TWI440695B - Preparation of Manganese Activated Zinc - Aluminum Spinel Green Fluorescent Nanometer Powder by Sol - Gel Technique and Its - Google Patents

Description

Preparation of manganese activated zinc aluminum spinel green light fluorescent nanometer powder by sol gel technique and method thereof

The invention relates to a method for preparing manganese activated zinc aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) green fluorescent nanometer powder by sol gel technique, in particular by controlling zinc chloride and aluminum Hydrolysis and degumming reaction of propanolate, and doping different concentrations of manganese as activator to form a clear sol, polycondensation, gelation, drying and heat treatment to prepare homogeneous single-phase zinc-aluminum spinel fluorite nanopowder By adjusting the doping concentration and changing the heat treatment temperature and atmosphere, a manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) nanopowder having high efficiency of emitting green light fluorescence can be obtained.

In recent years, the issues of energy and environmental protection have been highly valued. The international community is actively developing new energy supply technologies and green materials. The development of low-pollution and high-efficiency fluorescent materials has become one of the most urgent issues today. Fluorescent materials have the advantages of low power consumption, long life, no heat radiation and good reaction speed. Their applications include fluorescent lamps, neon lights, light-emitting diodes and other lighting devices, as well as key components of the current high-profile displays. In the 1990s, Japan first developed blue-emitting LEDs with commercial applications such as gallium nitride, and used yellow fluorescent yttrium aluminum garnet (YAG) as a high-efficiency white light source to develop new fluorescent materials for lighting equipment. It is a major direction for active research in the industry and academia.

Zinc-aluminum spinel (ZnAl ₂ O ₄ ) has a high melting point (about 1980 ° C), low dielectric constant (about 10), acid and alkali resistance, hydrophobicity and high mechanical strength. It is a typical spinel (spinel). The structure of oxide ceramics is mainly used in the catalytic reaction or catalyst carrier of the catalyst. Since ZnAl ₂ O ₄ has a direct wide energy gap [Eg=3.8 electron volts (eV)], the wavelength is less than 320 nm. The light wave of the meter (nm) has a good barrier effect and can be applied to the anti-ultraviolet optical coating of the space shuttle (as disclosed in U.S. Patent Nos. 5,143,888 and 5,807,909 to Olbrich et al.). Recent literature studies have shown that ZnAl ₂ O ₄ powder doped with rare earth elements has good luminescence properties and can be applied to solid laser materials, fluorescent materials, and full color displays (such as Zawadzki et al. in the Journal of Alloys and Compound 323-324 (2001), 279-282 ).

Traditionally, ZnAl ₂ O ₄ fluorescent powders are mainly produced by solid state reaction. It is known to prepare ZnAl ₂ O ₄ fluorescent powder by solid state reaction, which has mechano-luminescence and thermoluminescence. Features that can be applied to photosensors and stress imaging components (as disclosed by Matsui et al., Applied Physics Letters 78 (2001), 1068-1070 and Physical Review B69 (2004), 235109 ), but solid state reactions are diffusion dependent processes. It needs to be treated with high temperature (about 1200 °C) for a long time, which is basically a high-cost energy-consuming process, which is easy to cause powder coarsening (particle size larger than micrometer scale), segregation of zinc oxide (ZnO) and α-Al ₂ O ₃ crystallization. The phase, the non-homogeneous distribution of the activator, and the low purity make it impossible to obtain reliable luminescence intensity.

In addition, the current research and development technology has developed a sol-gel method to prepare cobalt-doped zinc-aluminum spinel (ZnAl ₂ O ₄ : 1% Co ²⁺ ) phosphor powder (such as Duan et al. in J. Alloys and Compounds, 386 (2005), 311-314 ), a phosphor powder prepared by using zinc nitrate and aluminum nitrate as precursors, the phosphor powder having red-green light [650 to 530 nm (nm)] Radiation characteristics, but the preparation of the phosphor powder by the sol-gel method still has the following disadvantages: since the nitrate contains a large amount of crystal water, the process is difficult to control, and it is necessary to add a large amount of high-concentration citric acid solution or gelatin as gelation. This tends to cause the powder to reduce the radiation intensity by leaving an excessive amount of functional groups such as OH.

