Manufacturing methods for crystal glass, high-frequency substrates, liquid crystal antennas, and crystal glass.

Abstract

The present invention relates to a crystalline glass containing crystals of at least one of hexagonal cordierite and cordierite, wherein the total amount of said crystals is 40% or more by mass of said crystalline glass, and said crystals contain at least one of vacancies and other elements at Al sites.

Description

Technical Field

[0001] This invention relates to crystal glass, high-frequency substrates, liquid crystal antennas, and methods for manufacturing crystal glass. Background Technology

[0002] In recent years, wireless transmission using microwave and millimeter-wave bands has attracted much attention as a high-capacity transmission technology. As the frequency used increases, the signal frequency becomes higher, which in turn requires dielectric substrates with excellent dielectric properties at high frequencies.

[0003] Materials used as dielectric substrates include, for example, quartz, ceramics, and glass. Among glasses, crystalline glass, formed by crystallizing a portion of the glass, has the advantages of being easier to mold and cheaper to manufacture than quartz or ceramics, and can produce superior dielectric properties. Examples of crystalline glasses with excellent dielectric properties include, for instance, the crystalline glass containing hexagonal cordierite or cordierite crystals disclosed in Patent Document 1.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2020 / 023205 Summary of the Invention

[0007] However, the following problem exists: if the proportion of hexagonal cordierite or cordierite crystals in the crystalline glass is increased in order to improve dielectric properties, cracks will occur due to the difference in thermal expansion coefficients between the crystalline phase and the glass phase.

[0008] Therefore, the purpose of this invention is to solve the above-mentioned problems and provide a crystalline glass that contains a large amount of hexagonal cordierite or cordierite crystals to achieve excellent dielectric properties and suppress cracking.

[0009] That is, the present invention provides a crystalline glass containing crystals of at least one of hexagonal cordierite and cordierite.

[0010] The total amount of the above-mentioned crystals is 40% or more of the mass of the above-mentioned crystallized glass.

[0011] The crystals described above contain at least one of vacancies and foreign elements at the Al sites.

[0012] In one embodiment of the crystal glass of the present invention, the total of the portion containing at least one of the above-mentioned vacancies and the above-mentioned foreign elements is 4 at least 4 atom% of the above-mentioned Al sites.

[0013] In one embodiment of the crystal glass of the present invention, expressed as an oxide-based mass percentage, it may contain 45-60% SiO2, 20-35% Al2O3, and 9-15% MgO.

[0014] In one embodiment of the crystal glass of the present invention, the crystal glass may contain 5 to 15% TiO2, expressed as a mass percentage based on oxides.

[0015] In one embodiment of the crystal glass of the present invention, the glass may contain 0.5 to 15% P2O5, expressed as a mass percentage based on oxides.

[0016] In one embodiment of the crystal glass of the present invention, the crystal glass may have opposing main surfaces, the area of ​​which may be 100 to 100,000 cm². 2 The thickness can be 0.01 to 2 mm.

[0017] In one embodiment of the crystal glass of the present invention, the thermal conductivity at 20°C can be 1.0 W / (m·K) or higher.

[0018] In one embodiment of the crystal glass of the present invention, the relative permittivity at 20°C and 10 GHz can be 7 or less.

[0019] In one embodiment of the crystal glass of the present invention, the dielectric loss tangent at 20°C and 10GHz can be less than 0.003.

[0020] In one embodiment of the crystal glass of the present invention, the average coefficient of thermal expansion at 50–350°C can be 1 ppm / °C or higher.

[0021] The present invention provides a high-frequency substrate using the above-described crystal glass.

[0022] The present invention provides an antenna for liquid crystal using the above-described crystal glass.

[0023] The present invention provides an amorphous glass, which, expressed as an oxide-based mass percentage, contains 45-60% SiO2, 20-35% Al2O3, 9-15% MgO, 0.5-15% P2O5, and 5-15% TiO2.

[0024] This invention provides a method for manufacturing crystal glass, comprising:

[0025] Prepare an amorphous glass containing, by mass percentage (based on oxides): 45–60% SiO2, 20–35% Al2O3, and 9–15% MgO.

