JP2007269599A - Metal-ceramic complex, method for producing the same, electron injection type refractive index change element and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-ceramic complex suitable for an optical element. <P>SOLUTION: The metal-ceramic complex comprises a first oxide phase (1) containing one component selected from SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>, Al<SB>2</SB>O<SB>3</SB>, TiO<SB>2</SB>, ZrO<SB>2</SB>, Na<SB>2</SB>O, CaO and SrO, metal particles (2) formed at the grain boundaries of the first oxide phase and containing one metal selected from Au, Ag, Cu, Pt, Pb and Pd, and a second oxide phase (3) formed at the grain boundaries of the first oxide phase (1) and containing ZnO, In<SB>2</SB>O<SB>3</SB>or one component selected from SiO<SB>2</SB>, B<SB>2</SB>O<SB>3</SB>, Al<SB>2</SB>O<SB>3</SB>, TiO<SB>2</SB>, ZrO<SB>2</SB>, Na<SB>2</SB>O, CaO and SrO and different from the component of the first oxide phase (1) and the same metal as the metal particles (2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite of metal and ceramic, an electron injection type refractive index changing element, and a method of manufacturing the same, and more particularly to a composite of metal and ceramic used for an optical element.

  Quantum dots—so-called nanoparticles exhibit physical properties that differ from bulk materials due to their “size effects”. Therefore, new physical properties are expected in the fields of optics, magnetism, electrons, catalysts and the like. In the field of electronic devices, the expression of the “Coulomb staircase” due to the “Coulomb brocade phenomenon” has recently been observed using self-organized gold nanoparticles that can be regarded as “quantum dots” with a diameter of 2 nm or less ( For example, refer nonpatent literature 1).

In addition, a glass in which semiconductor or metal nanoparticles are dispersed using hydrolysis of a gel film is also expected to have a large third-order nonlinear optical effect (see, for example, Patent Document 1). In particular, nanocomposite films in which Au particles are dispersed in SiO ₂ matrix have excellent characteristics such as simple recording head structure, resistance to mechanical damage, and higher recording speed as near-field recording materials. It is expected (see, for example, Non-Patent Document 2).

Further, there is an example in which an electron orbital is changed by injecting electrons into the quantum dots, and the refractive index of the composite element is arbitrarily changed. (For example, patent document 2).
Advanced Power Technol. 16 (2), 137-144 (2005) Proceedings of SPIE vol.5646 (2005) 555-562 JP-A-61-156007 JP 2005-156922 A

  These various characteristics are strongly influenced by the size of the nanoparticle which is a quantum dot. In particular, in a nanocomposite called a quantum dot, it is preferable to make the diameter uniform to several nm, preferably 2 nm or less. However, it is very difficult to align the quantum dot dimensions to a few nanometers or less.

  In addition, it is not easy to inject the same charge into all the quantum dots dispersed in the insulator matrix due to Coulomb repulsion. When a high voltage is applied to the device to forcefully inject electrons using a potential difference, the device itself may be destroyed.

  The present invention relates to a metal-ceramic composite comprising a large number of small-diameter quantum dots in a ceramic composite that can be regarded as an insulator, an electron injection type refractive index change element using the same, and a method of manufacturing the same.

The first aspect of the present invention is an oxide first phase containing at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO. And metal particles containing at least one metal selected from Au, Ag, Cu, Pt, Pb and Pd formed at the grain boundaries of the oxide first phase, and the grain boundaries of the oxide first phase SiO ₂ , B ₂ O ₃ , Al ₂ , which is a second phase of the oxide formed on the metal and is different from the metal of the same type as the metal particles, and ZnO, In ₂ O ₃ or the component of the first phase of the oxide. Provided is a metal-ceramic composite comprising an oxide second phase comprising at least one material selected from O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO.

  Such a composite of metal and ceramic can be used for a refractive index changing element that utilizes a change in refractive index caused by electron injection into metal particles. In addition, it can be used for a nonlinear waveguide circuit, an optical switch, a limiter, an optical logic element, or the like.