It is known that the preparation of ceramic powder by sol-gel technique has the advantages of high homogeneity, nano crystal form, low temperature process, and low equipment cost, and the process conditions such as precursor and solution concentration are known to strongly affect the sol-gel state. Further, it affects the homogeneity and characteristics of the colloidal product in the future (as disclosed by the inventor of the Republic of China Patent No. 274048). Especially for multi-component materials, different precursors have significant differences in hydrolysis and polycondensation rates, which tend to cause segregation of the second phase of the colloid during crystallization; in other words, the aforementioned sol-gel technique Preparation of zinc-aluminum spinel (ZnAl ₂ O ₄ ) phosphor powder, there are still many limitations and shortcomings. If a suitable precursor can be selected, a clear and transparent sol can be prepared by hydrolysis and degumming reaction to make the colloidal particles. The molecule is uniformly suspended and dispersed, and the (ZnAl ₂ O ₄ ) fluorescent powder can be directly prepared by polycondensation reaction without adding any gelling agent, so that the powder has a single-phase homogeneous structure, and the powder can be formed into a powder. The characteristics of the rice crystal type and the nanometer particle size have been developed. The method for preparing the ZnAl ₂ O ₄ :Mn ²⁺ phosphor powder by the sol-gel method has a profound significance in application and is of great significance in application. Compared with the conventional solid-state reaction technology, the sol-gel method has another advantage of preparing ZnAl ₂ O ₄ :Mn ²⁺ fluorescent powder, and has the potential of low-temperature mass production of nano-powder, and the device is relatively simple. Can significantly reduce manufacturing costs.

So far, there has not been any domestic and foreign research on the mixed metal alkoxide and metal chloride salt, directly hydrolyzed, degummed, and polycondensed, without adding any gelling agent, and prepared by a different heat treatment process to have a homogeneous single phase. The sol-gel technique of high-luminous intensity manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) fluorescent nano-powder is proposed.

In summary, the present invention provides a method for preparing a manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) green fluorescent nano-powder by a sol gel technique to solve the above problems.

The object of the present invention is to provide a method for preparing manganese activated zinc aluminum spinel green fluorescent nanometer powder by sol gel technique, by using a sol-gel technique, by controlling metal chloride salt and metal alkoxide Hydrolysis and degumming reaction, without adding any gelling agent, doping manganese as an activator, preparing zinc-alumina spinel fluorescent nano-powder by condensation polymerization, gelation, drying and heat treatment, and adjusting the doping amount and The heat treatment conditions are changed to control the green light emission intensity.

A second object of the present invention is to provide a lyotropic gel process capable of producing homogenization, nanocrystal form, nanometer particle size, and narrow particle size distribution to prepare a homogeneous single-phase manganese-activated zinc-aluminum spinel ( ZnAl ₂ O ₄ :Mn ²⁺ ) High-efficiency green fluorescent nano-nano powder.

Another object of the present invention is to provide a manganese activated zinc-aluminum spinel having high purity, nanostructure, high homogeneity, high efficiency green light intensity, low cost, simple equipment, and reduced process temperature. ZnAl ₂ O ₄ :Mn ²⁺ ) fluorescent nano-powder.

A method for preparing a manganese-activated bismuth-zinc-aluminum spinel green fluorescent nano-nano powder by a sol-gel technique, which comprises the steps of: preparing a transparent sol: separately measuring chlorine according to a stoichiometric ratio Zinc [ZnCl ₂ ] has a mass of 1 to 1.5 g and aluminum isopropoxide [Al(OC ₃ H ₇ ) ⁱ ₃ ] has a mass of 3.8 to 4.5 g, both of which are dissolved in an alcohol solvent and stirred and reacted. At the same time, a solution containing manganese ions is added to carry out the reaction, and the concentration of the manganese ions is between 0.2 and 10.0 mol%, and reacts at a reaction temperature to form a mixed solution; then, the mixed solution is added to water and hydrochloric acid. The solution is subjected to hydrolysis and degumming reaction under a reaction condition to form a uniformly dispersed colloidal molecular suspension, and the suspension after the hydrolysis reaction is allowed to stand at 20 ° C to 30 ° C for a period of time to prepare the transparent sol; The step of preparing a zinc aluminum spinel fluorescent nanometer powder: performing a polycondensation reaction under the polymerization reaction condition of the transparent sol according to the above step to obtain a transparent gel, and the gel is dried at a temperature of 80 to Between 200 ° C, dry Drying and refining into a colloidal powder; then, the colloidal powder is calcined, the calcination temperature is between 600 and 1000 ° C, and the homogenization single phase is obtained between 2 and 10 hours of calcination time. zinc-aluminum spinel (ZnAl ₂ O ₄₎ powder nm fluorescence.