[0026] The amorphous glass described above is subjected to heat treatment;

[0027] The heat treatment described above includes: precipitating at least one of hexagonal cordierite and cordierite crystals, such that the Al sites of the crystals contain at least one of vacancies and other elements.

[0028] In one embodiment of the method for manufacturing the crystal glass of the present invention, the amorphous glass, expressed as an oxide-based mass percentage, may contain 0.5 to 15% P2O5 and 5 to 15% TiO2.

[0029] In one embodiment of the method for manufacturing the crystalline glass of the present invention, the amorphous glass may have opposing main surfaces, the area of ​​which may be 100 to 100,000 cm². 2 The thickness of the aforementioned amorphous glass can be 0.01 to 2 mm.

[0030] In one embodiment of the method for manufacturing the crystal glass of the present invention, the heat treatment may include holding the amorphous glass at a temperature of 960°C or higher for 0.5 hours or more.

[0031] In one embodiment of the method for manufacturing the crystallized glass of the present invention, the heat treatment may include holding in a first temperature region and holding in a second temperature region, wherein the first temperature region may be 760°C to 960°C, and the holding time in the first temperature region may be 0.5 hours or more.

[0032] The second temperature range can be 960℃ to 1350℃, and the holding time in the second temperature range can be more than 0.5 hours.

[0033] According to the present invention, a crystalline glass and a high-frequency substrate and a liquid crystal antenna using the crystalline glass are obtained. The crystalline glass achieves excellent dielectric properties by containing at least 40% by mass of hexagonal cordierite and cordierite, and by including at least one of vacancies and foreign elements at Al sites in the crystal, cracks caused by the difference in thermal expansion coefficients between the crystalline phase and the glass phase can be suppressed. Attached Figure Description

[0034] Figure 1 It is a diagram that schematically illustrates the temperature changes during two stages of heat treatment. Detailed Implementation

[0035] In this specification, the "~" sign indicating a numerical range is used to encompass the values ​​preceding and following it as the lower and upper limits. Unless otherwise specified, the "~" sign will have the same meaning throughout this specification.

[0036] In this specification, unless otherwise specified, the glass composition is expressed as a percentage by mass based on oxides, abbreviated as "%". It should be noted that in this specification, the proportions (percentages, etc.) based on mass and weight are the same.

[0037] Furthermore, "substantially does not contain" in this specification means below the level of impurities present in raw materials, etc., i.e., not intentionally contained. Specifically, for example, less than 0.1% by mass.

[0038] In this specification, "crystalline glass" refers to glass in which crystals have precipitated. In this application, "crystalline glass" refers to glass in which diffraction peaks indicating crystals are confirmed by X-ray diffraction (XRD). X-ray diffraction measurements can be performed, for example, using CuKα rays in the range of 2θ from 10° to 80°. If diffraction peaks are observed, the precipitated crystals can be identified, for example, by using the three-strong-line method.

[0039] <Crystal Glass>

[0040] The crystalline glass involved in this embodiment (hereinafter also referred to as the crystalline glass) is a crystalline glass containing crystals of at least one of hexagonal cordierite and cordierite, wherein the total amount of the crystals is 40% or more by mass of the crystalline glass, and the crystals contain at least one of vacancies and foreign elements at the Al sites.

[0041] (Crystal)

[0042] This crystalline glass contains crystals of at least one of hexagonal cordierite and cordierite. Hexagonal cordierite and cordierite are MgO-Al2O3-SiO2 system crystals with the same composition but different crystal structures. The composition of these crystals is based on the chemical formula Mg2Al4Si5O. 18 This indicates that cordierite, synthesized via a solid-state reaction, is a low-temperature type with an orthorhombic crystal structure, while hexagonal cordierite is a high-temperature type with a hexagonal crystal structure. Hereinafter, in this specification, the crystals of at least one of hexagonal cordierite and cordierite contained in the crystallizing glass will sometimes be collectively referred to as "hexagonal cordierite / cordierite crystals." That is, "hexagonal cordierite / cordierite crystals" refers to the crystal of only one of hexagonal cordierite and cordierite when the crystallizing glass contains both, and refers to the crystals of both.