The second of the present invention is a first material containing at least one component selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO; SiO ₂ , B ₂ O different from ZnO, In ₂ O ₃ or the first material, and a second material containing at least one metal selected from Au, Ag, Cu, Pt, Pb and Pd ₃ , a step of producing a gel film using a third material containing at least one selected from Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO; A metal / ceramic composite comprising a step of heat-treating in an inert atmosphere to precipitate the second material and the third material at grain boundaries of the first material, and a step of oxidizing the third material A method for manufacturing a body is provided.

According to a third aspect of the present invention, an oxide first phase composed of at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Na ₂ O, CaO and SrO, and an oxide first phase Metal particles containing at least one metal selected from Au, Pt, Ag, Cu, Pu and Pb formed at the grain boundaries, and ZnO, TiO ₂ formed at the grain boundaries of the oxide first phase, and Provided is a metal / ceramic composite comprising an oxide second phase comprising at least one material selected from WO ₃ .

According to a fourth aspect of the present invention, there is provided an oxide first phase composed of at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Na ₂ O, CaO and SrO, and an oxide first phase. Metal particles containing at least one metal selected from Au, Pt, Ag, Cu, Pu and Pb formed at the grain boundaries, and ZnO, TiO ₂ formed at the grain boundaries of the oxide first phase, and A metal / ceramic composite comprising an oxide second phase containing at least one material selected from WO _{3 is} subjected to a treatment in which any one of electric field application, heat treatment, or light irradiation, or a combination thereof is combined. Provided is a method for manufacturing an electron injection type refractive index changing element.

  According to the composite of metal and ceramic of the present invention, it can be expected that a remarkable size effect (“so-called quantum size effect”) is realized by the presence of minute metal particles in the oxide first phase. In addition, according to the method for producing a composite of metal and ceramic according to the present invention, the first metal particle containing fine metal particles and the same metal material at the grain boundary of the oxide matrix (first phase). A third phase composed of an oxide different from the phase is formed, and a composite of metal and ceramic integrated by the three can be provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to the structure which is common throughout embodiment and an Example, and the overlapping description is abbreviate | omitted. Each drawing to be referred to is a schematic diagram for promoting explanation and understanding of the invention. For convenience of drawing display, the shape, dimensions, dimensional ratio, and the like are different from the actual method. The contents of the following description and the drawings are not intended to exclude any appropriate changes.

(First embodiment)
A composite of metal and ceramic according to a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a cross section of a composite of metal and ceramic according to the present embodiment.

  The composite of metal and ceramic according to the present embodiment includes an oxide first phase (parent phase) 1, metal particles 2, and an oxide second phase 3. As can be seen from FIG. 1, the metal particles and the oxide second phase are present at the grain boundaries of the oxide first phase.

The first oxide phase includes at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO. Since these materials are transparent to at least visible light, they are suitable when the metal-ceramic composite of this embodiment is used as an optical material. The first oxide oxide phase is generally amorphous. Also in this embodiment, amorphous can be used.

The oxide first phase is preferably SiO ₂ gel or glass. This is because these materials have the lowest attenuation rate as used in optical fibers, and can be obtained at low cost as metal alkoxides in the production of a composite of metal and ceramic.

  The metal particles include at least one metal selected from Au, Ag, Cu, Pt, Pb, and Pd. These metals are suitable as quantum dots that are easy for electrons to enter. Among them, so-called “noble” metals that are difficult to oxidize or materials that can be easily reduced even when oxidized (Au, Ag, Pt, etc.) are desirable.

  As the metal particles, Au is preferable. This is because Au is a noble metal that is most difficult to oxidize after Pt and has a characteristic that particles are less likely to aggregate due to a relatively high melting point.

The metal particles may be amorphous or crystalline.

  The average diameter of the metal particles is preferably set to several nm, preferably 2 nm or less.

The oxide second phase is selected from ZnO, In ₂ O ₃ and SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO, and SrO different from the first phase. At least one material. The oxide second phase further contains the same metal material as that of the metal particles 2. The metal material in the oxide second phase is finely precipitated or dissolved in the oxide of the second phase.

  The oxide second phase is desirably transparent to at least visible light in consideration of application to an optical material of a composite of metal and ceramic. That is, considering light scattering, even if the oxide phase 3 is slightly colored, if the size is 100 nm or less, no scattering occurs for visible light.