Preferably, the method comprises the steps of preparing the transparent sol, and the zinc chloride (ZnCl ₂ ) having a mass of about 1.39 g and the aluminum isopropoxide [Al(OC ₃ H ₇ ) ^{i having a} mass of about 4.17 g; ₃ ], while dissolving methanol or ethanol at a concentration between 0.3 and 0.5 mol/l.

Preferably, the method comprises the steps of preparing a transparent sol, wherein the water concentration is between 0.5 and 2.0 m/l and the concentration of the hydrochloric acid solution is between 0.1 and 0.3 m/l. The reaction conditions have a temperature of 25 ° C and a time between 0.5 and 2 hours.

Preferably, the method comprises the step of preparing the nano powder, the polycondensation reaction condition is 25 ° C and the relative humidity is 55 to 80%, and the drying temperature is 80 ° C to 200 °C.

Preferably, the method comprises the step of preparing the nano powder, wherein the concentration of the manganese ion is 0.2 to 10.0 mol%, the calcination temperature is 1000 ° C, and the heating rate is about 10 ° C / Minutes, and the calcination time is 2 to 10 hours.

Preferably, the method wherein the colloidal powder is calcined and calcined in an air furnace or a N ₂ -H ₂ reducing atmosphere.

The present invention provides a zinc aluminum spinel green light fluorescent nanometer powder which is produced by the above method.

Preferably, the zinc-aluminum spinel green fluorescent nano-nano powder has an average grain size of between 12 and 20 nanometers (nm) after heat treatment at 600 to 1000 ° C.

Preferably, the zinc aluminum spinel green fluorescent nanometer powder has a particle size of between 20 and 25 nanometers (nm) after heat treatment at 1000 ° C.

Preferably, the zinc aluminum spinel green fluorescent nanometer powder has an excitation light wavelength of about 460 nanometers (nm) and an emission wavelength of about 512 nanometers (nm), wherein the manganese ions are doped. The concentration was 3.0 mol%, and the calcination time was 1000 ° C in a reducing atmosphere, and the calcination time was 10 hours, which had the best luminescence intensity.

The phosphor powder obtained by the above method has an average grain size of 12 to 20 nanometers (nm) after calcination heat treatment at 600 to 1000 ° C, wherein there is no significant weight loss after heat treatment at 800 ° C. After heat treatment at 1000 ° C, the powder has a particle size of 20 to 25 nanometers (nm), and the powder has a nearly spherical appearance and a narrow particle size distribution. The fluorescence spectrum shows that when the manganese ion doping concentration is between 0.2 and 10.0 mol%, and the wavelength is 460 nm (blue) excitation, it has the characteristic of emitting high-efficiency green light, and the emission peak wavelength is 512 nm. (nm), wherein the manganese ion doping concentration is 3.0 mol%, which has the best luminescence intensity, and is sintered at 1000 ° C in a reducing atmosphere, and has a maximum luminescence intensity when the calcination time is 10 hours.

The invention provides a sol-gel technique for preparing a manganese-activated zinc-aluminum spinel fluorescein nanometer powder and a method thereof, and the above advantages have the following advantages:

1. The operation step of the invention is easy and does not need to add any gelling agent, and only needs to control the hydrolysis and degumming reaction by the low water amount and the hydrochloric acid electrolyte, so that the colloidal molecules can be uniformly suspended and dispersed, and can be directly prepared by polycondensation polymerization. Manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ : Mn ²⁺ ) phosphor powder can significantly improve the purity, and can also synthesize a homogeneous single-phase zinc-aluminum spinel structure at a low temperature, which has significant effects on energy conservation.