[0043] For insulating substrates used in high-frequency equipment, in order to ensure the quality or strength of high-frequency signals, it is required to reduce transmission losses based on dielectric loss or conductor loss. Crystalline glasses containing hexagonal cordierite / cordierite crystals tend to have a lower dielectric loss tangent or relative permittivity as the proportion of this crystal in the crystalline glass increases. Furthermore, among hexagonal cordierite and cordierite, hexagonal cordierite tends to have superior dielectric properties, and crystalline glasses containing hexagonal cordierite are preferred.

[0044] From the viewpoint of obtaining a crystalline glass with excellent dielectric properties, the total amount of hexagonal cordierite / cordierite crystals in this crystalline glass is 40% or more by mass of the crystalline glass. Furthermore, the total amount of hexagonal cordierite / cordierite crystals is preferably 50% or more by mass, more preferably 55% or more by mass, and even more preferably 60% or more by mass.

[0045] Furthermore, from the viewpoint of suppressing cracks caused by the difference in thermal expansion rates between the crystalline phase and the glass phase, or from the viewpoint of ensuring a sufficient thermal expansion rate for a crystalline glass, the total amount of hexagonal cordierite / cordierite crystals is preferably 90% or less of the crystalline glass, more preferably 85% or less, and even more preferably 80% or less.

[0046] Here, hexagonal cordierite / cordierite crystals can be identified by X-ray diffraction (XRD). Specifically, the bulk of the crystalline glass can be crushed, and when measured by CuKα rays at 2θ = 10 to 90°, if the peak with the highest intensity is identified in the range of 2θ = 10 to 11°, which can be defined as the peak of the (100) plane, the crystalline glass contains crystals of at least one of hexagonal cordierite and cordierite.

[0047] Furthermore, to obtain a more accurate crystal structure, Rietveld analysis is preferred. Rietveld analysis allows for quantitative analysis of crystalline and amorphous phases, as well as structural analysis of crystalline phases. The Rietveld method is described in the "Crystallization Analysis Handbook" (Kyoritsu Publishing, 1999, pp. 492-499), edited by the Editorial Committee of the "Crystallization Analysis Handbook" of the Japanese Crystallography Society. The content of hexagonal cordierite / cordierite crystals in this crystalline glass can be calculated using Rietveld analysis based on XRD measurements.

[0048] In this crystalline glass, the hexagonal cordierite / cordierite crystals contain at least one of vacancies and foreign elements at the Al sites. Here, a foreign element refers to an element other than Al. That is, in the hexagonal cordierite / cordierite crystals of this crystalline glass, sites that should ideally be occupied by Al atoms when replicating the ideal crystal structure include portions where Al atoms are absent. When the portion lacking Al atoms also lacks any atoms, including those containing foreign elements, this portion is a vacancy; when it contains atoms of foreign elements, this portion is a portion containing foreign elements.

[0049] As a dissimilar element, there are no particular limitations; for example, elements other than Al whose atomic size is close to that of Al atoms can be cited. Specifically, Mg and Si can be cited as examples of such elements.

[0050] Hexagonal cordierite / cordierite crystals, by incorporating at least one of vacancies and foreign elements at Al sites, can suppress cracking in crystalline glasses caused by the difference in thermal expansion rates between the crystalline and glassy phases. The inclusion of vacancies and foreign elements at Al sites in hexagonal cordierite / cordierite crystals results in a structure with a degree of deformation compared to an ideal crystal structure; that is, the lattice constant is elongated or contracted only along a certain axis compared to the original lattice constant. Therefore, it is believed that this can alleviate the stress generated in crystalline glasses due to the difference in thermal expansion rates between the crystalline and glassy phases, thus suppressing cracking.

[0051] Furthermore, when hexagonal cordierite / cordierite crystals contain vacancies at Al sites, the number of atoms in the crystal decreases compared to the case with an ideal crystal structure. It is known that dielectric properties vary with the number of electrons, with a tendency for a higher dielectric constant as the number of electrons increases. That is, by introducing vacancies at Al sites, the number of electrons decreases compared to the case with Al atoms, thus it is believed that the dielectric properties of crystalline glasses can be improved.

[0052] Furthermore, it is believed that when Al sites contain a different element, the number of electrons is reduced compared to when Al atoms are present, which also makes it easier to improve dielectric properties. Therefore, from the viewpoint of further improving dielectric properties, it is preferable that the number of electrons in the different element is less than that in Al. Mg can be cited as an example of such a different element.

