Locally crystallized glass and method for manufacturing locally crystallized glass

Abstract

To provide locally crystallized glass in which physical properties such as thermal properties and optical properties can be controlled. [Solution] A glass having a localized crystalline phase containing a metal dopant.

Description

[Technical Field]

[0001] This invention relates to locally crystallized glass and a method for producing locally crystallized glass. [Background technology]

[0002] Glass is a material with high chemical stability, light transmittance, and electrical insulation properties. Crystallized glass, which combines the properties of both glass and crystals, is known as a form of glass with added functionality.

[0003] As a conventional crystallized glass, Patent Document 1 describes one in which minute crystals are dispersed and precipitated inside amorphous glass by annealing. The crystallized glass of Patent Document 1 can be stabilized to have uniform physical properties by adjusting the annealing conditions using materials with a specific composition ratio, thereby ensuring that the size of the crystals precipitated inside the glass is uniform and that the crystals are uniformly dispersed and precipitated. As a result, it is possible to obtain crystallized glass that can be used as a glass-ceramic substrate for optical filters applied to optical communication systems. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-19659 (pages 3-5) [Overview of the project] [Problems that the invention aims to solve]

[0005] However, while the crystallized glass described in Patent Document 1 can be stably obtained with high homogeneity by adjusting the annealing conditions using materials with a specific composition ratio, the physical properties such as thermal and optical properties within the glass become uniform, making it impossible to arbitrarily control the physical properties within the glass. Through the inventors' research, it has become possible to arbitrarily control the physical properties within crystallized glass using a completely new method, and a technology that will serve as the foundation for imparting new functionality to crystallized glass has been established, which will be explained below.

[0006] This invention was made in view of these problems, and aims to provide a locally crystallized glass whose physical properties, such as thermal properties and optical properties, can be controlled. [Means for solving the problem]

[0007] The inventors of the present invention have been diligently investigating the above problem, and have found that a locally crystallized glass according to one aspect of the present invention is We discovered that by using a glass with a localized crystalline phase containing a metal dopant, it is possible to obtain a glass whose physical properties, such as thermal and optical properties, can be controlled by the distribution of the localized crystalline phase, and this led to the completion of the present invention.

[0008] The aforementioned glass may be soda-lime glass. According to this method, the distribution of the crystalline phase can be controlled with high precision.

[0009] In the aforementioned crystalline phase, needle-shaped crystals may be more abundantly distributed around the periphery than in the center. According to this method, the thermal properties can be improved by suppressing expansion around the crystalline phase.

[0010] The crystalline phase may contain at least one of CaMgSi2O6 and CaSiO3. According to this, mechanical strength can be increased.

[0011] The crystalline phase may contain more Ca and Mg and less Na than the amorphous phase. According to this, the heat resistance can be enhanced.

[0012] The crystallization range of the crystalline phase may be from 0.1 μm to 500 μm in diameter. According to this, physical properties such as thermal properties and optical properties can be controlled with high precision.

[0013] The metal dopant may be Mn. According to this, since the glass can be doped with a high concentration of the metal dopant, the degree of freedom in designing the crystalline phase can be increased.

[0014] A method for manufacturing locally crystallized glass according to another aspect of the present invention is a metal doping step of irradiating laser light from the glass side to the metal thin film, the metal powder or the metal foil of the glass on which the metal thin film, the metal powder or the metal foil is disposed to form metal spheres inside the glass, and separating metal fine particles from the metal spheres while moving the metal spheres; an annealing step of annealing the metal-doped glass obtained by the metal doping step; and includes these. According to this, by annealing the metal-doped glass locally doped with the metal dopant, only the metal-doped portion can be crystallized, so that a glass capable of controlling physical properties such as thermal properties and optical properties by the local crystalline phase distribution can be obtained.

[0015] The annealing treatment may be performed at a temperature equal to or higher than the glass transition point. According to this, crystallization of the metal-doped portion can be promoted.

[0016] The metal may be Mn. According to this, since the glass can be doped with a high concentration of the metal dopant, the degree of freedom in designing the crystalline phase can be increased.

