JP3928741B2 - Method for producing silica glass for laser - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for producing a rare earth-containing composition, more particularly optical characteristics, nonlinear optical properties, a method for manufacturing of electrical or rare earth-containing composition containing a rare earth element having characteristics such as a magnetic characteristic.
[0002]
[Prior art]
In recent years, many compositions have been developed that contain functional elements in a medium such as glass or ceramics and have been imparted with properties such as optical properties, nonlinear optical properties, electrical or magnetic properties, and are being used for various applications. For example, a multi-component silicate or phosphate glass containing alkaline earth oxide or the like, a laser glass doped with rare earth elements such as Nd and Ce on silica glass, Cs ⁺ , Tl ⁺ , Pb ²⁺ etc. on the glass Examples thereof include a doped high refractive index glass, a ceramic light emitting device containing a functional element, a ferrite, a ceramic optical isolator, and a PZT device.
[0003]
[Problems to be solved by the invention]
However , since rare earth elements have a high ionic valence, they are generally easily associated in a non-polar medium, resulting in local microcrystals. When such local microcrystals are generated, for example, when trying to impart characteristics such as laser oscillation to a medium, rare earth elements do not participate in light emission, and work exclusively as light absorbers, and the efficiency of laser oscillation is remarkably increased. In addition to lowering, in extreme cases, local crystallization occurs that inhibits the function of the composition. For example, in the case of glass, transparency and the like are hindered by the occurrence of cloudiness and scatterers. As means for preventing such rare earth element association, a method of co-doping Al or P as a rare earth element association inhibitor in a medium has been proposed in JP-A-60-11245. The method described in the above publications is a method of reacting a mixed gas of a rare earth element compound and a silicon compound with a mixed gas of an Al compound or a P compound with an oxidation plasma flame to vitrify, and Al or P is distributed to the rare earth element. To prevent the rare earth elements from meeting together. In addition to the method described in the above publication, a CVD method in which NdCl ₃ is introduced into an oxyhydrogen flame in the form of a solid and doped into silica fine particles generated by flame hydrolysis of a silicon compound, and soot is doped in an aqueous solution of a rare earth element salt. A method for producing a rare earth element-containing composition such as a stuffing method for pickling has been proposed.
[0004]
However, among the above methods, in the melting method or the CVD method, when the rare earth element at the time of melting is a solid, it is already contained in an associated state, so that it is melted as it is, so that the association is likely to occur. Even if it exists, sufficient effect cannot be exhibited. Further, in the plasma method, since the reaction of the raw material compound is fast, it is difficult to produce a rare earth element-containing composition having a high probability of Nd association and no association. Furthermore, the stuffing method cannot produce a rare earth element-containing composition in which doped elements are deposited in the drying stage of the doped soot and are associated with each other. Such functional degradation due to the association of rare earth elements is not limited to the glass, but is also a phenomenon that occurs in ceramics containing rare earth elements and utilizing their characteristics.
[0005]
In view of the current situation, the present inventors have conducted extensive research, and as a result, the rare earth element was previously fixed in a stable coordination field of the zeolite and doped into the medium in that state, so that it could be associated even at high concentrations. The present invention has been completed by finding that a rare earth element-containing composition can be produced. That is, [0006]
The present invention aims to provide a method for producing a rare earth-containing composition contained no rare earth element is associated.
[0007]
The present invention aims at providing a method for producing rare earth-containing silica glass contained no rare earth element is associated.
[0008]
An object of this invention is to provide the manufacturing method of the laser silica glass in which rare earth elements are contained in high concentration without associating.
[0009]
An object of this invention is to provide the manufacturing method of the laser silica glass which can oscillate a large sized high output laser.
[0010]
[Means for Solving the Problems]
The present invention for achieving the above object relates to a method for producing a rare earth element-containing composition, characterized by mixing and firing a zeolite in which a rare earth element is fixed and a medium raw material.
[0011]
The rare earth element is a metal element of Group III to V of the periodic table that exhibits optical characteristics, nonlinear optical characteristics, electrical or magnetic characteristics, etc. with a small amount of dope, and can be ion-exchanged with alkali ions of zeolite. An element. Moreover, that the rare earth element is fixed means that it is fixed at the site of the zeolite. In particular, the SI site of zeolite forms a stable coordination field, and the rare earth element fixed thereto is fixed in a stable state. As the fixing method, there is a method in which a water-soluble compound such as a rare earth element chloride, nitrate, hydroxide or the like and zeolite are heated in water to ion-exchange the alkali element and rare earth element of the zeolite. In the fixing method, when the fixed number is equal to or more than the desired number, it is preferable to control the number by treating with ammonia chloride solution. In the case of 9 which is the optimum fixed number, it is better to treat with a saturated ammonium chloride solution. In the fixing, when a rare earth element and an insensitive element are used in combination, the number of fixings can be controlled without the ammonia chloride treatment.