[0053] In hexagonal cordierite / cordierite crystals, from the viewpoint of improving crack suppression, the total percentage of Al sites containing at least one of vacancies and foreign elements, i.e., the portion where Al atoms are absent at Al sites, is preferably 4 atom% or more of the Al sites. More preferably, the total percentage of the portion where Al atoms are absent is 5 atom% or more, further preferably 7.5 atom% or more, even more preferably 9 atom% or more, particularly preferably 10 atom% or more, and even more particularly preferably 12 atom% or more.

[0054] Furthermore, from the viewpoint of maintaining the crystal structure, the total amount of the portion at which Al atoms are not present at Al sites is preferably 50 atom% or less, more preferably 35 atom% or less, and even more preferably 20 atom% or less.

[0055] The portion without Al atoms can be entirely vacant or entirely contain foreign elements. From the viewpoint of further enhancing the effect of crack suppression or improving dielectric properties, it is preferable to contain vacant sites, and more preferably, the portion with more vacant sites than the portion containing foreign elements.

[0056] The total percentage of the portion lacking Al atoms relative to the number of Al sites is the atomic fraction (atom%) of the portion lacking Al atoms relative to the sites that Al atoms would normally occupy in a replicated ideal crystal structure. This percentage can be calculated using Rietwald analysis based on XRD measurements.

[0057] To the extent that it does not impair the effects of the present invention, the crystalline glass may contain crystals other than hexagonal cordierite / cordierite crystals. Examples of crystals other than hexagonal cordierite / cordierite crystals include mullite, corundum, rutile, and anatase. When containing crystals other than hexagonal cordierite / cordierite crystals, the total content of such crystals relative to the total content of the crystalline glass is preferably 15% by mass or less, more preferably 12.5% ​​by mass or less, and even more preferably 10% by mass or less. The identification of the crystal types and the determination of the content of crystals other than hexagonal cordierite / cordierite crystals can be performed by the above-described XRD determination and Rietwald analysis using the XRD determination results.

[0058] (composition)

[0059] The composition of this crystalline glass is the same as that of the amorphous glass before crystallization in the manufacturing method described later. Therefore, the preferred composition of this crystalline glass is the same as that of the amorphous glass. Here, the composition of the crystalline glass in this specification refers to the combined composition of the crystalline phase and the glass phase. Furthermore, the composition of the crystalline glass can be determined by analyzing the substance obtained by vitrifying the crystalline glass by heat treatment at a temperature above its melting point. X-ray fluorescence analysis can be used as an analytical method. Additionally, the composition of the crystalline phase of this crystalline glass can be analyzed by Ritvold analysis of the results of the above-described XRD measurements. The preferred lower limit for the content of non-essential components in the composition of this crystalline glass is 0%.

[0060] The composition of this crystalline glass is not particularly limited, but is expressed as a mass percentage based on oxides. It preferably contains 45-60% SiO2, 20-35% Al2O3, and 9-15% MgO. SiO2, Al2O3, and MgO are the components that constitute hexagonal cordierite / cordierite crystals.

[0061] SiO2 is used to precipitate hexagonal cordierite / cordierite crystals, which are the crystalline phase. The SiO2 content is preferably 45% or more. By ensuring the SiO2 content is 45% or more, the precipitated crystalline phase of the crystal glass is easily stabilized. The SiO2 content is more preferably 45.2% or more, further preferably 45.5% or more, even more preferably 45.7% or more, particularly preferably 46% or more, further preferably 46.2% or more, and most preferably 46.5% or more. Furthermore, the SiO2 content is preferably 60% or less. If the SiO2 content is 60% or less, the melting and forming of the glass raw material is easier. Additionally, the heat treatment conditions are also an important factor in precipitating hexagonal cordierite / cordierite crystals, but by keeping the SiO2 content below the aforementioned upper limit, a wider range of heat treatment conditions can be selected. The SiO2 content is more preferably 58% or less, further preferably 56% or less, even more preferably 54% or less, particularly preferably 52% or less, further preferably 50% or less, and most preferably 48% or less.