Brief Description of Drawings

[0017] [Figure 1] This is a diagram showing an example of a metal sphere introduction device in an embodiment according to the present invention. [Figure 2] (a) is a scanning electron microscope (SEM) photograph showing a cross-section of the movement locus of the metal sphere, and (b) is an enlarged view of (a). [Figure 3] (a) is an SEM photograph showing sample 1 after annealing at 750°C for 5 hours, (b) is an SEM photograph showing sample 2 after annealing at 780°C for 8 hours, (c) is an optical microscope photograph showing sample 3 after annealing at 820°C for 8 hours, and (d) is an optical microscope photograph showing sample 4 after annealing at 860°C for 8 hours. [Figure 4] (a) is an SEM photograph showing an enlarged view around the crystal phase, and (b) is a diagram showing the result of performing elemental mapping by energy dispersive X-ray spectroscopy (EDS) on (a). [Figure 5] (a) is a graph showing the Raman spectrum at the point analysis position A of the amorphous phase in FIG. 4, and (b) is a graph showing the Raman spectrum at the point analysis position B of the crystal phase in FIG. 4.

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the examples of the embodiments and examples shown below.

[0019] The inventors have found that the locally crystallized glass according to the present invention can be obtained by annealing a glass in which a metal dopant is locally present at a specific temperature.

[0020] (Locally Crystallized Glass) The locally crystallized glass of this embodiment is a glass having a localized crystalline phase containing a metal dopant (see Figures 3(c) and 3(d)). Since the crystalline phase and amorphous phase in the locally crystallized glass of this embodiment have different physical properties such as thermal and optical properties, the physical properties of the locally crystallized glass, such as thermal and optical properties, can be controlled by the distribution of the localized crystalline phase within the glass.

[0021] The "thermal properties" of glass refer to characteristics such as the characteristic temperature (transition point), thermal expansion coefficient, specific heat, and thermal conductivity. For example, the crystalline phase in this embodiment has a lower thermal expansion coefficient than the amorphous phase, resulting in improved thermal properties.

[0022] Furthermore, the "optical properties" of glass refer to characteristics such as transmission, absorption, scattering, reflection, and refraction of light incident on the glass. For example, the crystalline phase in this embodiment appears white due to the diffuse reflection of incident light.

[0023] In the locally crystallized glass of this embodiment, the base glass, that is, the glass constituting the amorphous phase in the locally crystallized glass, can be any type of glass, such as quartz glass, borosilicate glass, or soda-lime glass, as long as it can undergo the metal sphere introduction treatment and annealing treatment described later.

[0024] The base glass for locally crystallized glass is preferably soda-lime glass, which allows for high-precision control of the distribution of the crystalline phase within the glass. In this case, the crystalline phase has more calcium (Ca) and magnesium (Mg) and less sodium (Na) compared to the amorphous phase, and the inclusion of CaMgSi2O6 and / or CaSiO3 in the crystalline phase enhances heat resistance and mechanical strength.

[0025] Furthermore, commercially available glass can be used as the base glass for the locally crystallized glass. The thickness of the glass should be sufficient to allow the laser light irradiated during the metal sphere introduction process described later to pass through, melt due to heat, and form and move the metal sphere inside, and is preferably 100 μm to 10 cm.

[0026] In the locally crystallized glass of this embodiment, local crystallization can be promoted by using metal dopants contained in the crystalline phase, such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), zirconium (Zr), and manganese (Mn), or alloys containing at least one of these metals.

[0027] The metal dopant is preferably Mn, which allows for high-concentration doping of the glass with the metal dopant, thereby increasing the design flexibility of the crystalline phase. Depending on its application, the locally crystallized glass may contain metal dopants other than the one that promotes local crystallization described above in its crystalline or amorphous phase. For example, for use as a photoelectric fusion substrate, the optical properties of the locally crystallized glass can be improved by separately containing Li, Zr, and rare earth elements, or alloys containing at least one of these metals. Furthermore, for use as an all-solid-state battery material, the electrolytic performance of the locally crystallized glass can be improved by separately containing Na, Al, and Fe, or alloys containing at least one of these metals.

[0028] Here, the crystalline phase is the metal-doped portion of the metal-doped glass obtained by the metal-doping process of the locally crystallized glass manufacturing method described later, which has been crystallized by annealing. The "metal-doped portion" refers to the part of the metal sphere's movement trajectory that contains metal nanoparticles separated from the metal sphere.