  A composite of metal and ceramic made of the above materials functions as an inorganic material.

  When Au is used for the metal particles 2, it is desirable to use ZnO for the second oxide phase. This is because Zn has a wide solid solubility limit with respect to Au, ZnO which is an oxide can also dissolve Au to some extent, and the like.

In the composite of metal and ceramic according to the present embodiment, the presence of the metal particles and the oxide second phase containing the same metal as the metal particles at the grain boundary of the oxide first phase allows the quantum dot ( It is possible to provide a composite in which (metal particles) are integrated with transparent ceramics. For example, in the SiO ₂ / Au / ZnO system, a composite in which very fine quantum dots of 2 nm or less are dispersed in an insulator can be formed.

  Such a transparent metal / ceramic composite can be used, for example, as a refractive index changing element. The refractive index changing element can inject electrons into quantum dots made of metal by external electric field or light irradiation, and can realize an electron injection type refractive index changing element exhibiting a giant refractive index exceeding 1%. .

(Second Embodiment)
In the second embodiment of the present invention, a method for producing a composite of metal and ceramic will be described.

  Starting materials for transparent ceramic matrices include metal alkoxides, metal acetylacetonates, acetates, carboxylates such as oxalates, metal inorganic compounds such as nitrates, chlorides and oxychlorides, and particulate oxides. Can be mentioned.

When a metal alkoxide represented by the general formula of M (OR) _n is used as a starting material,
M is a single element or multiple elements of Si, B, Al, Ti, Zr, Na, Ca, and Sr, R is an alkyl group such as a methyl group, an ethyl group, and a propyl group, and n is a metal The oxidation number of the element. A part of OR may be R.

  Such a metal alkoxide is dissolved in an alcohol such as methanol or ethanol to obtain a mixed solution. Since water is required for hydrolysis of the metal alkoxide, it is necessary to add water. Acids such as hydrochloric acid, sulfuric acid, nitric acid and acetic acid and alkalis such as ammonia are added as a catalyst for hydrolysis. When the film is easily broken by shrinkage, a drying control agent such as formamide or dimethylformamide is added.

The second phase includes at least one metal selected from Au, Ag, Cu, Pt, Pb and Pd. In addition, the third phase is composed of ZnO, In ₂ O ₃ or SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and different from the components of the oxide first phase. And at least one material selected from SrO.

The starting materials for the second and third phases are preferably organic solutions of metal salts such as chlorides, nitrates and acetates. If the metal salt is water-soluble, an aqueous solution may be used. A reducing agent such as formalin (HCHO) or sodium boron hydroxide (NaBH ₄ ) may be added to reduce the second and third phases to metal. The precursor prepared in this manner may be allowed to stand at room temperature to 150 ° C. for an appropriate time as necessary to proceed with hydrolysis and polycondensation reaction.

  In the case of forming a thin film, the obtained precursor is reacted for an appropriate time to adjust the viscosity, and then applied to the substrate by dip coating or spin coating. As the substrate, a semiconductor single crystal such as Si or GaAs, polycrystal, glass, or the like can be used, and a desired element can be formed by selecting an appropriate substrate. Application may be performed by a roller application method, a doctor blade method, a roller coating method, or the like.

By heating the precursor applied to the substrate, vitrification of the first phase gel and precipitation of the second and third phase materials at the grain boundaries of the first phase occur. The heating temperature is generally 200 ° C. or higher and 1200 ° C. or lower. In order to prevent coarsening due to aggregation of the second phase and the third phase, it is preferable to perform heat treatment at 200 ° C. or more and 500 ° C. or less. In order to prevent oxidation of the second phase and the third phase, it is performed in an inert atmosphere such as Ar, N ₂ or the like. If the second phase and the third phase are not oxidized, heat treatment may be performed in the atmosphere.

  Subsequently, heat treatment for homogeneously dissolving the second phase into the third phase is performed in an inert atmosphere. By this heat treatment, the second phase can be made into metal particles precipitated at the grain boundaries of the oxide first phase. Select the heat treatment temperature and time so that the second phase has the desired diameter. Depending on the material system, the heat treatment temperature may be higher than the precursor heating in the previous step.