[0062] Al2O3 is used to precipitate hexagonal cordierite / cordierite crystals as the crystalline phase. The content of Al2O3 is preferably 20% or more. If the Al2O3 content is 20% or more, the desired crystalline phase is easily obtained, the precipitated crystalline phase of the crystal glass is easily stabilized, and the rise in liquidus temperature can be suppressed. The Al2O3 content is more preferably 22% or more, further preferably 24% or more, even more preferably 26% or more, particularly preferably 28% or more, further preferably 29% or more, and most preferably 30% or more. On the other hand, the Al2O3 content is preferably 35% or less. If the Al2O3 content is 35% or less, the meltability of the glass raw material is easily improved. The Al2O3 content is more preferably 34.5% or less, further preferably 34% or less, even more preferably 33.5% or less, particularly preferably 33% or less, further preferably 32.5% or less, and most preferably 32% or less.

[0063] MgO is used to precipitate hexagonal cordierite / cordierite crystals, which are the crystalline phase. The MgO content is preferably 9% or more. If the MgO content is 9% or more, the desired crystals are easily obtained, the precipitated crystalline phase of the crystallizing glass is easily stabilized, and the meltability of the glass raw material is improved. The MgO content is more preferably 9.3% or more, further preferably 9.5% or more, even more preferably 9.7% or more, particularly preferably 10% or more, further preferably 10.2%, and most preferably 10.5% or more. On the other hand, the MgO content is preferably 15% or less. If the MgO content is 15% or less, the desired crystals are easily obtained. The MgO content is more preferably 14.5% or less, further preferably 14% or less, even more preferably 13.5% or less, particularly preferably 13% or less, further preferably 12.5% ​​or less, and most preferably 12% or less.

[0064] The crystallizing glass preferably contains components that form nuclei. These nuclei are components that can generate nuclei, serving as the starting point for crystal growth, during the crystallization of the amorphous glass. By containing components that form nuclei, the desired crystal structure or a state in which crystals are relatively uniformly dispersed within the crystallizing glass can be easily and stably obtained. Examples of nuclei include TiO2, MoO3, and ZrO2. From the viewpoint of stably precipitating hexagonal cordierite / cordierite crystals, TiO2 is preferred as a nuclei component.

[0065] From the viewpoint that the nucleating agent exists in the glass bulk at a certain concentration or higher, the total content of the nucleating agent is preferably 5% or more, more preferably 5.5% or more, further preferably 6.0% or more, even more preferably 6.5% or more, particularly preferably 7.0% or more, even more preferably 7.5%, and most preferably 8.0% or more. Furthermore, from the viewpoint of increasing the proportion of hexagonal cordierite / cordierite crystals in the crystalline glass bulk to improve dielectric properties, the total content of the nucleating agent is preferably 15% or less, more preferably 14.5% or less, even more preferably 14% or less, even more preferably 13.5% or less, particularly preferably 13% or less, even more preferably 12.5% ​​or less, and most preferably 12% or less.

[0066] TiO2 is not an essential component, but it functions not only as a nucleation component as described above, but also contributes to the refinement of the precipitated crystal phase, the improvement of the material's mechanical strength, and its chemical durability. From the viewpoint of stably precipitating hexagonal cordierite / cordierite crystals, the TiO2 content is preferably 5% or more, more preferably 5.5% or more, further preferably 6.0% or more, even more preferably 6.5% or more, particularly preferably 7.0% or more, further preferably 7.5%, and most preferably 8.0% or more. Furthermore, from the viewpoint of increasing the proportion of hexagonal cordierite / cordierite crystals in the overall crystalline glass to achieve good dielectric properties, the TiO2 content is preferably 15% or less, more preferably 14.5% or less, further preferably 14% or less, even more preferably 13.5% or less, particularly preferably 13% or less, further preferably 12.5% ​​or less, and most preferably 12% or less.