[0029] Furthermore, the crystalline phase can be broadly classified into two types based on the shape of the crystals. Specifically, angular crystals are abundant in the center of the crystalline phase, i.e., in the cross-sectional view perpendicular to the direction of movement in the trajectory of the metal sphere, while needle-shaped crystals are abundant in the surrounding area (see Figure 3(d)). This distribution of needle-shaped crystals around the crystalline phase suppresses thermal expansion in the periphery of the crystalline phase, thereby improving its thermal properties. Here, crystals with an aspect ratio of less than 3 in the cross-sectional view are classified as angular, and those with an aspect ratio of 3 or more are classified as needle-shaped.

[0030] Furthermore, the crystallization range of the crystalline phase, that is, the range in which crystallization occurs within the glass, is a range slightly wider than the maximum cross-sectional area of ​​the metal sphere's movement trajectory (a range of circles with a diameter approximately 20% longer than the diameter of the metal sphere's movement trajectory) when viewed in a cross-sectional view perpendicular to the direction of movement of the metal sphere's movement trajectory. Preferably, it is a range of circles with a diameter of 0.1 μm to 500 μm, and more preferably a range of circles with a diameter of 10 μm to 200 μm. This allows for high-precision control of physical properties such as thermal and optical properties in locally crystallized glass. The diameter of the metal sphere's movement trajectory formed by the metal doping process is approximately 0.5 to several times the diameter of the metal sphere. More specifically, the diameter of the metal sphere's movement trajectory is preferably several tens of μm smaller to several hundred μm larger than the diameter of the metal sphere, and is formed within a range of size corresponding to the crystallization range of the crystalline phase described above.

[0031] (Method for manufacturing locally crystallized glass) The method for manufacturing locally crystallized glass according to this embodiment comprises a metal doping step in which a metal thin film, metal powder, or metal foil is arranged in glass, i.e., a base glass for locally crystallized glass, and laser light is irradiated from the glass side to form metal spheres inside the glass, and metal fine particles are separated from the metal spheres while moving the metal spheres; and an annealing step in which the metal doped glass obtained in the metal doping step is annealed.

[0032] In the metal doping process, a laser beam is focused and irradiated onto a thin metal film, metal powder, or metal foil from the glass side. This heats the metal in the irradiated area, causing it to melt, and the surrounding glass also melts (softens) due to the heat transfer. As a result, the molten metal moves in the direction from which the light was irradiated, i.e., towards the laser oscillator, and is introduced into the softened glass as a metal sphere.

[0033] Furthermore, in the metal doping process, the thickness of the metal thin film should be sufficient to form metal spheres inside the glass, preferably 0.1 μm or more and 1 mm or less, more preferably 0.1 μm or more and 100 μm or less, and even more preferably 1 μm or more and 10 μm or less.

[0034] Furthermore, if it is a metal powder, its average particle size is preferably 0.1 μm to 300 μm, and more preferably 1 μm to 100 μm. Also, the thickness of the layer formed by the metal powder is preferably 0.1 μm to 1 mm, more preferably 0.1 μm to 100 μm, and even more preferably 1 μm to 10 μm.

[0035] Furthermore, in the metal doping process, the wavelength of the laser light should be such that it is possible to introduce metal spheres into the glass that forms the base of the locally crystallized glass and to dope the movement trajectory of the metal spheres with metal nanoparticles. Preferably, it is 350 nm to 2000 nm, and more preferably 450 nm to 1100 nm.

[0036] Furthermore, the laser light intensity should be sufficient to introduce metal spheres into the glass that forms the base of the locally crystallized glass, and to dope the trajectory of the moving metal spheres with metal nanoparticles, preferably 10 kW / cm². 2 Above 200kW / cm² 2 The following is more preferable: 10 kW / cm² 2 Above 100kW / cm² 2 The following, and more preferably 10 kW / cm² 2More than 50kW / cm 2 That is the case.

[0037] Furthermore, it is preferable that the laser light is focused into a spot and irradiated, and the diameter of this spot is preferably 10 μm to 1000 μm, and more preferably 20 μm to 500 μm.

[0038] Furthermore, in the metal doping process, the laser light irradiation time can be appropriately adjusted according to the wavelength and intensity of the laser light as described above.

[0039] Furthermore, in the metal doping process, the size of the metal spheres introduced into the glass is 3 μm to 300 μm in diameter, preferably 10 μm to 300 μm, and more preferably 50 μm to 300 μm.