  Further, oxidation is performed to oxidize the third phase to obtain a transparent material suitable for the optical material. By this oxidation, an oxide second phase can be formed. This oxidation may be performed in the air, but may be performed by controlling the oxygen partial pressure according to the necessity of the material system to be used. Depending on the material system, the heat treatment temperature may be higher than that in the previous step.

  The above is an example in which the composite of metal and ceramic according to the first embodiment is created by a sol-gel method, but the composite of metal and ceramic of the first embodiment is obtained by sputtering or ion plating, Can be manufactured.

(Third embodiment)
In the present embodiment, a composite of metal and ceramic capable of injecting charges into metal quantum dots without applying a high voltage to the element will be described.

FIG. 2 is a schematic cross-sectional view of the composite of metal and ceramic according to the present embodiment. The oxide first phase 1 (transparent ceramic matrix) made of at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Na ₂ O, CaO and SrO is mixed with Au, Pt, Ag Metal particles 2 (inorganic quantum dots) made of at least one metal selected from Cu, Pu, Pb, and oxide second made of at least one component selected from ZnO, TiO ₂ and WO ₃ This is a composite of metal and ceramic in which phase 3 (charge generation material) is dispersed. The inorganic particle dots 2 and the charge generation material 3 are formed as close as possible at the grain boundary of the transparent ceramic matrix. This is to facilitate the transfer of careers.

  The transparent ceramic matrix is desirably transparent at least to visible light. It is desirable for the matrix to be transparent as a final form for use as an optical material. In addition, it is preferable that the transparent ceramic matrix is an insulator because electrons injected into the quantum dots remain in the quantum dots.

  The diameter of the quantum dot is desirably about 2 nm or less. This is because the metal-ceramic composite of the present embodiment uses physical phenomena that are manifested by injecting electrons into the quantum dots and changing their energy levels. When there are too many electrons, the influence of charge injection is relatively low, and the expected physical phenomenon is not clearly expressed.

As the charge generation material, any material that can generate carriers by irradiating light can be used. As such a material, it is desirable to use particles made of at least one material selected from ZnO, TiO ₂ and WO ₃ . In addition, Se and Se alloys (CdSe, CdSSe, AsSe), inorganic optical semiconductors such as amorphous silicon, and the like are also included. These charge generation materials may be used alone or in combination of two or more. In order not to cause scattering or the like, the diameter is desirably 50 nm or less.

  When the composite of metal and ceramic is irradiated with light, carriers are generated in the charge generating material 3. The generated carriers move to the quantum dots 2 made of metal. Thus, it is possible to inject carriers into almost all quantum dots in a metal-ceramic composite without applying a high potential.

  As a method of manufacturing the composite of metal and ceramic according to this embodiment, a vacuum deposition method, a sputtering method, a CVD method, or the like can be used. In order to transfer and receive carriers smoothly, it is preferable that the quantum dots and the charge generating material are arranged adjacent to each other. For that purpose, the so-called sol-gel method is the most suitable production method.

(Fourth embodiment)
In the present embodiment, a method of manufacturing an electron injection type refractive index change element that enables smooth carrier injection by performing a detrapping process on the metal-ceramic composite according to the third embodiment will be described.

  When the composite of metal and ceramic according to the third embodiment is produced by the sol-gel method, chemical reactions such as matrix polymerization and decomposition of raw materials for forming quantum dots and charge generation materials are performed. In order to proceed, heat treatment is essential. It was confirmed that this heat treatment causes a phenomenon that thermal carriers are trapped in a plurality of level traps. In this case, a plurality of traps that cannot be controlled occur, such as a current flowing even if the voltage is held at 0V. For this reason, it becomes impossible to perform uniform carrier injection into the quantum dots by light excitation as described above. Therefore, an activation process is required to enable smooth carrier injection into the quantum dots. For initialization, the metal-ceramic composite produced by heat treatment is detrapped as completely as possible. Specifically, an electric field, heat treatment, or light is removed from the metal / ceramic composite alone or in combination to perform a detrapping process.

