JPH05150277A - Fine metal particle dispersed material and production thereof - Google Patents

Abstract

PURPOSE:To improve tertiary nonlinear optical characteristics by dispersing fine metal particles in glass produced by a sol-gel process or in a polymer matrix or dispersing and supporting the particles in the pores in a porous material. CONSTITUTION:Fine metal particles are dispersed in glass produced by a sol-gel process or in a polymer matrix or the particles are dispersed and supported in the pores in a porous material. The particles a preferably dispersed in the glass by alternately laminating glass layers produced by the sol-gel process and fine metal particle layers. The metal is preferably at least one among Au, Pt, Ag, Rh, Pd and Ir. The polymer is preferably at least one among polystyrene, polyethylene and an acrylonitrile-styrene copolymer. The porous material is preferably porous glass, zeolite or activated alumina.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal fine particle dispersion material used as a nonlinear optical material which forms the basis of an optical device utilizing the nonlinear optical effect, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, nonlinear optical materials have been considered for use as optical devices such as high-speed optical switches and harmonic generating elements. In particular, with respect to the nonlinear optical material using metal fine particles, semiconductor fine particles or an organic compound having nonlinear optical characteristics, which is the core of the material, attention has been paid to the development of higher performance materials or improved materials and manufacturing methods thereof.

As a conventional technique in this field, for example, Applied Physics A Vol. 47, page 347 (Ap.
pl. Phys. A, Vol.47, 347 1988), there is a method for producing fine glass particles dispersed by gold by the melting method.

This method is based on a melting and cooling method similar to the conventional method for producing filter-glass, in which gold dissolved in a glass matrix is further heat treated to be deposited as fine gold particles.

In addition, the journal of optical
Society of America B Volume 7 Page 790 (J.
Opt. Soc. Am.B, Vol.7, 790 1990), there is a method for producing a gold colloid.

In this method, a reducing agent is added to a 0.01% aqueous solution of chloroplatinic acid to produce colloidal gold.

[0007]

The method for producing a metal fine particle dispersed material of the above method has the following problems. (1) In the case of metal fine particle dispersed glass: In the melt cooling method,
10 ^-6 to 10 ^-5 due to the low solubility of metals in glass
The amount of metal dispersed can be increased only to about the volume%. Furthermore, in order to precipitate the metal dispersed in the glass as fine particles, it is necessary to perform heat treatment at a high temperature of 1000 ° C. or higher. Therefore, a material having low heat resistance cannot be used, and it takes time to cool, so that gold particles grow large during that time, and there is a problem that the characteristics are deteriorated as a nonlinear optical material. (2) Gold colloid solution: It is difficult to increase the concentration of gold colloid, and aggregation occurs at a concentration of 10 ^-6 % by volume or more. Further, even if a low-concentration colloidal solution is prepared, it lacks long-term stability, and the solution composition gradually changes or the particle size of the colloid increases with the passage of time.

The present invention provides a metal fine particle dispersed material which can disperse metal fine particles having a uniform particle size in a glass or a high molecular weight polymer matrix or a porous material at a high concentration, and which has large third-order nonlinear optical characteristics. It is intended to provide a manufacturing method.

[0009]

In order to solve the above problems, the metal fine particle dispersion material of the present invention is a glass prepared by a sol-gel method, or metal fine particles are dispersed in a polymer matrix, or The fine metal particles are dispersed and supported in the pores of the porous material. In the above structure, it is preferable to have a structure in which glass layers and metal fine particle layers produced by the sol-gel method are alternately laminated.

Further, in the above constitution, it is preferable that the fine metal particles are at least one metal selected from gold, platinum, silver, rhodium, palladium, or iridium. Further, in the above constitution, it is preferable that the high molecular polymer matrix is at least one selected from polystyrene, polyethylene and acrylonitrile-styrene copolymer.

In the above construction, it is preferable that the porous material is porous glass, zeolite or activated alumina. Next, the first method for producing a metal fine particle dispersed material according to the present invention is a method in which metal fine particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt are added to an organic polymer solution. It is composed by dispersing the metal colloid or metal fine particles protected by the organic polymer into the glass or polymer matrix prepared by the sol-gel method.

The second method for producing a metal fine particle dispersed material according to the present invention is a method in which metal fine particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt are used as an organic polymer. It is composed by dispersing in a solution to form a metal colloid or metal fine particles protected by the organic polymer, and supporting this in the pores of the porous material.