[0040] Furthermore, in the metal doping process, metal particles are separated from the metal spheres by moving the metal spheres inside the glass. The size of the metal particles separated from the metal spheres is preferably 0.01 μm to 10 μm in diameter, and more preferably 0.03 μm to 1 μm in diameter.

[0041] In the metal doping process, the metal spheres move in the direction from which the laser light is incident. Therefore, if the relative positions of the laser light and the glass are fixed, the trajectory of the metal spheres will be linear. However, by changing the angle of incidence of the laser light to the glass during laser irradiation, the trajectory of the metal spheres can be bent or curved. Thus, in the metal doping process, it is possible to manipulate the trajectory of the metal spheres inside the glass.

[0042] Furthermore, in the metal doping process, by placing borosilicate glass between the glass and the thin metal film, metal powder, or metal foil, it is possible to prevent the heated metal from directly adhering to and cracking the surface of heat-sensitive soda-lime glass, for example, and to facilitate the introduction of metal spheres into the glass. The thickness of the borosilicate glass in this case is preferably between 100 μm and 5 mm.

[0043] In the annealing process, the metal-doped glass obtained in the metal-doping process is annealed at a temperature above the glass transition temperature, preferably between 760°C and 900°C, thereby promoting the crystallization of the metal-doped portion.

[0044] Furthermore, in the annealing process, the metal-doped glass obtained in the metal-doping process is preferably annealed at 840°C or higher, more preferably at 860°C or higher, which allows for complete crystallization of the metal-doped portion, particularly the metal fine particles separated along the movement trajectory of the metal spheres.

[0045] Furthermore, in the annealing process, the processing time is preferably 6 hours or more, more preferably 16 hours or more, at the heating temperature described above. The inventors have confirmed that crystallization progresses as the processing time of the annealing process increases. [Examples]

[0046] Here, locally crystallized glass was produced using the method for producing locally crystallized glass described in the embodiment above. This will be explained in detail below.

[0047] First, a metal doping process is performed. Figure 1 shows an example of the configuration of a metal sphere introduction device for introducing metal spheres into the glass that will form the base of the locally crystallized glass.

[0048] In this embodiment, the metal sphere introduction device is fixed to a jig (not shown) with the following layers stacked in order from the laser oscillator side: soda-lime glass (AGC Corporation, architectural float glass), borosilicate glass (SCHOTT AG Corporation, TEMPAX Float), Mn powder (Nilaco Corporation, MN-287301), and thermal insulation material. In this embodiment, the soda-lime glass that forms the base of the locally crystallized glass is 10 mm thick. The borosilicate glass is 5 mm thick. The borosilicate glass used as thermal insulation material is also 5 mm thick. The Mn powder has an average particle size of 75 μm and is used in a 100 μm thick layer.

[0049] Furthermore, the laser oscillator used is a fiber laser (manufactured by Wuhan Raycus Fiber Laser Technologies, model RFE-C020 / A / 2 / A, product name "Raycus") capable of continuous oscillation at a beam diameter of 4 mm and a wavelength of 1064 nm. The laser light emitted from the fiber laser is focused using a lens with a focal length of 40 mm.

[0050] In this embodiment, the laser beam output is set to 7W and the spot diameter to 400μm, and the laser beam is irradiated onto Mn powder through soda-lime glass and borosilicate glass. This introduces Mn metal spheres with a diameter of 150-250μm into the borosilicate glass, and these metal spheres can be moved to just before the area to be doped inside the soda-lime glass. Furthermore, the laser beam output is set to 10W and the spot diameter to 150μm, and the laser beam is irradiated onto the Mn metal spheres through the soda-lime glass. This allows the metal spheres to be moved while simultaneously doping their trajectory with Mn.

[0051] As shown in Figures 2(a) and (b), the trajectory of the Mn metal sphere, i.e., the cross-section of the metal-doped portion of Mn, was observed using a scanning electron microscope (JEOL Ltd., JSM-6510A). The results showed that Mn metal nanoparticles were separated along the trajectory of the Mn metal sphere, confirming that the material was doped with Mn metal. In this example, the size of the Mn metal nanoparticles separated from the Mn metal sphere was confirmed to be approximately 0.3 to 0.6 μm in diameter.