  Starting materials for transparent ceramic matrices include metal alkoxides, metal acetylacetonates, acetates, carboxylates such as oxalates, metal inorganic compounds such as nitrates, chlorides and oxychlorides, and particulate oxides. Can be mentioned.

  The metal alkoxide is represented by the general formula M (OR) n (M = Si, B, Al, Ti, Zr, Na, Ca, and Sr, a single element or a plurality of elements). This metal alkoxide can most easily form a polymer composed of a metal-oxygen bond. M is a metal element and may be single or bimetallic. R is an alkyl group such as a methyl group, an ethyl group, or a propyl group, and n is the oxidation number of the metal element. A part of OR may be R.

  Hereinafter, a method for producing a composite of metal and ceramic using a metal alkoxide and an electron injection type refractive index changing element will be described.

  A metal alkoxide is dissolved in an organic solvent such as methanol or ethanol to obtain a mixed solution. In order to dissolve the above metal compounds other than the metal alkoxide, ethylene glycol, ethylene oxide, triethanolamine, xylene and the like are also used.

  Water is required for hydrolysis of the metal alkoxide. When the starting material of the quantum dot and the charge generation material is not an aqueous solution system, it is necessary to add water separately. An acid such as hydrochloric acid, sulfuric acid, nitric acid or acetic acid or an alkali such as ammonia may be added as a catalyst for hydrolysis. When the film is easily broken by shrinkage, a drying control agent such as formamide or dimethylformamide is added.

  The starting material for the quantum dots and the charge generating material is preferably a solution system in which a metal salt such as a chloride, nitrate or acetate is dissolved in an organic solvent. If the metal salt is water-soluble, an aqueous solution system may be used. This is because the quantum dots and the charge generating material are preferentially precipitated not at the matrix but at the grain boundaries using the compatibility. In order to reduce the quantum dots to metal, a reducing agent such as formalin (HCHO) or sodium boron hydroxide (NaBH4) may be added.

  The precursor solution thus prepared is maintained at room temperature to 150 ° C. for an appropriate time as necessary, and a chemical reaction such as hydrolysis and polycondensation reaction proceeds.

  In the case of forming a composite film of metal and ceramic, after reacting for an appropriate time to adjust the viscosity, the film is applied to a substrate serving as a support by dip coating or spin coating. In addition, a roller coating method, a doctor blade method, a roller coating method, or the like may be used.

  As the substrate, a semiconductor single crystal such as Si or GaAs, polycrystal, glass, or the like can be used, and a desired element can be formed by selecting an appropriate substrate. The electrode is prepared on a surface that can be easily used as an element, such as an electrode surface as a support, a side surface of a composite of metal and ceramic, or a facing surface of the support. At this time, it is necessary to satisfy a geometrical condition so that light irradiation to the metal-ceramic composite can be reliably performed.

By heating the precursor applied to the substrate, vitrification of the gel as a matrix and precipitation of the quantum dots and the charge generating material on the crystal grain boundaries occur. The heat treatment is generally performed at 200 ° C. to 1200 ° C., but it is preferable to perform the heat treatment at 500 ° C. or lower in order to prevent coarsening due to aggregation of the quantum dots and the charge generating material. The heat treatment is performed in an inert atmosphere such as Ar, N ₂ or the like as necessary, but is usually in the air.

  Although the preparation example by the sol-gel method has been described above, the method is not limited as long as the transparent metal-ceramic composite described in the third embodiment can be manufactured.

  The composite of metal and ceramic produced in this manner is subjected to an initialization process that is a detrapping process before light irradiation for generating photocarriers. This treatment is performed by (1) electric field, (2) heat treatment, and (3) light irradiation alone or in combination. Such processing is performed until the current value becomes close to 0A.

  For example, heating is performed to a temperature lower than the firing temperature while applying an electric field, and the temperature is maintained as necessary, until the current has a low value and there is no change. Alternatively, light is applied to the composite of metal and ceramic until the current is low and there is no change. Alternatively, a positive or negative charge is dropped on the surface of the composite of metal and ceramic by corona charge to form an external electric field, and the temperature is raised from the lower part of the sample, thereby enabling efficient initialization.

