by SEM and XRD. As a result, the crystal structure, size and morphology of the resultant particles were similar to those of Example 3.1. Despite the peaks in the XRD pattern of the particles were analogous to those of hexagonal tungsten bronze, trace structure similar to that of VO.sub.2 seemed to appear. The XPS results indicated the existence of tetravalent vanadium along with pentavalent vanadium. The EDS results showed that the atom ratio of V/W was around 0.16. The color of the powder would be further deepened under the sunlight.

Example 4

Example for Preparing Molybdenum Bronze Particles

(58) Cesium molybdenum bronze particles were prepared using the method and steps of Example 1.2, except for difference as follows.

(59) Sodium tungstate was replaced by sodium molybdate, and the conditions of supercritical reaction were 320? C. and 7.8 MPa. The obtained slurry was of dark blue. After the slurry was dried, the test results of powder indicated the crystal structure, size and morphology of the particles were similar to those of Example 1.2. The EDS results showed that the atom ratio of the Cs/Mo was around 0.29.

Example 5

Example for Preparing Ammonia Tungsten Bronze Particles

(60) 56.6 g of ammonium paratungstate was added into 200 ml of n-propanol under conditions of heating and vigorous stirring to form a semi-dissolved suspension. After cooling, 200 ml of acetic acid was added into the suspension with continuously stirring for a period of time. Then the suspension was transferred into a sealed reactor with stirrer, and reacted under supercritical condition of 290? C. and 7.1 Mpa for 10 h. After the enclosed reaction vessel was cooled to room temperature, a dark blue slurry was taken out. The dark blue slurry was washed, centrifuged to obtain filter cake. The filter cake was vacuum dried at 60? C. to obtain particles in powder form. The particles were characterized by SEM and XRD. The XRD results showed that the crystal structure was substantially in coincidence with that of hexagonal tungsten bronze (JCPDS 42-0452). The SEM revealed that the particles exhibited rod-like morphology with diameter of 30-50 nm and length of 400-500 nm.

Example 6

Hybrid-Doped VIB Group Metal Oxide

Example 6.1

(61) Sodium cesium tungsten bronze particles were prepared by using the method and steps of Example 1.2, except for the differences as follows:

(62) 30% mole percentage of the cesium hydroxide was replaced by sodium hydroxide.

(63) The XRD pattern of the product was similar to that of cesium tungsten bronze. The SEM indicated that the size and morphology of the product were similar to those of Example 1.1. The EDS showed that the atom ratio of Na:Cs:W was around 0.11:0.22:3.

Example 6.2

(64) Sodium cesium tungsten-molybdenum bronze particles were prepared using the method and steps of Example 1.2, except for the difference as follows:

(65) 20% mole percentage of sodium tungstate was replaced by sodium molybdate. 30% mole percentage of cesium hydroxide was replaced by sodium hydroxide.

(66) The XRD spectrum was shown in FIG. 5. The SEM images indicated that the size and morphology of the particles were similar to those of Example 1.2. The EDS test showed that the atom ratio of Na, Cs, W and Mo was around 0.11:0.22:2.4:0.6.

Example 7

Example for Preparing a Dispersion of Tungsten Bronze Particles

Example 7.1

(67) Cesium tungsten bronze nanometer slurry was prepared using the method and steps of Example 1.2 until the filter cake was obtained.

(68) The filter cake was dispersed in 500 ml of methanol, following by addition of 13.8 g of isopropyloxy-tri(ethylenediamino-N-ethoxy) titanate (CAS NO.:65380-84-9) and an appropriate amount of triethanolamine, then modified by an emulsifying machine for 10 minutes under high shear conditions (10000 rpm). The slurry was separated by centrifugation, and then redispersed in 500 ml of ethanol containing a small amount of isopropanol. 6.9 g of isopropyloxy-tri(ethylenediamino-N-ethoxy) titanate was added, and modification was performed by an emulsifying machine under high shear condition (10000 rpm) for 10 minutes. The slurry was separated by centrifugation to obtain modified cesium tungsten bronze particles. The modified particles were dispersed in 500 ml of butyl acetate, vacuum distilled to dry to obtain a dark blue powder. The modified blue powder was redispersed in butyl acetate to have a solid content of 40% (based on weight of the dispersion). The dispersion was tested by dynamic light scattering laser particle size instrument (DLS, LB-550, Horiba), and the results were shown in FIG. 6. As shown in FIG. 6, the average secondary particle size was around 76 nm and D90=123 nm. In the dispersion, the dispersion index of particles was 1.7, and the steepness ratio was 2.74, which indicated that the particles were well dispersed in the dispersion and monodispersion was substantially realized. Further experiments showed that there was no settlement in the dispersion during 20 days, which indicated the dispersion had good stability.

Example 7.2

(69) Sodium cesium tungsten bronze nanometer slurry was prepared using the method and steps of Example 6.1 until the filter cake was obtained. The steps for modification and dispersion of the filter cake were similar to those in Example 7.1. Furthermore, the test results of the dispersion in this example were similar to those of Example 7.1.

Example 7.3

(70) Except for using 2,4-pentanedione as modifying agent, and a small amount of ethanol in butyl acetate as solvent instead, other steps and the amount of modifying agent were similar to those in Example 7.1. Furthermore, the test results of the obtained dispersion were similar to those of Example 7.1.

Example 7.4

(71) Except for using N-(amino-ethyl)-?-aminopropyl trimethoxy silane as modifying agent and ethanol as solvent instead, other steps and amount of modifying agent were similar to those in Example 7.1. Furthermore, the test results of the obtained dispersion were similar to those of Example 7.1.