[0052] Next, an annealing process is performed. Samples 1 to 4, which are Mn-doped soda-lime glass, i.e., metal-doped glass, are placed in an electric furnace and annealed. The cross-section of the movement trajectory before and after annealing, i.e., the change in the metal-doped portion, is observed using an optical microscope or a scanning electron microscope (JEOL Ltd., JSM-6510A). The annealing conditions for samples 1 to 4 are shown in Table 1.

[0053] [Table 1]

[0054] As shown in Figures 3(a) and 3(b), approximately the same number of Mn metal nanoparticles were observed in the metal-doped areas before and after annealing for both Sample 1, which was annealed at 750°C for 5 hours, and Sample 2, which was annealed at 780°C for 8 hours.

[0055] In contrast, as shown in Figure 3(c), for sample 3, which was annealed at 820°C for 8 hours, the number of Mn metal nanoparticles in the metal-doped portion before and after annealing decreased by approximately 25%, and a white area was observed inside the glass.

[0056] Furthermore, as shown in Figure 3(d), in sample 4, which was annealed at 860°C for 8 hours, all Mn metal nanoparticles were removed from the metal-doped portion after annealing, and a white area was observed inside the glass.

[0057] Here, as a result of performing component analysis on the white-appearing portions of Samples 3 and 4 after annealing treatment by energy dispersive X-ray spectroscopy (EDS), it was confirmed that there was no difference in the ratio of the components of Si and O between the glass portion (amorphous phase) and the white-appearing portion.

[0058] Also, as shown in Fig. 4(b), as a result of performing elemental mapping on Na, Mg, and Ca contained in the soda-lime glass, it was confirmed that in the white-appearing portion, Mg and Ca increased and Na decreased compared to the glass portion (amorphous phase).

[0059] Furthermore, regarding the point analysis position A of the glass portion (amorphous phase) and the point analysis position B of the white-appearing portion in Fig. 4(a), as a result of obtaining Raman spectra, at the point analysis position A, broad peaks with a half-width of about 110 cm were obtained near 580 cm -1 and 1100 cm -1 (see Fig. 5(a)). On the other hand, at the point analysis position B, sharp peaks with a half-width of about 10 cm were obtained near 320 cm -1 (see Fig. 5(b)). This indicates that the white-appearing portion has high crystallinity, and it was confirmed that the white-appearing portion has become a crystalline phase in which the soda-lime glass has undergone alteration and crystallization. -1 、390 cm -1 、670 cm -1 and 1010 cm -1 (see Fig. 5(b)). This indicates that the white-appearing portion has high crystallinity, and it was confirmed that the white-appearing portion has become a crystalline phase in which the soda-lime glass has undergone alteration and crystallization. -1 (see Fig. 5(b)). This indicates that the white-appearing portion has high crystallinity, and it was confirmed that the white-appearing portion has become a crystalline phase in which the soda-lime glass has undergone alteration and crystallization.

[0060] Also, as described above, since it was confirmed that Mg and Ca were more abundant than Na in the crystalline phase, it was confirmed by EPMA (electron probe microanalyzer) that Mg and Ca were preferentially incorporated into the crystal lattice, and the crystalline phase contains CaMgSi2O6 or CaSiO3. Table 2 shows the elemental composition data of the crystalline phase obtained by performing simple quantitative analysis by the ZAF method, and Table 3 shows the elemental composition data of the amorphous phase.

[0061] [Table 2]

[0062] [Table 3]

[0063] Furthermore, the inventors have confirmed that Mn metal nanoparticles are dissolved as Mn ions in both the crystalline and amorphous phases. It has also been confirmed that Mn ions are present in greater quantities in the amorphous phase than in the crystalline phase.

[0064] Furthermore, analysis of the crystalline phase by electron diffraction revealed that, as shown in Figure 3(d), angular crystals are predominantly distributed in the center of the crystalline phase, while needle-shaped crystals are predominantly distributed in the surrounding area.

[0065] Furthermore, the crystallization range of the crystalline phase shown in Figure 3(d) was approximately 150 μm in diameter.

[0066] Thus, in this embodiment, it was confirmed that annealing at 800°C or higher, preferably 820°C or higher, can promote the crystallization of the metal-doped portion, i.e., the movement trajectory of the Mn metal spheres, and that annealing at 840°C or higher, preferably 860°C or higher, can completely crystallize the metal-doped portion.