2. The manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) nano-fluorescent powder has high homogeneity, nano crystal form and nanometer particle size, and prepares the powder The equipment required for the body is simple and can effectively reduce the cost.

3. The manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ : Mn ²⁺ ) nano-fluorescent powder has high-efficiency emission green light characteristics, and can adjust the concentration of activator (manganese ion) and The heat treatment conditions control the luminous intensity, and can be widely applied to various types of lighting equipment, display components, light sensors, instrument panels of automobile locomotives, warning lights and traffic signs.

4. The manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) nano-fluorescent powder has a nanometer and narrow particle size distribution, and has a thin film thickness in optical coating application. It increases density and significantly improves luminous efficiency. It is suitable for display components in various fields such as cathode ray tube (CRT), plasma display (PDP), field emission display (FED) and electroluminescence.

5. The sol-gel method used in the present invention can also be applied to the preparation of a zinc-aluminum spinel film, which contributes to the development of this material for future large-area full-color displays, field emission displays, white LEDs and lighting equipment.

6. The manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) nano green fluorescent powder of the invention can be applied to white LEDs and effectively improve the unnatural problem of current white LED illumination, and has Low power consumption, long life and good reaction speed.

7. The sol-gel technique used in the present invention can synthesize a homogeneous single-phase zinc-aluminum spinel nano-powder at a low temperature by controlling hydrolysis and gelation reaction and doping manganese ions as an activator, and adjusting and mixing The heterogeneous concentration and changing the heat treatment conditions control the intensity of the green light emission. Compared with other conventional processes, it has many advantages such as high purity, nano crystal form and particle size, high homogeneity, high efficiency green light intensity, low cost, simple equipment, and reduced process temperature. Can be widely used in lighting equipment, light-emitting diodes, display light-emitting elements, photoluminescent elements, electroluminescent elements, cathode ray tubes (CRT), plasma display (PDP), field emission display (FED), biomedical Various fields such as detectors, laser semiconductors, transparent conductive materials, laser semiconductors, and the medical industry, as well as various fields such as the medical industry.

In summary, this case is not only innovative in low-temperature synthesis of single-phase zinc-aluminum spinel fluorescing powder and its nano-type, but also can enhance the above-mentioned multiple functions compared with conventional articles, and should fully meet the novelty and progressiveness. The statutory invention patent requirements, 提出 apply in accordance with the law, I ask you to approve the invention patent application, in order to invent invention, to the sense of virtue.

In order to understand the technical features and practical effects of the present invention in detail, and in accordance with the contents of the specification, further detailed embodiments as shown in FIGS. 1 to 7 are as follows:

Example

Referring to FIG. 1 , a method for preparing a manganese-activated zinc-aluminum spinel fluorescein nano-powder by a sol-gel technique is provided. The manufacturing process is as follows: First, a step of preparing a transparent sol: respectively taking a mass of about 1.39 g. Zinc chloride (ZnCl ₂ ) and aluminum isopropoxide [Al(OC ₃ H ₇ )i ₃ ] having a mass of about 4.17 g are dissolved in a methanol or ethanol solvent and stirred for 1 hour, and the alcohol solvent concentration is 0.4 mol/liter. The reaction is carried out at a temperature of 25 ° C, and doping treatment is carried out by adding manganese chloride (MnCl ₂ ) to form a mixed solution, and the concentration of manganese ions (Mn ²⁺ ) in the mixed solution is between 0.2 and 10.0 mol%. Then, the mixed solution is placed in a constant temperature water bath at 25 ° C for reflux condensation, and water and hydrochloric acid solution are added for hydrolysis and degumming reaction, so that the colloidal molecules are uniformly suspended and dispersed, and the reaction time is between 0.5 and 2 hours. The reaction temperature is 25 ° C, the water concentration is between 0.5 and 2.0 m / liter, and the concentration of hydrochloric acid is between 0.1 and 0.3 m / liter; the suspension after the hydrolysis reaction is allowed to stand at room temperature Set aside for a period of time to produce a clear transparent sol.