[0067] MoO3 is not an essential component, but rather functions as a nucleation component in the aforementioned formation process. From the viewpoint of stably precipitating hexagonal cordierite / cordierite crystals, the MoO3 content is preferably 5% or more, more preferably 5.5% or more, further preferably 6.0% or more, even more preferably 6.5% or more, particularly preferably 7.0% or more, even more preferably 7.5%, and most preferably 8.0% or more. Furthermore, from the viewpoint of increasing the proportion of hexagonal cordierite / cordierite crystals in the overall crystalline glass to achieve good dielectric properties, the MoO3 content is preferably 15% or less, more preferably 14.5% or less, even more preferably 14% or less, even more preferably 13.5% or less, particularly preferably 13% or less, even more preferably 12.5% ​​or less, and most preferably 12% or less.

[0068] ZrO2 is not an essential component, but it functions not only as a nucleation component as described above, but also contributes to the refinement of the precipitated crystal phase, the improvement of the material's mechanical strength, and its chemical durability. From the viewpoint of stably precipitating hexagonal cordierite / cordierite crystals, the ZrO2 content is preferably 5% or more, more preferably 5.5% or more, further preferably 6.0% or more, even more preferably 6.5% or more, particularly preferably 7.0% or more, further preferably 7.5%, and most preferably 8.0% or more. Furthermore, from the viewpoint of increasing the proportion of hexagonal cordierite / cordierite crystals in the overall crystalline glass to achieve good dielectric properties, the ZrO2 content is preferably 15% or less, more preferably 14.5% or less, further preferably 14% or less, even more preferably 13.5% or less, particularly preferably 13% or less, further preferably 12.5% ​​or less, and most preferably 12% or less.

[0069] This crystalline glass preferably contains components that generate vacancies. A component that generates vacancies refers to a component that readily forms at least one of the aforementioned portions lacking Al atoms, i.e., portions containing vacancies and foreign elements, at the Al sites of hexagonal cordierite / cordierite crystals. Examples of components that generate vacancies include P2O5 and B2O3. P2O5 is particularly preferred because it readily forms a large number of portions containing vacancies and foreign elements at the Al sites of hexagonal cordierite / cordierite crystals.

[0070] The reason why vacancy-generating components can easily form portions containing vacancies or foreign elements at Al sites is as follows: Vacancy-generating components, such as P₂O₅, cause minute phase separation during the crystallization process of heated amorphous glass. During the growth of hexagonal cordierite / cordierite crystals, crystals grow from the interfaces of these minute phase separations, thus increasing the dispersion of crystals in the crystalline glass and facilitating uniform crystal formation. Consequently, atoms surrounding the Al sites tend to compete for Al atoms during crystal growth. Therefore, Al sites easily become vacancies or readily acquire foreign elements such as Mg. It should be noted that when vacancy-generating components are added to form portions at Al sites lacking Al atoms, these portions are considered to easily contain vacancies, and compared to portions containing foreign elements, the number of vacancies tends to increase.

[0071] From the viewpoint that it is easy to form a portion without Al atoms at Al sites, the content of the component that generates vacancies is preferably 0.5% or more, more preferably 1% or more, further preferably 2% or more, and even more preferably 3% or more. On the other hand, from the viewpoint of suppressing the separation of the crystalline phase and the glassy phase and from the viewpoint of precipitating crystals stably, the content of the component that generates vacancies is preferably 15% or less, more preferably 7.5% or less, and even more preferably 3.5% or less.

[0072] P2O5 is not an essential component, but it is preferred to contain it because it functions as a vacancy-generating agent as described above. P2O5 not only functions as a vacancy-generating agent but also helps improve the meltability, formability, and devitrification resistance of the glass raw material. From the viewpoint of easily forming portions without Al atoms at Al sites, the content of P2O5 is preferably 0.5% or more, more preferably 0.75% or more, further preferably 1% or more, even more preferably 1.25% or more, particularly preferably 1.5% or more, further preferably 1.75%, and most preferably 2% or more. Furthermore, from the viewpoint of suppressing the separation of the crystalline phase and the glass phase and ensuring stable crystal precipitation, the content of P2O5 is preferably 15% or less, more preferably 13% or less, further preferably 11% or less, even more preferably 9% or less, particularly preferably 7% or less, further preferably 5% or less, and most preferably 3.5% or less.