[0067] As described above, the locally crystallized glass of the present invention is a glass having a localized crystalline phase containing metal dopant, which is obtained by annealing a metal-doped glass in which metal dopant is locally doped, thereby crystallizing only the metal-doped portion. As a result, a glass is obtained in which physical properties such as thermal properties and optical properties can be controlled by the distribution of the localized crystalline phase.

[0068] Furthermore, in the locally crystallized glass of the present invention, the distribution of the crystalline phase formed after annealing can be arbitrarily controlled by manipulating the movement trajectory of metal spheres in the metal doping step of the manufacturing method of locally crystallized glass. Additionally, by adjusting the size of the metal spheres in the metal doping step and the size of the metal nanoparticles (metal dopants) separated from the metal spheres by their movement trajectory, the crystallization range of the crystalline portion formed after annealing can be arbitrarily controlled within a diameter range of 0.1 μm to 500 μm. As a result, for example, it is possible to construct a three-dimensional optical waveguide by patterning the crystalline phase inside the locally crystallized glass. It is also possible to selectively introduce a zero thermal expansion region inside the glass by controlling the composition ratio of the crystalline phase.

[0069] Although embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included.

[0070] For example, in the above embodiment, an example was described in which locally crystallized glass is manufactured from metal-doped glass in which Mn is doped as a metal dopant into a base soda-lime glass. However, it goes without saying that even if the combination of the base glass and the metal dopant of the locally crystallized glass is different, locally crystallized glass having a local crystalline phase containing a metal dopant can be obtained.

[0071] Furthermore, while the above embodiment showed that the crystalline phase changes due to the annealing treatment of the movement trajectory of the metal spheres, which are the metal-doped portion, it goes without saying that crystallization is also promoted in the residual portion of the metal spheres, which are also the metal-doped portion, and a crystalline phase is formed.

[0072] Furthermore, while the above-described embodiment described an approach in which Mn metal spheres are introduced and moved by irradiating Mn powder with laser light, it goes without saying that the introduction and movement of Mn metal spheres may also be performed by irradiating a Mn thin film or Mn foil with laser light under appropriate conditions. [Industrial applicability]

[0073] This invention utilizes a completely novel method involving the introduction of metal spheres into the glass, making it possible to arbitrarily control the localized distribution of crystalline phases containing metal dopants. This allows for the creation of locally crystallized glass in which physical properties such as thermal and optical properties can be controlled by the localized distribution of crystalline phases within the glass. As a result, it has industrial potential as it can impart new functionality to crystallized glass. Furthermore, the locally crystallized glass of this invention can be used not only as an optical device, photoelectric integration substrate, or all-solid-state battery material with newly imbued physical properties such as thermal and optical properties by controlling the composition and distribution of the crystalline phases, but also as an object in which letters, symbols, or figures can be inscribed by the distribution of the crystalline phases and embedded within the glass, thus offering a wide range of applications.

Claims

1. A locally crystallized glass characterized by having a localized crystalline phase containing a metal dopant.

2. The locally crystallized glass according to claim 1, characterized in that the glass is soda-lime glass.

3. The locally crystallized glass according to claim 1, characterized in that needle-shaped crystals are more abundantly distributed in the periphery than in the center of the crystalline phase.

4. The crystalline phase is CaMgSi ２ O ６ and Casio ３ The locally crystallized glass according to claim 1, characterized by comprising at least one of the following.

5. The locally crystallized glass according to claim 1, characterized in that the crystalline phase has more Ca and Mg and less Na compared to the amorphous phase.

6. The locally crystallized glass according to claim 1, characterized in that the crystalline phase has a crystallization range with a diameter of 0.1 μm or more and 500 μm or less.

7. The locally crystallized glass according to any one of claims 1 to 6, characterized in that the metal dopant is Mn.

8. A metal doping process is performed in which a metal thin film, metal powder, or metal foil is arranged in a glass, and a laser beam is irradiated from the glass side onto the metal thin film, metal powder, or metal foil to form metal spheres inside the glass, and while moving the metal spheres, metal fine particles are separated from the metal spheres. An annealing step is performed to anneal the metal-doped glass obtained by the metal-doping step, A method for producing locally crystallized glass, characterized by comprising the following features.

9. The method for producing locally crystallized glass according to claim 8, characterized in that the annealing treatment is performed above the glass transition temperature.

10. The method for producing locally crystallized glass according to claim 8 or 9, characterized in that the metal is Mn.

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