JP2006248800A - Blue fluorescent glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blue fluorescent glass which, when irradiated with an intense ultraviolet radiation such as excimer lasers, does not change in a fluorescent color, is not broken, and exhibits a high efficiency of conversion from an ultraviolet radiation into a blue light and high fluorescent intensity. <P>SOLUTION: The blue fluorescent glass comprises (expressed in terms of mol%) 15 to 55 of AlF<SB>3</SB>, 0 to 20 of MgF<SB>2</SB>, 0 to 25 of CaF<SB>2</SB>, 0 to 20 of SrF<SB>2</SB>, 0 to 35 of BaF<SB>2</SB>, 0 to 15 of RX<SB>2</SB>(R is at least one element selected from among Mg, Ca, Sr, and Ba; and X is at least one element selected from among Cl, Br, and I), 0 to 25 of LnF<SB>3</SB>(wherein Ln is at least one element selected from among Y, La, Gd, Yb, Lu, and Dy), and 0.01 to 5 of EuX'<SB>3</SB>(wherein X' is at least one element selected from among F, Cl, Br, and I). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a material for converting ultraviolet light into visible light with high efficiency, which is used as a phosphor or an optical sensor for a display or a lighting fixture, and particularly to blue fluorescent glass that emits blue light.

In general, phosphors that are put to practical use for displays and lamps are mainly composed of sulfide, oxysulfide, or halophosphate as a base material, and a rare earth element as a luminescent center. As a phosphor emitting blue light, ZnS: Ag ⁺ is put into practical use for displays, and BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ is put into practical use for lamps. However, these phosphors are opaque powders, and are used by applying the powders on a substrate. Therefore, the use is limited to the case of using fluorescence emitted from the surface of the phosphors. Yes. (Non-Patent Document 1)
As means for solving this problem, JP-B-57-27047, JP-B-57-27048, JP-A-9-202642, and JP-A-10-167755 disclose not only the surface but also the inside. A transparent fluorescent glass that emits light is disclosed.
The fluorescent glass disclosed in JP-B-57-27047, JP-B-57-27048, and JP-A-10-167755 is a transparent fluorescent glass obtained by adding rare earth ions to oxide glass, Product, an optical component for adjusting the optical axis of an ultraviolet laser such as an excimer laser, and the like.

The phosphor disclosed in Japanese Patent Laid-Open No. 9-202642 is a transparent blue fluorescent glass obtained by adding rare earth ions to a fluorophosphate glass, and is used for an optical component for adjusting an optical axis of an ultraviolet laser such as an excimer laser. Can do.
Phosphor Handbook, Ohmsha, 1987, 3rd edition: Practical phosphor, 165 Japanese Patent Publication No.57-27047 Japanese Patent Publication No.57-27048 JP-A-9-206422 Japanese Patent Laid-Open No. 10-167755

Europium (hereinafter abbreviated as Eu) ions are usually in a trivalent state, and trivalent Eu ions exhibit red fluorescence when excited by ultraviolet rays. In order for a phosphor having an emission center of Eu ions to emit blue light, the Eu ions need to be in a divalent state.
When the oxide glass to which Eu ions are added melts in the atmosphere, trivalent Eu ions are most stable. Even if the melting atmosphere is made reducible or a reducing agent is added to the raw material, divalent and trivalent Eu ions are mixed. In oxide glass, it is difficult to make most of the Eu ions bivalent.
The fluorophosphate glass has a band gap energy between the valence band and the conduction band that is smaller than that of fluoride glass due to the action of the electron orbit of phosphorus and oxygen. The transmittance in the ultraviolet region decreases. When the transmittance of the base glass in the ultraviolet region is small, the base glass absorbs excitation ultraviolet light, excites lattice vibrations, converts the ultraviolet light into heat, and generates heat. When ultraviolet light was irradiated for a long time, there was a problem that the glass was extremely heated and cracked.
In addition, fluorophosphate-based blue fluorescent glass has low conversion efficiency to blue light such as an excimer laser having an oscillation wavelength of 193 nm or 248 nm, and excites lattice vibrations to convert ultraviolet light into heat and generate heat. When ultraviolet light was irradiated for a long time, there was a problem that the glass was extremely heated and cracked.
Furthermore, the fluorophosphate-based blue fluorescent glass has a problem that the fluorescent color changes from blue to red due to oxidation of divalent Eu ions, which are the emission center, to trivalent by irradiation with strong ultraviolet light such as excimer laser. there were.
Furthermore, fluorophosphate-based blue fluorescent glass has low fluorescence intensity, and it is necessary to improve the conversion efficiency and emission intensity of ultraviolet light into blue light for application to fluorescent display panels and ultraviolet power monitor sensors. there were.
The present invention has been made to solve the above-mentioned problems, and provides a blue fluorescent glass having a fluorescent intensity that does not change due to irradiation of intense ultraviolet light such as an excimer laser, does not break the glass, and has a high fluorescent intensity. The purpose is to do.