Comparison Example 7.1

(72) Cesium tungsten bronze particles were prepared by the method and steps of Example 1.2. The steps for modification were similar to those of Example 7.1, except that the powder particles were used for modification and redispersion in the present Comparison Example, while the filter cake was used for modification and redispersion in Example 7.1. It was found in the dispersion procedure that the particles of the powder can hardly be well dispersed to reach a dispersion state similar to that of Example 7.1. It was difficult to achieve nanoscale dispersion for the powder particles even if the amount of modifying agent was increased or the modifying time were extended. In a short period of time, sedimentation appeared in the dispersion. The dispersion was tested by DLS, and the results of DLS were shown in FIG. 6(b). As shown in FIG. 6(b), the average secondary particle size was around 840 nm, and D90 was 1.53 ?m. By Comparing the present Comparison Example with Example 7, it was indicated that hard agglomerates of particles appeared and could hardly be broken and redispersed, and thus did not like soft agglomerates. The hard agglomerates could be redispersed by high-energy redispersion equipments such as ball mills and high-pressure homogenizers. In the present application, tungsten bronze particles were prepared and wet modified without drying process. Furthermore, the particles could be redispersed directly without any high-energy dispersion equipment such as ball mills and high-pressure homogenizers, and the formation of dispersion with good stability and high solid content could be realized.

Example 8

Examples for Applications

Example 8.1

(73) The dispersion prepared in Example 7.2 was diluted by butyl acetate to reach a concentration of 0.5 wt %. The dispersion was tested by UV-Vis/IR spectrometer, and the results were shown in FIG. 7(a). As shown in FIG. 7(a), the visible light transmission of the sample was around 70%, while the infrared rejection was 96%.

Example 8.2

(74) The dispersion prepared in Example 7.4 was diluted by ethanol to reach a concentration of 0.5 wt %. The dispersion was tested by UV-Vis/IR spectrometer. As a result, the visible light transmission of the sample was 70%, and the infrared rejection was 94%.

Example 8.3

(75) The dispersion prepared in Example 7.1 was diluted by butyl acetate to reach a concentration of 0.5 wt %. The dispersion was tested by UV-Vis/IR spectrometer, and the results were shown by curve a in FIG. 7(b); the rubidium tungsten bronze in Example 2.5, the potassium tungsten bronze in Example 2.4 and the sodium tungsten bronze in Example 2.3 were separately redispersed by the method in Example 7.1 and diluted by butyl acetate to reach a concentration of 0.5 wt %, they were all tested by UV-Vis/IR spectrometer, and the results were shown by curves b, c and d, respectively. As a result, all of these samples were obviously functional for short infrared rejection, in which the barrier capabilities of the samples ware in following order: cesium tungsten bronze>rubidium tungsten bronze>potassium tungsten bronze>sodium tungsten bronze.

Example 8.4

(76) The nanometer tungsten bronze (TB) dispersion as prepared in Example 7.1 and the nanometer ZnO butyl acetate dispersion as prepared in PCT/SG2008/000442 were added in BAYER hydroxyl acrylic resin (No. 870, solid content: 70%), so that in the final formula, the mass percentages of acrylic resin, tungsten bronze nanoparticles and ZnO nanoparticles were 25 wt %, 10 wt % and 5 wt %, respectively, and additionally, there were small amounts of flatting agents, antifoaming agents and other adjuvants in the formula.

(77) For comparison, the ATO dispersion as prepared in PCT/CN2013/073210 and the nanometer ZnO butyl acetate dispersion as prepared in PCT/SG2008/000442 were also added in BAYER hydroxyl acrylic resin (No. 870, solid content: 70%), so that in the final formula, the mass percentages of acrylic resin, ATO nanoparticles and ZnO nanoparticles were 25 wt %, 10 wt % and 5 wt %, respectively, additionally, there were small amounts of flatting agents, antifoaming agents and other adjuvants in the formula.

(78) The above two paints were coated on glasses with a roller coating method. The thickness of the paint on the glass was controlled as 40 ?m, which formed a dry film with thickness of 15 ?m. According to Chinese National Standard GB/T 2680-94 (or International standard E 903-96), the glasses coated with paints were tested by UV-Vis/IR spectrometer, and the results were shown in FIG. 8 (a)-(c). In addition, blank PET substrate was tested by UV-Vis/IR spectrometer for comparison. The UV-Vis/IR spectra of the glasses coated with paints in Example 8.4 were shown in FIG. 8, in which FIG. 8(a) showed ultraviolet-visible light-infrared spectrums of blank PET film and ATO coated PET film, FIG. 8(b) showed ultraviolet-visible light spectrums of ATO coated PET film and TB painting coated PET film, and FIG. 8(c) showed ultraviolet-visible light-infrared spectrum of ATO coated PET film and tungsten bronze (TB) painting coated PET film.

(79) As shown in the Figures, the paints containing ZnO nanoparticles along with ATO or tungsten bronze nanoparticles had good functions of blocking ultraviolet and infrared, and their sunlight control performances were shown in Table 2, as follows.

(80) Table 2: The sunlight control performances of glasses coated with different types of paints

(81) TABLE-US-00002 TABLE 2 Ultraviolet Visible light Infrared Glasses coated with rejection transmittance rejection different types of paints (350 nm) (%) (550 nm) (%) (%) Blank PET film 2% 99% 1% ATO + ZnO, roller coating 98% 82% 79% method TB + ZnO, roller coating 99% 78% 94% method

(82) The present invention is described by illustrations with the above examples. However, it should be understood that these examples are not to limit the present invention. Ordinary technicians can undertake various modifications or changes to the present invention, which all fall within the protection scope of the present invention.