[0013]

In the metal fine particle dispersion material of the present invention, the metal fine particles are dispersed in the glass prepared by the sol-gel method or the polymer matrix, or the fine metal particles are dispersed and carried in the pores of the porous material. In a glass or high polymer matrix, or
It is possible to disperse metal fine particles having a uniform particle size in the pores of the porous material at a high concentration, and it is possible to realize a metal fine particle dispersed material having large third-order nonlinear optical characteristics.

Further, by adopting a preferred embodiment having a structure in which glass layers produced by the sol-gel method and metal fine particle layers are alternately laminated, even when the metal fine particles are dispersed at a high concentration, the glass Since the metal fine particles can be separated from each other by the matrix and the fine particles can be confined as they are, it is possible to prevent the fine metal particles from growing and increasing in particle diameter even when heat treatment is performed, and to obtain a metal having a uniform particle diameter. It is possible to provide a metal fine particle dispersed material in which fine particles are dispersed and which has excellent nonlinear optical characteristics.

In a preferred embodiment, the fine metal particles are at least one metal selected from gold, platinum, silver, rhodium, palladium, or iridium.
These noble metals can realize a metal fine particle dispersed material having third-order nonlinear optical characteristics larger than those of other metals.

Further, by adopting a preferred embodiment in which the high molecular polymer matrix is at least one selected from polystyrene, polyethylene and acrylonitrile-styrene copolymer, these high molecular polymers can be easily formed into a thin film. Since it can be molded and can be formed into a film-like material having a useful form as a nonlinear optical material, it becomes possible to realize a metal fine particle dispersed material having large third-order nonlinear optical characteristics.

Further, by adopting a preferred embodiment in which the porous material is porous glass, zeolite or activated alumina, these porous materials are optically transparent and the pore size is relatively uniform. Therefore, it is possible to provide a metal fine particle dispersed material having excellent nonlinear optical characteristics in which metal fine particles having a uniform particle size are dispersed.

Next, in the first method for producing a metal fine particle dispersed material of the present invention, metal fine particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt is used as an organic polymer. Since the metal colloid or metal fine particles protected by the organic polymer are dispersed in the solution and dispersed in the glass or the polymer matrix prepared by the sol-gel method, the metal fine particles are aggregated even in the raw material preparation stage. In addition, it is possible to uniformly disperse the metal fine particles at a high concentration without raising the temperature,
It is possible to easily obtain a metal fine particle dispersed material having a large third-order nonlinear optical characteristic.

In the second method for producing a metal fine particle dispersed material of the present invention, metal fine particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt are used as an organic polymer. As the metal colloid or metal fine particles protected by the organic polymer is dispersed in the solution and is supported in the pores of the porous material, there is no aggregation of the metal fine particles even at the raw material preparation stage, and the high temperature is maintained. It is possible to disperse the metal fine particles uniformly in a high concentration without performing the above, and it is possible to easily obtain a metal fine particle dispersed material having a large third-order nonlinear optical characteristic.

[0020]

The present invention will be described in more detail with reference to the following examples. In the present invention, the glass matrix produced by the sol-gel method is preferably SiO ₂ glass which is chemically stable and optically transparent in a wide wavelength range.

The sol-gel method is a method in which a sol-like lower metal alkoxide in which fine metal particles are dispersed is hydrolyzed to form a gel, which is then heated and baked to form a glass.

As the sol which becomes a matrix by gelation, one capable of forming an optically transparent gel is used. For example, typically, it is gelated and SiO ₂ or Al ₂ O is used.
A sol of ₃ is used, and SiO ₂ is particularly preferable.

Typical typical examples are silicon lower alkoxides such as silicon metoxide and etoxide, and aluminum lower alkoxides such as aluminum metoxide and etoxide. As a sol dispersion medium, water and / or Or methano
A lower alcohol such as alcohol or ethanol is usually used, and it is usually used in a partially hydrolyzed form by adding hydrochloric acid as a catalyst.

In the present invention, gelation of the sol containing fine metal particles is usually carried out at room temperature to 100 ° C. In addition, the firing temperature in the firing step of firing the sol after gelling is usually 300 to 800 ° C., and preferably after firing at 300 to 400 ° C. for removing organic substances in the matrix, metal fine particles It is preferable to perform firing at 360 to 800 ° C. for the purpose of causing the grain growth of the above.

The porous material used in the present invention is preferably, for example, porous glass, zeolite or activated alumina. The porous glass is preferably SiO ₂ glass which is chemically stable and optically transparent in a wide wavelength range. The average pore diameter of the porous glass is preferably 10 nm or less at which the surface plasma resonance of the metal fine particles is enhanced and the quantum size effect is remarkably observed. The lower limit is not particularly limited but is usually about 1 nm.