  By irradiating the composite of metal and ceramic initialized as described above with light, carriers are generated in the charge generation material, and charge can be uniformly injected into adjacent quantum dots.

  Thus, the composite of the metal and ceramic into which the charge is injected can be used as a refractive index changing element. By injecting charges into the quantum dots, it is possible to obtain a refractive index changing element exhibiting a huge refractive index exceeding 1%.

Example 1
Examples according to the first and second embodiments of the present invention will be described.

Ethanol, water, dimethylformamide as a drying control agent, and hydrochloric acid as a catalyst were added to tetraethoxysilane (hereinafter referred to as TEOS), which is a raw material for the transparent matrix that is the first phase, and mixed at room temperature for 4 hours. Next, a solution in which HAuCl ₄ · 4H ₂ O was dissolved in ethanol, a solution in which ZnCl ₂ was dissolved in ethanol, and a reducing agent formalin were added and mixed at room temperature for 30 minutes. The added amounts of Au and Zn were finally set to Au: Zn = 1: 4 (mol ratio). The Au amount was finally set to 0.5 vol%. As a comparative material, a mixed solution having the same composition was prepared without adding ZnCl ₂ .

The mixed solution and the comparative material mixed solution were applied onto a 1 mm thick SiO ₂ substrate with a spin coater. The application condition was 1000 rpm-30 s. Subsequently, the sample was heat-treated. A horizontal electric furnace in which Ar was flowed at 2 l / min. Was maintained at 300 ° C., and the sample placed on a quartz boat was inserted therein. After holding the sample at 300 ° C. for 30 minutes, the flow gas was switched from Ar to Air. The air flow rate was 2 l / min. After maintaining for 15 minutes in this state, the sample was removed from the electric furnace. The same heat treatment was performed on the comparative material.

  After the sample had cooled to room temperature, spectrophotometric analysis was performed. The results are shown in FIG. The result of the comparative material is also shown. In the comparative material, as indicated by an arrow, an absorption peak due to surface plasmon was observed at around 530 nm, but such a peak was not observed in the sample of this example. It is said that the absorption due to surface plasmons near 530 / nm disappears when the Au diameter is 2 nm or less, and the above results are considered to indicate that fine Au particles could be formed.

Further, when the cross-sectional structure of the sample was also observed by TEM, it was confirmed that the structure schematically shown in FIG. 1 was formed. That is, gold particles having an average diameter of 1.5 nm and ZnO particles having an average diameter of 6 nm were observed adjacent to the amorphous SiO ₂ matrix.

(Example 2)
Examples according to the first and second embodiments of the present invention will be described.

Ti (OC ₃ H ₇ ) ₄ , iC ₃ H ₇ OH, water, and catalyst NH (CH ₂ CH ₂ OH) ₂ as raw materials for the transparent mother phase as the first phase were added and mixed at room temperature for 3 hours.

A solution in which AgNO ₃ was dissolved in iC ₃ H ₇ OH and a solution in which Zn (NO ₃ ) ₂ .6H ₂ O was dissolved in ethanol were added to this mixed solution, and mixed at room temperature for 30 minutes. The addition amount of Ag and Zn was finally set to Ag: Zn = 2: 3 (mol ratio). The Ag amount was finally set to 0.5 vol%. As a comparative material, a mixed solution having the same composition as that of the present invention was prepared except that Zn (NO ₃ ) ₂ .6H ₂ O was not added.

The mixed solution of this example and the comparative material mixed solution were applied on a SiO ₂ substrate having a thickness of 1 mm using a spin coater. The application condition was 1000 rpm-30 s. Subsequently, the sample was heat-treated. A horizontal electric furnace in which Ar was flowed at 2 l / min. Was maintained at 300 ° C., and the sample placed on a quartz boat was inserted therein. After holding the sample at 300 ° C. for 30 minutes, the flow gas was switched from Ar to Air. The air flow rate was 2 l / min. After maintaining for 15 minutes in this state, the sample was removed from the electric furnace. The same heat treatment was performed on the comparative material.

