JP6061624B2 - Transparent crystallized glass - Google Patents

Description

  The present invention relates to a transparent crystallized glass excellent in high-efficiency wavelength upward conversion characteristics, which is suitable for use in short-wavelength solid-state lasers, full-color displays, infrared light detection sensors, and the like.

  In recent years, wavelength up-conversion materials that use electronic transitions between multiple energy levels of rare earth ions can be applied in various fields such as blue and green solid-state lasers, full-color displays, and infrared light detection sensors. Because of the strong interest.

Conventionally, as the wavelength upward conversion transparent crystallized glass, lead fluoride-based transparent crystallized glass (for example, Patent Document 1) and strontium fluoride-based transparent crystallized glass (for example, Non-patent Document 1) are known.
However, lead fluoride-based transparent crystallized glass has low productivity due to low devitrification stability, and contains a large amount of toxic lead, so its application range is limited.
On the other hand, strontium fluoride-based transparent crystallized glass has relatively high wavelength up-conversion characteristics without using lead, but also has low devitrification stability and a very high melting temperature and volatilization. Due to the large variation in quality due to the above, it is very difficult to stably produce a practical size product, that is, a problem remains in terms of glass production stability.

Japanese Patent No. 3411067

"Journal of the Ceramic Society of Japan 115 (1346), 605-607, 2007-10-01"

  As described above, the conventional wavelength-up-converting transparent crystallized glass has low devitrification stability and contains a large amount of toxic lead or does not use lead. However, there was a problem that the production stability of the glass was poor.

  The present invention was developed in view of the above-mentioned present situation, and without using lead, has a high devitrification stability and wavelength up-conversion characteristics, and further has excellent production stability. As well as its advantageous production method.

The target characteristics in the present invention are as follows.
-Devitrification stability In the glass before heat treatment, the spectral transmittance at 600 nm at a glass thickness of 3 mm is 90% or more.
-Transparency In the crystallized glass after heat treatment, the spectral transmittance at 600 nm at a glass thickness of 3 mm is 90% or more.
-Wavelength up-conversion characteristics In the crystallized glass after heat treatment, the emission intensity when excited by an infrared laser (wavelength: 1064 nm, output: 0.9 W) is 0.0005 μW or more.

As a result of many experiments and studies to achieve the above object, the inventors have obtained the following knowledge.
(A) When an oxyfluoride glass containing rare earth ions is produced by a melting method, if an appropriate amount of B ₂ O ₃ is contained, the melting temperature is lowered, and the production stability of the glass, which has been regarded as a problem in the past, is reduced. Greatly improved.
(B) When B ₂ O ₃ is contained, particularly rare earth ions to be used are Er and Yb. By adding these in combination, it is possible to stably impart wavelength up-conversion characteristics to glass. it can.
The present invention is based on the above findings.

That is, the gist configuration of the present invention is as follows.
1. In mol%
SiO _2: 10~48% and B ₂ O _3: 2 to 40%
(SiO ₂ + B ₂ O ₃ ): 26 to 50%
Incorporated within a range that satisfies, and SrF _2: 25 to 45% and Al ₂ O _3: 15~35%
Er ₂ O ₃ : 0 to 5% and ErF ₃ : 0 to 5%
(Er ₂ O ₃ + ErF ₃ ): 0.01 to 5%
In a range that satisfies the requirements,
Yb ₂ O ₃ : 0 to 10% and YbF ₃ : 0 to 10%,
(Yb ₂ O ₃ + YbF ₃ ): 0.01 to 10%
In addition, AlF ₃ : 0 to 10%
A transparent crystallized glass having a composition containing strontium fluoride microcrystals containing rare earth ions.

2. A feature is that oxyfluoride glass containing rare earth ions is produced by a melting method, and then heat-treated at a temperature higher than the glass transition temperature, thereby precipitating strontium fluoride microcrystals containing rare earth ions in the glass. 2. The method for producing a transparent crystallized glass according to 1 above.

  According to the present invention, it is possible to obtain a transparent crystallized glass having high devitrification stability, excellent wavelength upward conversion characteristics, and excellent manufacturing stability without using toxic lead.

It is the figure which compared and showed the X-ray-diffraction pattern of Example glass (before heat processing) 9 and Example crystallized glass (after heat processing) 9. FIG. It is the figure which compared and showed the transmission spectrum of Example glass (before heat processing) 9 and Example crystallized glass (after heat processing) 9. FIG. It is the figure which showed and compared the emission spectrum of Example glass (before heat processing) 9 and Example crystallized glass (after heat processing) 9. FIG.