[0012]
Examples of the zeolite used in the production method of the present invention include faujasite type zeolite and cyclodextrin having similar properties to the faujasite. In particular, faujasite is preferable, and faujasite A {(Na ₂ , K ₂ , Ca, Mg) _29.5 [(AlO ₂ ) ₅₉ (SiO ₂ ) ₁₃₂ ] · 235H ₂ O}, faujasite X {Na ₈₆ [(AlO ₂ ) ₈₆ (SiO ₂ ) ₁₀₆ ] · 246H ₂ O} or faujasite Y {Na ₅₆ [(AlO ₂ ) ₅₆ (SiO ₂ ) ₁₃₆ ] · 250H ₂ O} is used. As shown in FIG. 1, the faujasite type zeolite has a hexagonal column of D6R in an incomplete octahedron shape connected to a regular tetrahedron. There are 5 sites such as SI, SII, SII ′, etc. in the site of the faujasite type zeolite, and there are 16 SI sites per unit cell. The maximum number of rare earth elements fixed to this faujasite is 28.7. Although it is preferable rare earth element stably fixed to the faujasite is fixed to SI sites 16 in the zeolite, when in all SI site to fix the rare earth elements occur that withdrawal of the resulting rare-earth elements Since association occurs, it is preferable to fix 3 to 14, preferably 9 rare earth elements of the SI site.
[0013]
As described above, the rare earth element is fixed to the SI site of the zeolite, that is, composed of an aluminosiloxane hexagonal column structure (a structure in which 6 out of 12 vertices are Al and the remaining 6 are occupied by Si). By fixing it to the central SI site and firing the silica raw material, the soot structure is doped into silica glass in a state where the periphery of the rare earth element is covered with another element, and between Nd and Nd The distance is over 9.3 km and there will be no meetings. When the zeolite to which the rare earth element is fixed is used, the rare earth element can be doped without associating in the range of 0.1 to 4 wt%. When the doping concentration is less than 0.1 wt%, the characteristics of rare earth elements cannot be exhibited, and when the doping concentration exceeds 4 wt%, the vitreous region is exceeded and no silica glass is formed.
[0014]
As silica raw materials used in the present invention, silica using an alkali silicate as a silica source, silica using an alkoxysilane as a silica source, a silane compound such as Si (CH ₃ ) Cl ₃ , SiCl ₄ as a silica source, a CVD method, VAD Examples thereof include silica produced by the method and natural crystalline quartz. In particular, in the case of a silica raw material using alkoxysilane as a silica source, a glass raw material in which zeolite is uniformly mixed by mixing and gelling a zeolite in which a functional rare earth element is fixed to a silica sol obtained by hydrolyzing alkoxysilane. The obtained silica glass is fired or mixed and fired with other silica raw materials to obtain a silica glass in which a rare earth element is homogeneously doped. In the said manufacture, after drying the obtained gel at 100-400 degreeC, after prebaking, it is good to grind | pulverize and make a particle size into the range of 50-250 micrometers. In addition, a range of 1400 to 1600 ° C. is selected as the pre-baking temperature. The silica glass is fired in the range of 1700 to 1800 ° C. When the medium is ceramic, a normal firing temperature is employed. In particular, in the firing of silica glass, it is preferable to employ the Bernoulli method because a silica glass in which rare earth elements are uniformly dispersed can be produced.
[0015]
In the production method of the present invention, not only can be homogeneously containing a rare earth element, how doping, doped with a rare earth element according to the intended use etc. doped compositions varying the concentration of the rare earth element, for example the circumferential direction can do. As a result, it is possible to produce a plate lens having a different refractive index in the circumferential direction.
[0016]
[Embodiment]
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to this.
[0017]
【Example】
Example 1
156 g of faujasite X and 477 g of NdCl ₃ were kept for 2 weeks while refluxing at 100 ° C. with good stirring in water. Subsequently, the obtained Nd-substituted faujasite X was taken out, treated with a saturated ammonium chloride solution for 4 hours, and Nd ⁺³ was coordinated to 9 SI sites. After drying the faujasite X, the faujasite X is uniformly mixed at a ratio of 4.59 g, 9.61 g, 21.27 g, and 35.71 g with respect to 100 g of silica powder, and sintered at 1750 ° C. A transparent silica glass was prepared. The doped amounts of Nd in the silica glass were 0.5 wt%, 1 wt%, 2.0 wt% and 3.0 wt%, respectively. When the fluorescence spectrum intensity of silica glass having a Nd doping amount of 1 wt% was measured, the relative fluorescence spectrum intensity with respect to the excitation light of 1063 nm was 9.38 [a. u. ]Met. Further, when the lifetime of the Nd-doped silica glass was measured, it was 400 μs or more as shown in FIG.
