JP4949546B2 - Blue-emitting and visible-emitting sol-gel glass - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a melting method that requires melting of raw materials at a high temperature during glass production, blue light emission from divalent europium ions (Eu ²⁺ ) or the like without requiring heat treatment in a reduction furnace after glass production. The present invention relates to a sol-gel glass that produces visible light emission based on the above.
[0002]
[Prior art]
Ceramics or glass to which rare earth elements are added have already been put into practical use, and lamp phosphors, cathode ray tube phosphors, long persistence phosphorescent materials, and the like are well known.
These are generally opaque base materials obtained by adding terbium (Tb) or europium (Eu), and terbium (Tb) emits strong light in the most sensitive green region, while europium ( Eu) is used as a fluorescent material according to the application because it exhibits fluorescence in the red light emitting region.
[0003]
Further, those using a transparent body as a base, that is, using transparent glass, are disclosed in JP-B-57-27047, JP-B-57-27048, JP-A-8-133780, JP-A-10-167755, etc. Molten glass is used as the base glass. Currently, borosilicate glass, fluorophosphate glass, aluminate glass, or the like having a relatively low melting temperature is used as the base glass.
As a specific production method, raw materials are prepared in a predetermined weight ratio with silicon (SiO ₂ ), 5 to 50 mol%, and boric acid (B ₂ O ₃ ) 10 to 55 mol% as a main composition. Stable glass is obtained by melting at a temperature of 1,200 to 1,500 ° C. for 2 to 3 hours, pouring into a mold and molding.
In the case of fluorophosphate glass, a raw material mainly composed of aluminum phosphate 3 to 5%, barium phosphate 3 to 5%, aluminum fluoride 20 to 35% and calcium fluoride 22 to 28% is used at a predetermined weight ratio. As an industrial product, the prepared raw material is melted at 900 to 1,300 ° C., poured into a graphite mold and molded, or in some cases, melting in a reducing atmosphere or an inert atmosphere described below is required. It was also a method with poor mass productivity.
[0004]
Further, as a means for lowering the glass melting temperature, several percent of oxides such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), zinc (Zn) are added to the fluorophosphate glass. It is devised to obtain industrially inexpensive products, such as improving the meltability of glass by reducing the melting temperature by adding elements such as lithium (Li), sodium (Na), potassium (K), etc. ing.
Furthermore, in molten glass to which europium has been added, europium (Eu) ions are usually stable trivalent ions (Eu ³⁺ ), which mainly emit red light, and are further heat treated in a reducing atmosphere. It is known that blue light emission can be obtained by changing from trivalent to divalent europium ion (Eu ²⁺ ). Therefore, when trying to obtain blue light emission, it is difficult to install and manage a reduction furnace in which the melting temperature of the base glass used conventionally is around 1,000 ° C. and industrially exceeds 600 ° C., The problem was that it took considerable cost to maintain the reducing atmosphere.
[0005]
As a means of avoiding the above-described method of undergoing an industrially high temperature process, J.A. of Luminescence, 78, p63, '98 and Europium (Eu) ions in silicate-gel silicate glass using chlorinated raw materials as disclosed in J. Appl. Phys, 81 (9), p12, '97 There was also a report that blue light emission and yellow red light emission were obtained in a single glass or a fluorescent glass co-doped with samarium (Sm) ions and aluminum (Al) ions.
[0006]
In addition, J.H. of Non-Crystalline Solids, p197, '96 has also been reported to emit blue light by co-addition of europium (Eu) ions and aluminum (Al) ions, but the light emission intensity is weak and is useful for practical use. It wasn't.
In a blue light emitting glass containing divalent europium ions (Eu ²⁺ ), as a method of increasing the blue light emission intensity, the relationship with the amount of chlorine added, the amount of europium (Eu) added within the range where no concentration disappears, Although the addition of a plurality of rare earth ions including europium (Eu) ions has been disclosed, reduction heat treatment after glass production is also possible in the sol-gel method capable of producing glass at a low temperature, which is industrially advantageous over the melting method. The present situation is that no divalent europium ion (Eu ²⁺ ) is produced without producing a glass that emits blue light with high emission intensity.