In the present invention, AlF ₃ is 15 to 55, MgF ₂ is 0 to 20, CaF ₂ is 0 to 25, SrF ₂ is 0 to 20, BaF ₂ is 0 to 35, and RX ₂ is 0 to 15 in terms of mol%. (However, R is one or more elements selected from Mg, Ca, Sr, and Ba, X is one or more elements selected from Cl, Br, and I), and LnF ₃ is 0 to 25 (where Ln is One or more elements selected from Y, La, Gd, Yb, Lu, and Dy), and EuX ′ ₃ is 0.01 to 5 (where X ′ is one or more elements selected from F, Cl, Br, and I). It is a fluorescent glass characterized by exhibiting blue fluorescence by ultraviolet light excitation.

  The fluorescent glass of the present invention can convert ultraviolet light into blue light with high efficiency, and has high fluorescence intensity. Further, even when irradiated with intense ultraviolet light, there is no change in fluorescent color or breakage of the glass, and the durability is excellent.

  The blue fluorescent glass of the present invention is a halide glass whose main material is aluminum fluoride as a main component, and is obtained by adding divalent Eu ions as an activator.

  Hereinafter, the reason why the base glass of the blue fluorescent glass is selected as described above and the constituent component ranges are limited will be described. In addition, unless otherwise indicated, the display of a component component range is mol%.

Since the fluoride material has a larger band gap energy than the oxide material and the sulfide material, the wavelength of the absorption edge on the ultraviolet side is short and it is more transparent to ultraviolet light. When the light absorption is small, the heat generation of the material due to the light absorption is small when irradiated with strong ultraviolet light typified by an excimer laser, and the possibility that the base material is damaged by the heat generation is small. Therefore, a fluoride material was selected as the base material of the blue fluorescent glass of the present invention.
Since fluoride glass has a low polarizability of fluorine ions, the rare earth ions added are relatively stable in the divalent state, and most of the Eu ions can exist in the divalent state. In addition, as compared with an oxide having both ionic bonding properties and covalent bonding properties, fluoride has strong ionic bonding properties, so that the cations forming the base material are less likely to be reduced. Therefore, fluoride glass was selected as the base material of the blue fluorescent glass of the present invention.

Aluminum fluoride (AlF ₃ ) is a glass forming component. If AlF ₃ does not reach 15 mol%, crystallization tends to occur, and if it exceeds 55 mol%, the solubility becomes poor. Preferably, it is 30-40 mol%.

Fluorides such as hafnium fluoride (HfF ₄ ), zirconium fluoride (ZrF ₄ ), and indium fluoride (InF ₃ ) are also glass-forming components, but AlF ₃ has a higher transmittance in the ultraviolet region than these fluorides. And chemical weather resistance is excellent. In addition, since AlF3 has an electron affinity of aluminum smaller than that of trivalent Eu ions, the trivalent Eu ions are preferentially reduced to divalent. Furthermore, since glass with AlF3 as the main component has a lower lattice vibration energy than oxide-based glass, excited electrons from ultraviolet light emit thermal energy due to non-radiative relaxation that involves coupling with lattice vibration. To suppress inactivation. As a result, much of the excitation energy of ultraviolet light is converted into photon energy, and the fluorescence intensity from the emission center increases. That is, AlF ₃ increases the conversion efficiency of ultraviolet light into visible light and increases the fluorescence intensity.

MgF ₂ , CaF ₂ , SrF ₂ , and BaF ₂ are components that improve the solubility of the glass. When MgF ₂ , CaF ₂ , SrF ₂ , and BaF ₂ exceed 20 mol%, 25 mol%, 20 mol%, and 35 mol%, respectively, phase separation and crystallization are likely to occur, and the stability of the glass is lowered. To do. _{MgF 2, CaF 2, SrF 2} , and preferred components of BaF _2, respectively, 5 to 15 mol%, 5 to 20 mol%, 5 to 15 mol%, and 5 to 20 mol%, it is.