Hereinafter, the present invention will be specifically described.
First, the reason why the glass composition is limited to the above range in the present invention will be described. In addition, unless otherwise indicated, the "%" display regarding a component shall mean mol%.
SiO _2: 10~48%
SiO ₂ is a useful component capable of forming a glass network structure and imparting devitrification resistance that can be produced to glass. However, if its content exceeds 48%, the meltability may be reduced, or microcrystals may be difficult to precipitate. On the other hand, if it is less than 10%, the chemical and mechanical durability may be reduced, or the loss resistance may be reduced. Since there is a possibility that vitrification is lowered and vitrification becomes difficult, the content of SiO ₂ is limited to a range of 10 to 48%. Preferably it is 11-47 mol%, More preferably, it is the range of 12-46 mol%.

B ₂ O ₃ : 2 to 40%
In the present invention, B ₂ O ₃ is a particularly important component. This B ₂ O ₃ has a function of forming a glass network structure and imparting devitrification resistance that can be produced to glass, like SiO ₂ . Further, since the melting temperature of the glass can be increased and the melting temperature can be kept low, the production stability is improved. As a result, it is possible to suppress the volatilization of fluorine and suppress the deterioration of the wavelength upward conversion characteristics. However, if its content exceeds 40%, the stability of devitrification may decrease and vitrification may become difficult. On the other hand, if it is less than 2%, the effect of improving meltability may not be obtained. The content of B ₂ O ₃ was limited to a range of 2 to 40%. Preferably it is 3-38%, More preferably, it is the range of 4-36%.

(SiO ₂ + B ₂ O ₃ ): 26 to 50%
On the other hand, if the total amount of SiO ₂ and B ₂ O ₃ exceeds 50%, microcrystals may be difficult to precipitate. On the other hand, if the total amount is less than 26%, devitrification resistance decreases and vitrification becomes difficult. Therefore, the total amount of these is set to a range of 26 to 50%. Preferably it is 27 to 49%, more preferably 28 to 48%.

SrF ₂ : 25 to 45%
In the present invention, SrF ₂ is a particularly important component. This SrF ₂ not only enhances the devitrification stability and meltability of the glass, but is an essential component for the precipitation of microcrystals. However, if its content exceeds 45%, the mechanical durability may decrease, or the stability of devitrification may decrease and vitrification may be difficult. On the other hand, if the content is less than 25%, the meltability decreases. In other words, the SrF ₂ content is limited to a range of 25 to 45%. Preferably it is 26 to 44%, more preferably 27 to 43%.

Al ₂ O ₃ : 15 to 35%
Al ₂ O ₃ has the effect of improving the devitrification resistance and chemical and mechanical durability of the glass as a modified oxide as well as forming a network structure of glass. However, if its content exceeds 35%, the meltability may be reduced, or microcrystals may be difficult to precipitate. On the other hand, if it is less than 15%, the chemical and mechanical durability may be reduced, and the loss resistance may be reduced. Since the permeability stability is lowered and vitrification may be difficult, the content of Al ₂ O ₃ is limited to a range of 15 to 35%. Preferably it is 16 to 34%, more preferably 17 to 33% of range.

Er ₂ O ₃ : 0 to 5%, ErF ₃ : 0 to 5%, and (Er ₂ O ₃ + ErF ₃ ): 0.01 to 5%
Both Er ₂ O ₃ and ErF ₃ are sources of Er ³⁺ which is a luminescent component. However, if the content exceeds 5%, there is a possibility that the wavelength up-conversion characteristics may be deteriorated due to concentration quenching. Therefore, the contents of Er ₂ O ₃ and ErF ₃ are set in the range of 0 to 5%, respectively. Preferably it is 0 to 4.5%, More preferably, it is 0 to 4% of range.
On the other hand, if the total amount of Er ₂ O ₃ and ErF ₃ exceeds 5%, the wavelength up-conversion characteristics may be reduced due to concentration quenching. On the other hand, if the total amount is less than 0.01%, Er ³ , which is a light emitting component. ^{Since the +} content is small and there is a possibility that the wavelength upward conversion characteristics may not be exhibited, the total amount is set in the range of 0.01 to 5%. Preferably it is 0.05 to 4.5%, More preferably, it is 0.05 to 4% of range.