The step of preparing a zinc aluminum spinel fluorescent nanometer powder: the transparent sol obtained by the above method is subjected to polycondensation polymerization at 25 ° C and a relative humidity of 55% to obtain a transparent gel; the gel is passed through 80 ° C Drying and refining into a colloidal powder, and then placing the powder in a crucible in an air furnace or a N ₂ -H ₂ reducing atmosphere for a calcining process, setting the calcining heat treatment temperature to be between 600 and 1000 ° C, and heating rate At 10 ° C / min, the calcination time is between 2 and 10 hours. After the calcination is completed and the furnace is cooled to room temperature, a homogeneous single-phase manganese-activated zinc-aluminum spinel (ZnAl ₂ O ₄ : Mn ^{2+ ) can be obtained.} Powder; by controlling the calcining temperature and time of the calcining process, the homogeneous single-phase zinc-aluminum spinel structure can be obtained, and the appropriate calcination temperature and time can increase the crystallinity of the powder.

As shown in FIG. 2, after the manganese activated zinc-aluminum spinel (ZnAl ₂ O ₄ :Mn ²⁺ ) fluorescent nano-powder prepared by the above steps is subjected to a heat treatment, the calcination temperature is between 600 and 1000. Between ° C, the average grain size of the fluorescent nanopowder is between 12 and 20 nanometers (nm).

As shown in FIG. 3, the fluorescent nano-powder (ZnAl ₂ O ₄ ) has a main weight loss between 30 and 120 ° C and between 200 and 700 ° C after heat treatment, and is not obvious after heat treatment at 800 ° C. Weight loss; after heat treatment at 1000 ° C, the particle size of the fluorescent nano-nanoparticle is between 20 and 25 nanometers (nm), as shown in Figure 4, different manganese ion concentration is doped to the zinc-aluminum spinel In the powder, wherein FIG. 4(a) Mn ²⁺ = 3.0 mol% and FIG. 4(b) Mn ²⁺ = 6.0 mol%, the powder shown has a nearly spherical appearance and a narrow particle size distribution. Manganese doping concentration and heat treatment atmosphere have no significant effect on crystallinity, thermogravimetric loss, grain size, and particle size. However, when the manganese ion doping concentration is higher than 5.0 mol%, the agglomeration state of the powder is slightly increased. And the manganese ion doping concentration significantly affects the luminescence intensity.

As shown in FIG. 5, the fluorescence spectrum of the manganese-activated zinc-aluminum spinel powder after calcination at 1000 ° C shows that when the manganese ion doping concentration is between 0.2 and 10.0 mol%, the heat treatment temperature is 800. After 1000 ° C, after excitation at a wavelength of about 460 nm blue light (λ _ex = 460 nm), it has a green emission characteristic with an emission peak wavelength of about 512 nm (λ _em = 512 nm), which is attributed to free electrons in the activator Mn ^{+ 2} ion. ⁴ T ₁ → ⁶ A ₁ energy step migration, wherein the manganese ion doping concentration of 3.0 mol% has the best luminous intensity, as shown in Figure 5 and Figure 6, and the reduced atmosphere is 1000 ° C The calcination time is 10 hours and has the best luminous intensity, as shown in Fig. 7.

Figure 1 is a flow chart of the preparation of a specific embodiment of the present invention.

2 is an X-ray diffraction diagram of a powder after calcination at 1000 ° C according to a specific embodiment of the present invention.

Figure 3 is a thermogravimetric analysis curve of a powder after drying according to a specific embodiment of the present invention.

4 is a micrograph of a specific embodiment (a) Mn ²⁺ = 3.0 mol % and (b) Mn ²⁺ = 6.0 mol% of manganese activated zinc aluminum spinel powder after 1000 ° C simmering .

Fig. 5 is a fluorescence emission spectrum of a manganese-activated zinc-aluminum spinel powder after calcination at 1000 ° C according to a specific embodiment of the present invention.