The halogen elements Cl, Br, and I are more effective than F in promoting the reduction of trivalent Eu ions, and the ability is enhanced in the order of F <Cl <Br <I. Further, Cl, Br, and I are more effective than F in enhancing blue fluorescence from divalent Eu ions. RX ₂ (where R is one or more atoms selected from alkaline earth metal elements such as Mg, Ca, Sr, Ba, etc. X is a type selected from halogen elements such as F, Cl, Br, I, etc.) When the total amount of the above atoms) exceeds 15 mol%, phase separation and crystallization are likely to occur. A preferred total amount of RX ₂ is 0-10 mol%.

LnF ₃ (where Ln is one or more elements selected from Y, La, Gd, Yb, Lu, and Dy) is a component that suppresses crystallization of glass. When these components exceed 25 mol%, crystallization tends to occur. Since LnF ₃ even if a small amount tends to crystallize, preferred components of LnF ₃ is 5 to 20 mol%.

EuX ′ ₃ (where X ′ is one or more atoms selected from halogen elements such as F, Cl, Br, and I) is a component that exhibits visible light fluorescence by excitation of ultraviolet light. Divalent Eu ions exhibit blue fluorescence, and trivalent Eu ions exhibit red fluorescence. If EuX ′ ₃ does not reach 0.01 mol%, sufficient fluorescence intensity cannot be obtained, and if it exceeds 5 mol%, trivalent Eu ions are mixed, and both blue and red fluorescence intensities decrease. Preferably, it is 0.1-0.5 mol%.

  In addition, each said component is adjusted in the range of each component so that it may become the fluorescent glass whose sum total of a component amount is 100 mol%.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this Example. Table 1 shows the blue fluorescent glass (samples Nos. 1 to 14) of the examples of the present invention expressed in mol%. Table 2 shows the blue fluorescent glass (samples Nos. 1 to 14) of the examples of the present invention expressed in weight%.
(Example 1) The compounds shown in Table 2 were used as raw materials, and the raw materials were prepared so as to have a weight ratio of No. 1 in Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was visually confirmed that this glass emits strong blue light when excited with ultraviolet light having a wavelength of 365 nm. The fluorescence spectrum is shown by a solid line in FIG. In FIG. 1, a broad peak at 413 nm, which is a solid line, indicates light emission due to Eu ²⁺ : 4f5d → 4f transition.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. The fluorescence spectrum is shown by a solid line in FIG. Fluorescence spectra of the solid line in FIG. 2 ^Eu 2+: 4f5d → 4f transition by showing an emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition confirmed There wasn't. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
(Examples 2 to 6) The compounds shown in Table 2 were used as raw materials, and the raw materials were prepared so as to have the weight ratios shown in Nos. 2 to 6 in Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was visually confirmed that this glass emits strong blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. As in Example 1, the fluorescence spectrum showed light emission due to Eu ²⁺ : 4f5d → 4f transition at 413 nm. Its strength was 3/4 of the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. Its fluorescence spectrum, as in Example ^1, Eu 2+: 4f5d → 4f transition by showing an emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition Could not be confirmed. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
(Examples 7 to 9) The compounds shown in Table 2 were used as raw materials, and the raw materials were prepared so as to have the weight ratios shown in Nos. 7 to 9 in Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was visually confirmed that this glass emits strong blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. As in Example 1, the fluorescence spectrum showed light emission due to Eu ²⁺ : 4f5d → 4f transition at 413 nm. Its strength was almost the same as the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. Its fluorescence spectrum, as in Example ^1, Eu 2+: 4f5d → 4f transition due represents the emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition Could not be confirmed. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
(Example 10) Using the compounds shown in Table 2 as raw materials, the raw materials were prepared so as to have the weight ratios shown in No. 10 of Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was visually confirmed that this glass emits strong blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. As in Example 1, the fluorescence spectrum showed light emission due to Eu ²⁺ : 4f5d → 4f transition at 413 nm. Its strength was 3/4 of the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. Its fluorescence spectrum, as in Example ^1, Eu 2+: 4f5d → 4f transition by showing an emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition Could not be confirmed. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
(Examples 11 to 12) The compounds shown in Table 2 were used as raw materials, and the raw materials were prepared so as to have the weight ratios shown in No. 11 to No. 12 of Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was confirmed by visual observation that this glass emits blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. As in Example 1, the fluorescence spectrum showed light emission due to Eu ²⁺ : 4f5d → 4f transition at 413 nm. Its strength was ¼ that of the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. Its fluorescence spectrum, as in Example ^1, Eu 2+: 4f5d → 4f transition by showing an emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition Could not be confirmed. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
Examples 13 to 14 The compounds shown in Table 2 were used as raw materials, and the raw materials were prepared so as to have the weight ratios shown in No. 13 to No. 14 of Table 2. In order to fluorinate and remove impurities such as oxygen and moisture in the raw material, it was added to 30 g of a batch prepared by adding 0.15 g of acidic ammonium fluoride (NH ₄ F · HF) as a fluorinating agent. This batch is put into a crucible made of glassy carbon, heated and melted at 1000 ° C. for 30 minutes in a gas atmosphere of hydrogen and nitrogen having a hydrogen concentration of 3%, and then rapidly cooled in a nitrogen atmosphere to obtain Eu ²⁺ . The contained glass was obtained. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