  After the sample had cooled to room temperature, spectrophotometric analysis was performed. In the comparative material, an absorption peak due to surface plasmon was observed at 580 nm, but such a peak was not observed in the sample of this example.

(Example 3)
Examples according to the third and fourth embodiments of the present invention will be described.

Ethanol, water, dimethylformamide as a drying control agent and hydrochloric acid as a catalyst were added to tetraethoxysilane (hereinafter referred to as TEOS) as a raw material for the transparent matrix, and mixed at room temperature for 4 hours. Subsequently, a solution in which HAuCl ₄ · 4H ₂ O was dissolved in ethanol and a solution in which ZnCl ₂ was dissolved in ethanol were added and mixed at room temperature for 30 minutes. The Au amount was finally set to 1 vol%. As a comparative material, a mixed solution having the same composition was prepared without adding ZnCl ₂ .

The mixed solution of this example and the comparative material mixed solution were applied on a SiO ₂ substrate having a thickness of 1 mm using a spin coater. The application condition was 1000 rpm-30 s. Subsequently, the sample was heat-treated. The horizontal electric furnace was maintained at 300 ° C., and the sample placed on a quartz boat was inserted. After holding the sample at 300 ° C. for 30 minutes, the sample was removed from the electric furnace. The same heat treatment was performed on the comparative material.

The cross-sectional structure of this sample was observed with TEM. It was confirmed that the structure schematically shown in FIG. 2 was formed. That is, a large number of Au particles having an average diameter of about 1.5 nm and a large number of ZnO particles having an average diameter of about 5 nm were observed adjacent to the amorphous SiO ₂ matrix.

Initialization was performed on the sample and comparative material of this example. Light having a wavelength of 700 nm was irradiated from a light source having an output of 10 mW / cm ² . And heat treatment was performed at 200 ° C. from the lower part of the sample. The initialization process was performed until there was no change in current.

Next, electrical measurements were performed with the configuration shown in FIG. When the sample of this example was irradiated with white light from a light source with an output of 10 mW / cm ² , a photocurrent of about 3 pA was generated, but the comparative material did not detect any current at all.

Example 4
Examples according to the third and fourth embodiments of the present invention will be described.

Al (OC ₃ H ₇ ) ₄ , iC ₃ H ₇ OH, and water as raw materials for the transparent matrix were added and mixed at room temperature for 2 hours. Then, a solution of AgNO ₃ dissolved in iC ₃ H ₇ OH and a 30% titanium (IV) sulfate solution were added and mixed at room temperature for 1 hour. The Ag amount was finally set to 3 vol%.

The mixed solution of this example was applied by a spin coater onto a 1 mm thick SiO ₂ substrate having an ITO electrode formed on the surface. Part of the solution was removed so that the electrode came out. Subsequently, the sample was fired. A horizontal atmospheric furnace was maintained at 400 ° C., and the sample placed on a quartz boat was inserted therein. After holding the sample at 400 ° C. for 30 minutes, the sample was removed from the electric furnace. Two samples were produced under the same conditions. Further, Au deposition was performed on the sample surface to form a facing electrode.

  Subsequently, the initialization process described in the fourth embodiment was performed on one sample. The configuration is shown in FIG. A voltage of 100 V was applied for 3 hours, and the treatment was continued until no change was observed in the current value. The other sample was not initialized.

Subsequently, a charge injection test was performed with the configuration shown in FIG. In the sample of this example, no current was detected when no light was irradiated, and a current of about 5 pA was detected for the first time when white light was irradiated from a light source with an output of 10 mW / cm ² . On the other hand, in the comparative material that was not subjected to the initialization process, a current on the order of sub-μA continued to flow without irradiating light.

(Example 5)
Ethanol, water, dimethylformamide as a drying control agent and hydrochloric acid as a catalyst were added to tetraethoxysilane (hereinafter referred to as TEOS) as a raw material for the transparent matrix, and mixed at room temperature for 4 hours. Subsequently, a solution in which HAuCl ₄ · 4H ₂ O was dissolved in ethanol and a solution in which ZnCl ₂ was dissolved in ethanol were added and mixed at room temperature for 30 minutes. The amount of Au was finally set to 3 vol%. As a comparative material, a mixed solution having the same composition as in this example was prepared except that HAuCl ₄ .4H ₂ O was not added.