[0018]
On the other hand, when the relative fluorescence spectrum intensity for the excitation light of 1063 nm was measured in the same manner as described above for silica glass doped with 1.2 wt% Nd by the melting method, 0.668 [a. u. ]Met. Further, when the lifetime and relative fluorescence spectrum intensity of a phosphate glass generally used as a laser glass were measured, 300 μs and 5.81 [a. u. ]Met.
[0019]
Example 2
156 g of faujasite X and 477 g of NdCl ₃ were kept for 2 weeks while being refluxed at 100 ° C. with good stirring in water. Then, Nd-substituted faujasite X was taken out and treated with saturated ammonium chloride solution for 4 hours. Tetra-ethyl orthosilicate (hereinafter referred to as TEOS) is mixed and stirred in an aqueous solution containing faujasite X coordinated with Nd ⁺³ at 9 sites in a ratio of TEOS: water: 1N hydrochloric acid = 208 g: 180 g: 1 g. Then, a mixture of 0.2 to 1.0 μm colloidal silica and Nd-fixed faujasite X was produced using a small amount of aqueous ammonia as a catalyst. Next, the mixture and TEOS were mixed and gelled, and then dried at 300 ° C. The dried product was further pre-baked at 1500 ° C., adjusted to a particle size of 50 to 250 μm, mixed with natural quartz powder and pulverized to synthesize silica glass by the Bernoulli method. The concentration of Nd is 0.2 wt%, and the fluorescence spectrum intensity is 1.11 [a. u. ]Met.
[0020]
Example 3
A silica glass doped with 3.0 wt% of Ce was prepared in the same manner as in Example 1 except that Ce was used instead of Nd in Example 1. The fluorescence spectrum intensity of the silica glass was as shown in FIG.
[0021]
【The invention's effect】
In the production method of the present invention, after the rare earth element stably fixed to the zeolite, was mixed with medium material, from where the firing, there is no association of the rare earth elements, composition rare earth element characteristics are sufficiently exhibited is obtained . The production method is an industrially advantageous production method because it is a simple method in which zeolite and rare earth elements are ion-exchanged and treated with an ammonium chloride solution as necessary.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing that zeolite X has a hexagonal prism structure (D6R).
FIG. 2 is a graph showing the fluorescence spectrum intensity of the Nd-doped silica glass of the present invention.
FIG. 3 is a graph showing the lifetime of the Nd-doped silica glass of the present invention.
FIG. 4 is a graph showing the fluorescence spectrum intensity of the Ce-doped silica glass of the present invention.

Claims (11)

A method for producing silica glass for lasers , comprising mixing and sintering a zeolite and a silica raw material in which a rare earth element is fixed at an SI site. The method for producing silica glass for laser according to claim 1, wherein 3 to 13 rare earth elements are fixed to the SI site of the zeolite. 9. The method for producing silica glass for laser according to claim 2, wherein nine rare earth elements are fixed to the SI site of the zeolite. Method for producing a silica glass for laser as claimed in any one of 3 claims 1 you wherein the zeolite is faujasite. 5. The silica glass for laser according to claim 1, wherein the zeolite to which the rare earth element is fixed is a zeolite obtained by heating a water-soluble compound of a rare earth element and zeolite in water. Production method. 6. The method for producing silica glass for laser according to claim 5, wherein the treatment is further carried out with an ammonia chloride solution after heating in water. The method for producing silica glass for laser according to any one of claims 1 to 6, wherein the rare earth element is any one of Nd, Ho, Tm, Er, or Ce. The glass raw material is a powder obtained by gelling a mixture of a silica sol obtained by hydrolyzing alkoxysilane and a zeolite in which a rare earth element is fixed at an SI site, dried at 100 to 400 ° C., pre-fired and pulverized. The method for producing silica glass for laser according to claim 1. The method for producing silica glass for laser according to claim 8, wherein the pre-baking temperature is 1400 to 1600 ° C. 2. The method for producing silica glass for laser according to claim 1, wherein the silica raw material has a particle size of 50 to 250 [mu] m. The method for producing a silica glass for laser according to claim 1, wherein the glass raw material is vitrified by the Bernoulli method.

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