Yb ₂ O ₃ : 0 to 10%, YbF ₃ : 0 to 10%, and (Yb ₂ O ₃ + YbF ₃ ): 0.01 to 10%
Yb ₂ O ₃ and YbF ₃ are both sources of Yb ^{3+ that} act as sensitizers. However, if the content exceeds 10%, the devitrification resistance stability of the glass may be lowered and vitrification may be difficult. Therefore, the content of Yb ₂ O ₃ and YbF ₃ is 0 to 10%, respectively. Range. Preferably it is 0 to 9.5%, more preferably 0 to 9% of range.
On the other hand, if the total amount of Yb ₂ O ₃ and YbF ₃ exceeds 10%, the devitrification resistance stability of the glass may be lowered and vitrification may be difficult. Therefore, the total amount of Yb ³⁺ acting as the above may be in the range of 0.01 to 10%. Preferably it is 0.5 to 9.5%, more preferably 0.5 to 9%.

AlF ₃ : 0 to 10%
AlF ₃ has the effect of improving the chemical durability and meltability of glass as a source of F ⁻ ions. However, when the content exceeds 10%, the devitrification resistance may be deteriorated. Further, when a necessary amount of F ⁻ ions are supplied from the above-described SrF ₂ , ErF ₃ , YbF _3, etc., this AlF ₃ is not necessarily contained. Therefore, the content of AlF ₃ is set in the range of 0 to 10%. Preferably it is 9% or less, More preferably, it is 8% or less.

Next, the manufacturing method of the transparent crystallized glass of this invention is demonstrated.
In the present invention, as a method for obtaining a highly efficient wavelength upward-converting transparent crystallized glass, oxides, hydroxides, carbonates, nitrates, fluorides, and the like corresponding to the raw materials of each component are weighed at a predetermined ratio, A well-mixed material is used as a glass preparation raw material. Next, this raw material is preferably put into a platinum crucible or a gold crucible, heated to 1200 to 1400 ° C. in an electric furnace and stirred while being melted, then clarified and homogenized in an electric furnace, After casting into a mold preheated to temperature, it is slowly cooled in an electric furnace to remove strain.
Up to this point, a transparent glass having various shapes is obtained by using almost the same manufacturing method as that of a normal oxide glass. However, in the present invention, since an appropriate amount of B ₂ O ₃ is contained in the raw material, the melting temperature is set. It can be kept lower than before. Incidentally, the conventional melting temperature was about 1400 to 1600 ° C.

Next, the obtained transparent glass is further heat-treated for several hours in a temperature range higher than the glass transition temperature and lower than the crystallization temperature and not devitrifying. Suitable heat treatment conditions are 500 to 700 ° C. and 3 to 12 hours.
By this heat treatment, the luminous efficiency of the rare earth can be remarkably improved without any loss of transparency.

  This is because a large amount of fluoride crystallites containing rare earth ions in the glass was precipitated by the heat treatment. Note that the microcrystalline particles deposited in the transparent crystallized glass have a size smaller than the wavelength of light and are so small that it is negligible to scatter visible light. It has the same transparency.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and the transparent crystallized glass of this invention is demonstrated concretely, this invention is not limited to these Examples.

The raw materials are weighed so that the total amount of the oxides and fluorides described in Tables 1 and 3 is 100 g, mixed well, then put into a platinum crucible, and heated at 1200 to 1400 ° C. for 1 to 2 hours in an electric furnace. After melting, stir, melt for an additional 1-2 hours, stir properly, homogenize, clarify, and cast into a mold preheated to 550 ° C, then slowly cool in an electric furnace Example glass (before heat treatment) 1 to 12 and comparative glass (before heat treatment) 1 to 5 were obtained.
Next, the obtained glass was further subjected to a heat treatment at a temperature of 650 ° C. for 3 hours, and then allowed to cool to room temperature, whereby Example crystallized glass (after heat treatment) 1 to 12 and Comparative Example crystallized glass ( 1-5 were obtained after heat treatment.

Tables 2 and 4 show the results of examining the melting temperature at the time of the melting treatment, the devitrification stability of the glass before the heat treatment, the transparency of the crystallized glass after the heat treatment, and the wavelength upward conversion characteristics (luminescence intensity).
Each characteristic was evaluated as follows.
(1) Devitrification stability The glass before heat treatment was evaluated with a spectral transmittance of 600 nm at a thickness of 3 mm. In addition, the spectrophotometer U-4100 (made by Hitachi) was used for the measurement.
○: Spectral transmittance is 90% or more Δ: Spectral transmittance is 50% or more and less than 90% ×: Spectral transmittance is less than 50%

(2) Transparency The crystallized glass after the heat treatment was evaluated with a spectral transmittance of 600 nm at a thickness of 3 mm. In addition, the spectrophotometer U-4100 (made by Hitachi) was used for the measurement.
○: Spectral transmittance is 90% or more Δ: Spectral transmittance is 50% or more and less than 90% ×: Spectral transmittance is less than 50%