It was confirmed by visual observation that this glass emits blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. As in Example 1, the fluorescence spectrum showed light emission due to Eu ²⁺ : 4f5d → 4f transition at 413 nm. Its strength was 2/4 of the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. During the irradiation, strong blue fluorescence was confirmed from the glass. Its fluorescence spectrum, as in Example ^1, Eu 2+: 4f5d → 4f transition by showing an emission _{^{only, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) emission by transition Could not be confirmed. Even after 3 minutes of irradiation, the fluorescence spectrum did not change and the glass was not damaged.
Comparative Example 1 Conventionally known glass composition, that is, Al (PO ₃ ) ₃ : 1.12%, Ba (PO ₃ ) ₂ : 1.00%, AlF ₃ : 32.23%, MgF ₂ : Raw materials prepared according to 6.51%, CaF ₂ : 24.84%, SrF ₂ : 22.24%, BaCl ₂ : 12.00%, Eu ₂ O ₃ : 0.06% were melted at 900 to 1300 ° C. The glass was obtained by pouring out into a graphite mold. The glass was then cut into a size of 20 mm × 20 mm × 3 mm and both sides were optically polished.

This glass emitted blue light when irradiated with ultraviolet light having a wavelength of 365 nm under the same conditions as in Example 1. The fluorescence spectrum is shown by a broken line in FIG. The broad peak at 413 nm shown by the broken line in FIG. 1 indicates light emission due to the Eu ²⁺ : 4f5d → 4f transition, but the intensity thereof is about ¼ that of the glass of Example 1.

Next, the produced glass was irradiated with a KrF excimer laser having a wavelength of 248 nm to investigate the ultraviolet light resistance. The irradiation conditions were an irradiation energy of 250 mJ / cm ² and a repetition frequency of 10 Hz. Immediately after the start of irradiation, strong blue fluorescence could be confirmed from the glass, but the emission color changed from blue to pink over time. The fluorescence spectrum is shown by a broken line in FIG. Fluorescence spectra of the broken line in FIG. ^2, Eu 2+: 4f5d → 4f well emission by the _{^{transition, Eu 3+: 5 D 0 →}} 7 F J (J = 0,1,2,3,4) also shows emission by transition It was. When irradiation was continued, after 30 seconds, the irradiated area cracked and the glass was broken.

  In this example, La or Gd was used as the rare earth element other than Eu serving as the light emission center. You can also use it.

In this example, the halide of the rare earth element was LnF ₃ of fluoride (where Ln is one or more elements selected from Y, La, Gd, Yb, Lu, and Dy). A compound with a halogen element such as Cl, Br, or I in the same group can also be used.

Further, the volatile product resulting from the reaction with the fluorinating agent, the mixing of a trace amount of oxygen atoms that cannot be avoided even by melting in a reducing atmosphere, and the mixing of Fe ₂ O ₃ , MnO ₂ , and other impurities, This does not hinder the present invention.

Fluorescence spectrum when blue fluorescent glass is excited with ultraviolet light having a wavelength of 365 nm. (The solid line in the figure is Example 1, and the broken line in the figure is Comparative Example 1) Fluorescence spectrum when blue fluorescent glass is excited with a KrF excimer laser having a wavelength of 248 nm. (The solid line in the figure is Example 1, and the broken line in the figure is Comparative Example 1)

Claims (1)

In terms of mol%, AlF ₃ is 15 to 55, MgF ₂ is 0 to 20, CaF ₂ is 0 to 25, SrF ₂ is 0 to 20, BaF ₂ is 0 to 35, RX ₂ is 0 to 15 (however, R Is one or more elements selected from Mg, Ca, Sr and Ba, X is one or more elements selected from Cl, Br and I, and LnF ₃ is 0 to 25 (where Ln is Y, La, One or more elements selected from Gd, Yb, Lu and Dy), EuX ′ ₃ is 0.01 to 5 (where X ′ is one or more elements selected from F, Cl, Br and I), and ultraviolet A fluorescent glass which exhibits blue fluorescence by photoexcitation.