[0007]
[Problems to be solved by the invention]
The object of the present invention is to solve the problem of high cost associated with high-temperature reduction furnace treatment, easier to manufacture in the low-temperature process, and by combining with various ions, organic molecules, etc. for the low-temperature process. It is an object to provide a blue light emitting sol-gel glass having a high light emission intensity by a sol-gel method which can be easily enhanced in function and a visible light emitting sol-gel glass based thereon.
[0008]
[Means for Solving the Problems]
In the present invention, a sol-gel reaction is performed using a starting solution containing europium (Eu), which is a luminescent matrix, and a reducing agent R (any one of Al, Zn, Ca, Mg) in addition to a raw material for forming a glass matrix. Wake up. In this sol-gel reaction, the reducing agent gives itself or oxygen electrons to europium ions, and thus has a function of changing trivalent europium ions (Eu ³⁺ ) to divalent (Eu ²⁺ ). (Reducing ability) And since the divalent europium ion (Eu ²⁺ ) emits blue light by ultraviolet light excitation, it is possible to obtain a blue light emitting glass in which the glass matrix emits blue light by ultraviolet light irradiation. became.
[0009]
On the other hand, the conventional technology for molten glass that has already been put into practical use is not a melting method that requires a high temperature, but a low-temperature sol-gel method. The difference is that a divalent europium ion (Eu ²⁺ ) that contributes to blue light emission is produced during the production. Since the present invention can be easily produced at a lower temperature, it is an industrially excellent means. In addition, other luminescent ions and molecules including organic molecules can be co-added without thermal decomposition or modification, thus enabling higher functionality and complexing.
[0010]
[Action]
Usually, the starting material of sol-gel glass is Si raw material such as tetraethoxysilane Si (OC ₂ H ₅ ) ₄ , H ₂ O for hydrolysis, solvent (alcohol such as C ₂ H ₅ OH), acid as catalyst (Hydrochloric acid, sulfuric acid, nitric acid, etc.) or ammonia and other additives. When europium (Eu) is used as an additive, Eu becomes stable as a trivalent ion (Eu ³⁺ ), and an Eu ³⁺ added sol-gel glass that generates red light emission from Eu ³⁺ by ultraviolet light excitation is obtained. In contrast, when an appropriate amount of at least europium (Eu) and a reducing agent R (any one of Al, Zn, Ca, and Mg) are included as starting materials, the solution of the reducing agent R is formed along with the hydrolysis of the solution and the formation of glass by firing. Divalent Eu ions (Eu ²⁺ ) are obtained by the reducing ability.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
When producing sol-gel glass using tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ), europium nitrate (Eu (NO ₃ ) ₃ .6H ₂ O) as a raw material, aluminum butoxide (Al (OC ₄ H ₉ ) ₃ ) or aluminum nitrate _{(Al (NO 3) 3 ·} 9H 2 O), the finished component of the sol-gel glass SiO _2: Al ₂ O _3: when expressed in mol% in terms of Eu ₂ O _3, Eu is Eu ₂ O ₃ in terms of And 5 mol% or less, and Al is added so as to be 10 mol% or less in terms of Al ₂ O ₃ . The raw material is dissolved in ethanol, water and nitric acid solution to obtain a starting sol. In this state, a gelation reaction is caused by a normal sol-gel process, and when heated to about 800 ° C. to produce a sol-gel glass, europium ions, which are usually trivalent, become divalent due to the reducing ability of the aluminum, thereby A sol-gel glass emitting blue light is obtained. This starting material molecule is an example and does not limit the scope of the present invention.
[0012]
FIG. 1 shows the dependence of the emission spectrum on the Eu concentration. The horizontal axis represents wavelength (nm), and the vertical axis represents the emission intensity (arbitrary unit). When the Eu concentration is 0.35 mol%, the emission near the wavelength of 400 nm shows a peak, and when the Eu concentration is 1.41 mol%, the emission near the wavelength of 620 nm shows a peak.
[0013]
FIG. 2 shows the dependence of the emission spectrum on the Al concentration. The horizontal axis represents wavelength (nm), and the vertical axis represents the emission intensity (arbitrary unit). When the Al concentration is 0.82 mol%, the emission near the wavelength of 420 nm shows a peak, and when the Al concentration is 19.8 mol%, the emission near the wavelength of 620 nm shows a peak.