Figure 6 is a graph showing the relationship between the luminescence intensity of manganese-activated zinc-aluminum spinel and the doping concentration of manganese ions (Mn ²⁺ ) according to a specific embodiment of the present invention.

Figure 7 is a graph showing the relationship between the luminescence intensity of manganese activated zinc-aluminum spinel and heat treatment conditions according to a specific embodiment of the present invention.

Claims (10)

A method for preparing manganese activated strontium zinc aluminum spinel green light fluorescent nanometer powder by sol-gel technique, comprising the steps of: preparing a transparent sol: respectively taking chlorination with a mass between 1 and 1.5 g Zinc (ZnCl ₂ ) and aluminum isopropoxide [Al(OC ₃ H ₇ ) ⁱ ₃ ] with a mass between 3.8 and 4.5 g, both of which are dissolved in an alcohol solvent and stirred and reacted while adding a The manganese ion solution is reacted, and the manganese ion concentration is between 0.2 and 10.0 mol%, and reacted at a reaction temperature to form a mixed solution; then, the mixed solution is added to water and hydrochloric acid solution under a reaction condition The hydrolysis and degumming reaction are carried out to form a uniformly dispersed colloidal molecular suspension, and the suspension after the hydrolysis reaction is allowed to stand at 20 ° C to 30 ° C for a period of time to prepare the transparent sol; and a zinc aluminum spinel is prepared. Step of fluorescein nano-powder powder: the transparent sol according to the above step is subjected to polycondensation under a polymerization reaction condition to obtain a transparent gel, and the gel is dried at a temperature between 80 and 200 ° C, and dried. And refined into a colloidal powder; Then, the colloidal powder is calcined, the calcination temperature is between 600 and 1000 ° C, and the calcination time is between 2 and 10 hours, and a homogeneous single-phase zinc-aluminum spinel (ZnAl ₂ O is obtained). ₄ ) Fluorescent nano-powder. The method of claim 1, wherein the step of preparing the transparent sol comprises a zinc chloride (ZnCl ₂ ) having a mass of about 1.39 g and an aluminum isopropoxide having a mass of about 4.17 g [Al (OC). ₃ H ₇ ) ⁱ ₃ ], while being dissolved in methanol or ethanol at a concentration between 0.3 and 0.5 mol/l. The method of preparing the transparent sol according to the method of claim 1, wherein the water concentration is between 0.5 and 2.0 m/l and the concentration of the hydrochloric acid solution is between 0.1 and 0.3 m/l. The manganese ion concentration is between 0.2 and 10.0 mol%, and the reaction conditions have a temperature of about 25 ° C and a time between 0.5 and 2 hours. The method of preparing the nano-powder according to the method of claim 1, wherein the polycondensation reaction condition is carried out at about 25 ° C and a relative humidity of 55 to 80%, and the drying temperature is 80 ° C. Up to 200 ° C. The method of claim 1, wherein the manganese ion concentration is 0.2 to 10.0 mol%, the calcination temperature is 1000 ° C, the heating rate is 10 ° C / min, and the calcination time is Simmer for 2 to 10 hours. The application method of claim 1 patentable scope clause, wherein the colloidal powder calcination furnace may be air or N ₂ -H ₂ reducing atmosphere. A zinc-aluminum spinel green-light fluorescent nano-powder, which is produced by a method according to any one of claims 1 to 6. The zinc-aluminum spinel green fluorescent nano-nano powder described in claim 7 is characterized in that the average grain size of the nano-powder is between 12 and 20 nanometers (nm) after the heat treatment is 600 to 1000 ° C. between. The zinc-aluminum spinel green fluorescent nano-nano powder described in claim 7 is characterized in that the nano-powder has a particle size of between 20 and 25 nanometers (nm) after the heat treatment at 1000 °C. The zinc-aluminum spinel green fluorescent nano-nano powder according to any one of claims 7 to 9, wherein the nano-powder has an excitation light wavelength of about 460 nm (nm) and an emission wavelength of about 512. Nano (nm), in which the manganese ion doping concentration is 3.0 mol%, and the calcination time is 1000 ° C in a reducing atmosphere, and the calcination time is 10 hours, which has the best luminescence intensity.