The zeolite used in the present invention is preferably an A, X or Y type zeolite which is artificially synthesized and has a controlled particle size. In order to support the metal fine particles in the pores of these porous materials, there is a method of immersing the porous material in a solution in which the metal fine particles are dispersed, and drying or firing.

Further, as the high molecular polymer (synthetic resin) which becomes the matrix, polystyrene, polyethylene or AS resin (acrylonitrile / styrene copolymer) which is particularly easy to form into a film is preferable. It is possible to use a polymer polymer having transparency and film forming property, such as polyester, polyamide, polymethylmethacrylate and the like.
A solvent may be used to disperse the fine metal particles in the polymer matrix, or a heat melting method may be used to disperse the metal at a temperature at which the polymer melts.

The fine metal particles to be dispersed in the present invention are preferably metals exhibiting non-linear optical characteristics based on surface plasma absorption or quantum size effect, such as gold, platinum, silver, rhodium, palladium, or iridium.

The size of these metal fine particles is preferably about 1 to 8 nm in average particle size. The amount of the fine metal particles dispersed in the matrix is preferably about 10 ⁻³ to 10 ⁻² % by volume.

In order to support the metal fine particles on the glass matrix or the polymer matrix prepared by the sol-gel method, the following two methods are preferably used. As the first method, metal fine particles obtained by mechanically crushing a metal lump or by applying a reducing agent to an aqueous solution of a metal salt were dispersed in an organic polymer solution to be protected by the organic polymer. A metal colloid or fine metal particles are dispersed in a glass or polymer matrix prepared by the sol-gel method.

As a second method, metal fine particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt are dispersed in an organic polymer solution to obtain the above-mentioned organic high-concentration. There is a method in which a metal colloid or metal fine particles protected by molecules are prepared and supported in the pores of the porous material.

To disperse the metal fine particles in an organic polymer solution to form a metal colloid or metal fine particles protected by the organic polymer, for example, a method of dispersing in a solution of polyvinyl alcohol, polyvinyl pyrrolidone or the like can be mentioned.

Specific examples of the present invention will be described below. Example 1 Gold particles having an average particle size of 5 nm prepared by mechanically crushing a gold ingot into a sol having the composition shown in Table 1 were added so as to be 10 ⁻³ % by volume, and then stirred at room temperature and further 60 ° C. After drying at the temperature of 50 hours, the mixture was gelated and baked at 600 ° C. The absorption spectrum of the gold particle-dispersed SiO ₂ glass prepared in this way was 530 nm.
A peak due to the surface plasma absorption was observed in. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 7 × 10 ⁻⁷ esu.

In the above process, platinum, silver, instead of gold,
Even if rhodium, palladium, or iridium was used, the SiO ₂ glass in which the respective metal fine particles were dispersed could be produced. The third-order nonlinear optical susceptibility of each was in the range of 10 ^-8 to 10 ^-7 esu.

[0035]

[Table 1]

Example 2 Gold fine particles were dispersed in an AS resin having a thickness of 0.2 mm by the method described below. After adding gold fine particles having an average particle size of 5 nm to an acetone solution of AS resin by mechanically pulverizing the gold ingots so as to be 10 ⁻³ % by volume, the gold fine particles were dried at a temperature of about 80 ° C. A dispersed AS resin was prepared. In the absorption spectrum of this material, a peak due to surface plasma absorption was observed at 528 nm. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 6 × 10 ⁻⁷ esu.

In the above process, platinum, silver, instead of gold,
Even if rhodium, palladium, or iridium was used, the AS resin in which the respective metal fine particles were dispersed could be produced. Also, each third-order nonlinear optical susceptibility is
It was in the range of 10 ^-8 to 10 ^-7 esu. Further, even if polystyrene, polyethylene, polypropylene, polyester, polyamide, or polymethylmethacrylate is used as the matrix high-molecular polymer, a gold fine particle dispersed film having the same characteristics as the AS resin can be produced.