(3) Wavelength upward conversion characteristics Each crystallized glass was evaluated by the emission intensity of 550 nm when excited by an infrared laser. An Nd: YAG laser with a wavelength of 1064 nm and an output of 0.9 W was used for excitation, and an optical spectrum analyzer AQ-6315A (manufactured by ANDO) was used for measurement of emission intensity.
○: Emission intensity is 0.0005 μW or more Δ: Emission intensity is 0.0001 μW or more and less than 0.0005 μW ×: Emission intensity is less than 0.0001 μW

  As shown in Table 2, all of the example crystallized glasses obtained according to the present invention have a melting temperature of 1400 ° C. or less, have devitrification resistance that can be produced, and can be used for transparency. And wavelength up-conversion characteristics (emission intensity).

On the other hand, the comparative example crystallized glasses 1 to 5 shown in Table 4 had the following problems.
Since the comparative example crystallized glass 1 has a large content of SiO ₂ and SiO ₂ + B ₂ O ₃ , the emission intensity is low.
Since the comparative example crystallized glass 2 has a low content of SiO ₂ and SiO ₂ + B ₂ O ₃ , it has low devitrification stability and low transparency.
Since the comparative example crystallized glass 3 does not contain B ₂ O ₃ , the melting temperature is very high, the devitrification resistance is low, and the transparency is also low.
Since the comparative example crystallized glass 4 has a low SrF ₂ content, the emission intensity is low.
Since the comparative example crystallized glass 5 has a large content of Er ₂ O ₃ and Er ₂ O ₃ + ErF ₃ , the emission intensity is low.

FIG. 1 shows a comparison of X-ray diffraction patterns of Example Glass (before heat treatment) 9 and Example Crystallized Glass (after heat treatment) 9. For the measurement, a powder X-ray diffractometer Ultima IV (manufactured by Rigaku) was used, and CuKα (40 kV-50 mA) was used as the X-ray source.
As is clear from FIG. 1, the example glass (before heat treatment) 9 is in a glass state because no diffraction peak is observed. On the other hand, in Example crystallized glass 9 after heat treatment (after heat treatment), since a sharp diffraction peak due to strontium fluoride crystals is observed, it can be seen that crystals are precipitated inside the glass.

FIG. 2 shows a comparison of transmission spectra of Example Glass (before heat treatment) 9 and Example Crystallized Glass (after heat treatment) 9 at a thickness of 3 mm. In addition, the spectrophotometer U-4100 (made by Hitachi) was used for the measurement.
As is clear from FIG. 2, there is no significant difference in transmittance between the example glass (before heat treatment) 9 and the example crystal glass (after heat treatment) 9. That is, no decrease in transmittance due to crystal precipitation is observed.

FIG. 3 shows a comparison of emission spectra of Example Glass (before heat treatment) 9 and Example Crystallized Glass (after heat treatment) 9. A YAG laser having a wavelength of 1064 nm and an output of 0.9 W was used for excitation, and an optical spectrum analyzer AQ-6315A (manufactured by ANDO) was used for spectrum measurement.
As is clear from FIG. 3, the example glass (before heat treatment) 9 does not emit light, whereas the example crystallized glass (after heat treatment) 9 shows clear light emission at around 550 nm and 650 nm. Thus, it can be seen that the emission intensity of the rare earth is remarkably improved by the crystal precipitation.

Claims (2)

In mol%
SiO _2: 10~48% and B ₂ O _3: 2 to 40%
(SiO ₂ + B ₂ O ₃ ): 26 to 50%
Incorporated within a range that satisfies, and SrF _2: 25 to 45% and Al ₂ O _3: 15~35%
Er ₂ O ₃ : 0 to 5% and ErF ₃ : 0 to 5%
(Er ₂ O ₃ + ErF ₃ ): 0.01 to 5%
In a range that satisfies the requirements,
Yb ₂ O ₃ : 0 to 10% and YbF ₃ : 0 to 10%,
(Yb ₂ O ₃ + YbF ₃ ): 0.01 to 10%
In addition, AlF ₃ : 0 to 10%
Transparent crystallized glass comprising only a composition containing strontium fluoride microcrystals containing rare earth ions.   A feature is that oxyfluoride glass containing rare earth ions is prepared by a melting method, and then heat-treated at a temperature higher than the glass transition temperature, thereby precipitating strontium fluoride microcrystals containing rare earth ions in the glass. The manufacturing method of the transparent crystallized glass of Claim 1.

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