[0014]
[Example 2]
In the method of Example 1 of the present invention (described in claims), a blue light-emitting sol-gel glass having an arbitrary shape was obtained by potting a sol-gel glass raw material using a container having an arbitrary shape as a mold.
[0015]
[Example 3]
In the method of Example 1 of the present invention (described in claims), a blue light-emitting thin-film sol-gel glass could be obtained by dip coating or spin coating on a glass or other substrate.
[0016]
[Reference Example 1]
In the method of Example 1 of the present invention (described in the claims), a sol-gel glass containing a divalent europium ion (Eu ²⁺ ) and another luminescent matrix is prepared and irradiated with ultraviolet light, whereby 2 for ultraviolet light excitation. A sol-gel glass using visible light emission other than blue was obtained by mixing the blue light emission from the valent europium ion (Eu ²⁺ ) and the light emission from the other light-emitting matrix.
[0017]
[Reference Example 2]
In the method of Example 1 of the present invention (described in claims), a sol-gel glass containing a divalent europium ion (Eu ²⁺ ) and another luminescent matrix is prepared and irradiated with ultraviolet light, thereby divalent to ultraviolet light excitation. The other luminescent matrix is excited by blue emission from the europium ion (Eu ²⁺ ), or the other luminescent matrix is electronically excited through the Eu ²⁺ level, Alternatively, it was possible to obtain a sol-gel glass using a mixed color light emission of blue light emission from Eu ²⁺ and light emission from another light emitting matrix.
[0018]
By using a substance containing Al such as aluminum nitrate (Al (NO ₃ ) ₃ .9H ₂ O), aluminum butoxide (Al (OH ₄ H ₉ ) ₃ ) as a reducing agent, the final component of the sol-gel glass is SiO ₂ : When expressed in terms of mol% of Al ₂ O ₃ : Eu ₂ O ₃ , it is determined by Eu ²⁺ in a region where Eu is 5 mol% or less in terms of Eu ₂ O ₃ and Al is 10 mol% or less in terms of Al ₂ O _3. Blue light emission, particularly blue light emission by Eu ²⁺ is observed remarkably in a region where Eu is 2 mol% or less in terms of Eu ₂ O ₃ and Al is 5 mol% or less in terms of Al ₂ O ₃ .
[0019]
【Effect of the invention】
As described above, the visible light-emitting sol-gel glass according to the present invention solves the problem of high cost associated with high-temperature reduction furnace processing at the time of production, and is easier to produce in a low-temperature process, and for a low-temperature process. There are advantages such as having a high emission intensity by a sol-gel method that is easy to achieve high functionality by combining with various ions and organic molecules.
[Brief description of the drawings]
FIG. 1 is a graph showing a dependence characteristic of Eu concentration of an emission spectrum of one embodiment according to the present invention.
FIG. 1 is a graph showing an Al concentration dependency characteristic of an emission spectrum of an example according to the present invention.

Claims (2)

At least europium (Eu) and reducing agent R (aluminum (Al), zinc (Zn), calcium (Ca), magnesium (Mg)) at the time of producing a sol-gel glass that emits light in the visible region by ultraviolet light excitation. In a sol-gel glass that causes blue light emission by divalent europium ions (Eu ²⁺ ) only by heat treatment for sol-gel glass production without performing heat treatment for reduction after glass production by using a starting solution containing When aluminum (Al) is used as the reducing agent and the final component of the sol-gel glass is expressed in terms of mol% of SiO ₂ : Al ₂ O ₃ : Eu ₂ O ₃ , Eu is 5 mol% or less in terms of Eu ₂ O _3. A blue light emitting sol-gel glass characterized in that Al is 10 mol% or less in terms of Al ₂ O ₃ and causes blue light emission. 2. The blue light emission according to claim 1, wherein blue light emission is caused by adding chlorine (Cl) as a raw material component of the sol-gel glass in order to sensitize light emission of the divalent europium ion (Eu ²⁺ ). Luminescent sol-gel glass.

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