Example 3 A platinum colloid prepared by the following method was added to a sol having the composition shown in Table 1 of Example 1 so that the concentration was 10 ⁻³ % by volume, followed by stirring at room temperature and further at a temperature of 60 ° C. After drying for 50 hours, it was gelled and baked at 600 ° C. Platinum colloid was prepared by adding chloroplatinic acid aqueous solution (1 g-Pt / l) to distilled water and boiling.
An aqueous solution of sodium citrate (1 wt%) was added and the mixture was boiled, and then polyvinyl alcohol was added. In addition to sodium citrate, hydrogen, hydrazine, sodium borohydride, etc. could be used for the reduction of metal ions to metals. Further, it was possible to stabilize the colloid by protecting the platinum colloid with polyvinylpyrrolidone in addition to polyvinyl alcohol. In the absorption spectrum of the gold fine particle-dispersed SiO ₂ glass having an average particle diameter of 4 nm thus produced, a peak due to surface plasma absorption was observed at 525 nm. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 3 × 10 ⁻⁷ esu.

Even if gold or an alloy of gold and platinum was used instead of gold in the above process, a SiO ₂ glass in which the respective metal fine particles were dispersed could be produced. Also,
Each third-order nonlinear optical susceptibility was in the range of 10 ^-8 to 10 ^-7 esu.

Example 4 Thickness of 0.2 mm in which fine gold particles were dispersed by the following method
AS resin was manufactured.

A platinum colloid prepared by the following method was added to the AS resin emulsion in an amount of 10 ^-3 % by volume, and dried at a temperature of about 80 ° C. to prepare an AS resin in which fine gold particles were dispersed. The platinum colloid was prepared by adding an aqueous solution of chloroplatinic acid (1 g-Pt / l) to distilled water and boiling, then adding an aqueous solution of sodium citrate (1 wt%) and boiling, and further adding polyvinyl alcohol. In addition to sodium citrate, hydrogen, hydrazine, sodium borohydride, etc. could be used for the reduction of metal ions to metals. Further, it was possible to stabilize the colloid by protecting the platinum colloid with polyvinylpyrrolidone in addition to polyvinyl alcohol. In the absorption spectrum of the gold fine particle-dispersed AS resin having an average particle diameter of 4 nm thus produced, a peak due to surface plasma absorption was observed at 527 nm. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 3 × 10 ⁻⁷ esu.

Even when gold or an alloy of gold and platinum was used in place of gold in the above process, the AS resin in which the respective metal fine particles were dispersed could be produced. The third-order nonlinear optical susceptibility of each was in the range of 10 ^-8 to 10 ^-7 esu.

Example 5 A quartz substrate was immersed in a sol having the composition shown in Table 1 of Example,
It was dried at a temperature of 60 ° C. for 50 hours, gelled, and then baked at 600 ° C. to form a SiO ₂ thin film having a thickness of 0.3 μm. Further, the substrate on which such a film is formed is immersed in a solution containing 10 ^-2 % by volume of gold fine particles with an average particle size of 5 nm prepared by mechanically crushing a gold ingot, and then at a temperature of 60 ° C for 1 hour. It was dried to form a gold fine particle layer. By repeating the above steps 10 times, a metal fine particle dispersed material having a structure in which gold fine particle layers and glass layers were alternately laminated was formed. The absorption spectrum of the gold fine particle dispersed material thus prepared is 528
A peak due to surface plasma absorption was observed at nm. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 5 × 10 ⁻⁷ esu.

In the above process, platinum, silver, instead of gold,
Even when rhodium, palladium, or iridium was used, it was possible to prepare a metal fine particle dispersed material having a structure in which the metal fine particle layers and the glass layers were alternately laminated. Also, each third-order nonlinear optical susceptibility is 10 ^-8 ~
It was in the range of 10 ^-7 esu.

Example 6 Porous glass having a thickness of 0.5 mm (average pore diameter 4 nm, specific surface area)
200 m ² / g) (hereinafter porous glass is abbreviated as PVG)
The fine gold particles were supported by the method described below. Ten gold particles with an average particle size of 3 nm prepared by mechanically crushing a gold ingot were used.
-PVG is immersed in a solution containing ² % by volume and then at a temperature of 60 ° C.
It was dried for 1 hour to support the fine gold particles. By repeating the above process 5 times, PVG with 0.1 wt% of gold particles was prepared. A peak due to surface plasma absorption was observed at 531 nm in the absorption spectrum of the PVG loaded with gold particles thus prepared. Furthermore, the third-order nonlinear optical susceptibility by the front incidence type degenerate four-wave mixing method was 3 × 10 ⁻⁷ esu.

In the above process, platinum, silver, instead of gold,
It was also possible to produce PVGs bearing metal fine particles using rhodium, palladium, or iridium.
In addition, each third-order nonlinear optical susceptibility is 10 ^-8 to 10 ^-7.
was in the esu range.