[0073] B2O3 is not an essential component, but it can be included because it functions as a vacancy generator as described above. Furthermore, B2O3 also contributes to viscosity adjustment and crystallization temperature control during the melting and forming of glass raw materials. From the viewpoint of easily forming portions without Al atoms at Al sites, the content of B2O3 is preferably 0.5% or more, more preferably 0.75% or more, further preferably 1% or more, even more preferably 1.25% or more, particularly preferably 1.5% or more, further preferably 1.75%, and most preferably 2% or more. On the other hand, from the viewpoint of suppressing excessive viscosity decrease during crystallization and stably manufacturing glass, the content of B2O3 is preferably 10% or less, more preferably 9% or less, further preferably 8% or less, even more preferably 7% or less, particularly preferably 6% or less, further preferably 5% or less, and most preferably 4% or less.

[0074] Furthermore, when adding P2O5 and B2O3, from the viewpoint that it is easy to form a part without Al atoms at the Al site, the total amount is preferably 1% or more, and from the viewpoint of suppressing the separation of the crystalline phase and the glass phase and precipitating the crystal stably, the total amount is preferably 15% or less.

[0075] CaO may be absent, but since it improves the meltability of glass raw materials while preventing the coarsening of precipitated crystalline phases, it may be present in amounts of 4% or less. A more preferred range for the CaO content is 1% or more. Furthermore, a more preferred range for the CaO content is 3% or less.

[0076] BaO may be absent, but it may be present at 5% or less to improve the meltability of the glass raw material. A more preferred range for the BaO content is 1% or more. Furthermore, a more preferred range for the BaO content is 3% or less.

[0077] Sb2O3 and As2O3 may be absent, but in order to function as a clarifying agent during the melting of glass raw materials, they may be present in amounts of less than 1%.

[0078] F may be absent, but in order to improve the meltability of glass raw materials, it may contain less than 3% F.

[0079] SnO2, CeO, and Fe2O3 may be omitted, but in order to improve the detection sensitivity of glass colorants or surface defects caused by coloring and to improve the absorption characteristics of LD-excited solid-state lasers, the total content of each component may be less than 5%.

[0080] (physical properties)

[0081] From the viewpoint of improving dielectric properties, the dielectric loss tangent of this crystalline glass at 20°C and 10GHz is preferably 0.003 or less, more preferably 0.002 or less, even more preferably 0.0018 or less, even more preferably 0.0016 or less, particularly preferably 0.0014 or less, even more preferably 0.0012 or less, particularly preferably 0.001 or less, and most preferably 0.0008 or less. A smaller dielectric loss tangent at 20°C and 10GHz is better, but it is typically 0.0001 or more.

[0082] From the viewpoint of improving dielectric properties, the relative permittivity of this crystalline glass at 20°C and 10GHz is preferably 7 or less, more preferably 6.5 or less, and even more preferably 6 or less. The lower the relative permittivity at 20°C and 10GHz, the better, but it is generally 4.0 or more.

[0083] This crystalline glass exhibits excellent dielectric properties due to its high content of hexagonal cordierite / cordierite crystals. In this crystalline glass, if the dielectric loss tangent or relative permittivity at 20°C and 10GHz is within the preferred range described above, it is considered to also possess excellent dielectric properties for frequency bands higher than 10GHz. It should be noted that dielectric properties such as the dielectric loss tangent or relative permittivity can be determined using the split-pillar dielectric resonance method (SPDR).

[0084] From the viewpoint of efficiently dissipating heat generated when used as a substrate for high-frequency applications, the thermal conductivity of this crystalline glass at 20°C is preferably 1.0 W / (m·K) or higher, more preferably 1.5 W / (m·K) or higher, even more preferably 2.0 W / (m·K) or higher, even more preferably 2.5 W / (m·K) or higher, and particularly preferably 3.0 W / (m·K) or higher. The thermal conductivity can be measured using a laser flash thermophysical property measuring device based on the method specified in JIS R1611 (2010). Higher thermal conductivity is better, but it is typically 8.0 W / (m·K) or lower. The thermal conductivity can be adjusted by considering factors such as crystal content, crystal type, and crystal precipitation morphology. Thermal conductivity is particularly closely related to crystallinity; it is known that the thermal conductivity of uncrystallized glass is generally 1.0 W / (m·K) or lower, but the thermal conductivity of crystallized samples increases.