The mixed solution of this example and the comparative material mixed solution were applied on a SiO ₂ substrate having a thickness of 1 mm using a spin coater. Subsequently, the sample was heat-treated. The horizontal electric furnace was maintained at 300 ° C., and the sample placed on a quartz boat was inserted. After holding the sample at 300 ° C. for 30 minutes, the sample was removed from the electric furnace. The same heat treatment was performed on the comparative material.

  Initialization with an electric field was first performed on this example and the comparative material. An external electric field was formed on the sample surface by applying -6kV with a corona charger. And heat treatment was performed at 200 ° C. from the lower part of the sample. The initialization process was performed until there was no change in the current value.

Examples and comparative materials were irradiated with white light using a light source with an output of 10 mW / cm ² . Subsequently, the thermal stimulation current measurement was performed in the range of RT to 200 ° C. with the configuration shown in FIG. In the sample of the present invention containing Au quantum dots, a current of about 7 pA at the maximum was detected, but the current was not detected at all in the comparative material.

1 is a schematic cross-sectional view of a ceramic composite according to a first embodiment of the present invention. Sectional schematic diagram of the ceramic composite body concerning the 3rd Embodiment of this invention. Absorbance analysis results in Example 1 according to the first and second embodiments of the present invention Initialization process schematic diagram of Example 4 according to the third and fourth embodiments of the present invention Schematic of electrical measurement of Example 4 according to the second, third and fourth embodiments of the present invention

Explanation of symbols

1. SiO ₂ (oxide first phase)
2. 2. Au particles ZnO (oxide second phase)

Claims (7)

A first oxide phase containing at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO;
Metal particles containing at least one metal selected from Au, Ag, Cu, Pt, Pb and Pd, formed at the grain boundaries of the oxide first phase;
A second oxide phase formed at a grain boundary of the first oxide phase, wherein the same kind of metal as the metal particles is different from ZnO, In ₂ O ₃ or a component of the first oxide phase. A metal and ceramic comprising an oxide second phase comprising at least one material selected from ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO Complex. _2. The metal-ceramic composite according to claim 1, wherein the first oxide phase is SiO ₂ gel or glass, the metal is Au, and the second oxide phase is ZnO containing Au. 3. The electron injection type refractive index changing element using a composite of metal and ceramic according to claim 1 or 2, wherein a change in refractive index due to electron injection into the metal particles is utilized. A first material containing at least one component selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Na ₂ O, CaO and SrO; and Au, Ag, Cu, Pt SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , TiO ₂ different from ZnO, In ₂ O ₃ or the first material, and a second material containing at least one metal selected from Pb, Pb and Pd Forming a gel film using a third material containing at least one selected from ZrO ₂ , Na ₂ O, CaO and SrO;
Heat-treating the gel film in an inert atmosphere, and precipitating the second material and the third material at grain boundaries of the first material;
A method for producing a composite of metal and ceramic, comprising the step of oxidizing the third material. An oxide first phase composed of at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Na ₂ O, CaO and SrO;
Metal particles containing at least one metal selected from Au, Pt, Ag, Cu, Pu and Pb formed at the grain boundary of the oxide first phase;
Metal and ceramic comprising at least one material selected from ZnO, TiO ₂ , WO ₃ , Se, Se alloy and amorphous Si formed at the grain boundary of the oxide first phase Complex. 6. The electron injection type refractive index change element using a composite of metal and ceramic according to claim 5, wherein a change in refractive index due to electron injection into the metal particles is utilized. An oxide first phase composed of at least one material selected from SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Na ₂ O, CaO and SrO, and a grain boundary of the oxide first phase; Metal particles containing at least one metal selected from Au, Pt, Ag, Cu, Pu and Pb, and at least one selected from ZnO, TiO ₂ and WO ₃ formed at the grain boundary of the oxide first phase. A composite of a metal and a ceramic having an oxide second phase containing one material, and any one of electric field application, heat treatment, and light irradiation, or a combination of electric field application, heat treatment, and light irradiation. Of manufacturing an electron injection type refractive index changing element.

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