Further, a material having almost the same characteristics as the porous glass could be obtained by using zeolite or activated alumina in addition to the porous glass. Example 7 An optical bistable element was produced using the material shown in Example 1. Laser light with a wavelength of 530 nm is spotted on this device with a spot diameter of 5
When the incident light was incident at .mu.m and the relationship between the intensity of the incident light and the intensity of the emitted light was measured at room temperature (25.degree. C.), a bistable characteristic was shown.

As described above, according to the metal fine particle dispersion material and the method for producing the same of the present invention, the metal fine particles having a uniform particle size can be dispersed at a high concentration in the glass or the polymer matrix by the sol-gel method, or the metal fine particles can be dispersed. Can be supported on a porous material at a high concentration, and an optical bistable element or the like that can be used as a high-speed optical switch can be manufactured.

[0049]

INDUSTRIAL APPLICABILITY The metal fine particle dispersion material of the present invention can disperse metal fine particles having a uniform particle size in a glass or a polymer matrix or in the pores of a porous material at a high concentration. Therefore, it is possible to realize a metal fine particle dispersed material having a large third-order nonlinear optical characteristic.

Further, by adopting a preferable embodiment having a structure in which glass layers and metal fine particle layers produced by the sol-gel method are alternately laminated, even if the metal fine particles are dispersed at a high concentration, the glass The matrix can separate the metal particles from each other and confine them as they are, thus preventing the growth of the metal particles and dispersing the metal particles having a uniform particle size to obtain a metal particle dispersion having excellent nonlinear optical characteristics. Material can be provided.

By providing a preferable mode in which the metal fine particles are at least one metal selected from gold, platinum, silver, rhodium, palladium, or iridium,
These noble metals can realize a metal fine particle dispersed material having third-order nonlinear optical characteristics larger than those of other metals.

Further, by adopting a preferred embodiment in which the polymer matrix is at least one selected from polystyrene, polyethylene and acrylonitrile-styrene copolymer, it is possible to easily form a thin film into a film, and the nonlinear optical Since a film-like material having a form useful as a material can be obtained, it becomes possible to easily realize a metal fine particle dispersed material having a large third-order nonlinear optical characteristic.

Further, by adopting a preferable embodiment in which the porous material is porous glass, zeolite or activated alumina, a fine metal particle dispersion material having excellent non-linear optical characteristics in which fine metal particles having a uniform particle size are dispersed is provided. it can.

Further, according to the first method for producing a metal fine particle dispersed material of the present invention described above, the metal fine particles do not aggregate even in the raw material preparation step, and the metal is uniformly and uniformly at a high temperature. The fine particles can be dispersed, and a metal fine particle dispersed material having large third-order nonlinear optical characteristics can be easily obtained.

Further, according to the second method for producing a metal fine particle dispersion material of the present invention, the metal fine particles are not aggregated even in the raw material preparation stage, and the metal fine particles are uniformly formed at a high concentration without being heated to a high temperature. It is possible to disperse, and it is possible to easily obtain a metal fine particle dispersed material having a large third-order nonlinear optical characteristic.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Mikuro 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A fine metal particle dispersion material in which fine metal particles are dispersed in glass prepared by a sol-gel method or a polymer matrix, or fine metal particles are dispersed and carried in the pores of a porous material. .. 2. A metal fine particle dispersion material having a structure in which glass layers and metal fine particle layers produced by a sol-gel method are alternately laminated. 3. The fine metal particles are gold, platinum, silver, rhodium,
The metal fine particle dispersion material according to claim 1 or 2, which is at least one selected from palladium and iridium. 4. The metal fine particle dispersion material according to claim 1, wherein the high molecular polymer matrix is at least one selected from polystyrene, polyethylene, and an acrylonitrile-styrene copolymer. 5. The metal fine particle dispersion material according to claim 1, wherein the porous material is porous glass, zeolite or activated alumina. 6. A metal protected by the organic polymer by dispersing fine metal particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt in an organic polymer solution. A method for producing a metal fine particle dispersion material, which comprises colloidal or metal fine particles and dispersing the colloidal or metal fine particles in a glass or polymer matrix prepared by a sol-gel method. 7. A metal protected by the organic polymer by dispersing fine metal particles obtained by mechanically crushing a metal lump or by causing a reducing agent to act on an aqueous solution of a metal salt in an organic polymer solution. A method for producing a metal fine particle dispersed material, comprising colloid or metal fine particles, which are supported in pores of a porous material.