[0085] From the viewpoint of reducing the difference in thermal expansion coefficients when this crystalline glass is bonded to other components, the average coefficient of thermal expansion of this crystalline glass from 50 to 350°C is preferably 1 ppm / °C or higher, more preferably 1.5 ppm / °C or higher, even more preferably 1.75 ppm / °C or higher, particularly preferably 2.0 ppm / °C or higher, even more preferably 2.25 ppm / °C or higher, and most preferably 2.5 ppm / °C or higher. Similarly, from the viewpoint of reducing the difference in thermal expansion coefficients with other components or reducing the difference in thermal expansion coefficients between the crystal and the glass to suppress cracking of the crystalline glass, the average coefficient of thermal expansion from 50 to 350°C is preferably 8.0 ppm / °C or lower, more preferably 7.0 ppm / °C or lower, and even more preferably 6.0 ppm / °C or lower. The average coefficient of thermal expansion from 50 to 350°C can be measured using a differential thermal dilatometer based on the method specified in JIS R3102 (1995). The average coefficient of thermal expansion can be adjusted by the glass composition or crystal content, etc. In addition, this crystalline glass suppresses cracks caused by the difference in thermal expansion rates between the crystalline phase and the glass phase, which in turn tends to increase the average coefficient of thermal expansion to a certain extent.

[0086] (shape)

[0087] The shape of this crystal glass is not particularly limited, and it can be made into various shapes depending on the purpose and application. For example, this crystal glass can be a plate with two opposing main surfaces, or it can be a shape other than a plate, depending on the product and application. More specifically, this crystal glass can be, for example, a flat glass plate without warping, or it can be a curved glass plate with a curved surface. The shape of the main surfaces is also not particularly limited, and it can be formed into various shapes such as circles and quadrilaterals.

[0088] As a preferred shape for this crystalline glass, an example is one having two opposing main faces, with the area of ​​the main faces ranging from 100 to 100,000 cm². 2 Shapes with a thickness of 0.01 to 2 mm.

[0089] From the viewpoint of transmission and reception efficiency when used in antennas, the area of ​​the main surface of this crystal glass is preferably 100 cm². 2 The above, preferably 225cm 2 The above is further optimized to 400cm. 2 That's all. Furthermore, from an operational point of view, the preferred area of ​​the main surface is 100,000 cm². 2 Below, 10000cm is more preferred. 2 The following is a further preferred value: 3600cm 2 the following.

[0090] Furthermore, from the viewpoint of maintaining strength, the thickness of this crystalline glass is preferably 0.01 mm or more, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more. From the viewpoints of making components or articles using this crystalline glass thinner or smaller, and improving production efficiency, the thickness of this crystalline glass is preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.7 mm or less.

[0091] (use)

[0092] This crystalline glass is suitable for use as a circuit board in high-frequency devices (electronic devices) such as semiconductor devices used in communication devices like mobile phones, smartphones, portable information terminals, and Wi-Fi devices; as well as for radar components such as surface acoustic wave (SAW) devices and radar transceivers; and as a substrate for antenna components such as liquid crystal antennas. This crystalline glass exhibits excellent dielectric properties, particularly at high frequencies, and can suppress cracks caused by the difference in thermal expansion rates between the crystalline and glass phases. It also possesses excellent thermal shock resistance, making it suitable for high-frequency substrates and liquid crystal antennas used in high-frequency devices.

[0093] <High-Frequency Substrate>

[0094] This crystalline glass exhibits excellent dielectric properties at high frequencies and excellent thermal shock resistance, making it suitable for use as a substrate for high-frequency applications. The preferred ranges for the relative permittivity, dielectric loss, thermal conductivity, and average coefficient of thermal expansion of the high-frequency substrate (hereinafter also referred to as this high-frequency substrate) in this embodiment using this crystalline glass are the same as those for this crystalline glass.

[0095] High-frequency substrates typically have two opposing main surfaces. From the perspective of transmission and reception efficiency, the area of ​​the main surfaces of this high-frequency substrate is preferably 75 cm². 2 The above, preferably 100cm2 The above is further optimized to 150cm. 2 The above is further optimized to be 300cm. 2 The above is particularly preferred, with 600cm being the ideal size. 2 The above. From the perspective of ensuring strength, the area of ​​the main surface of this high-frequency substrate is preferably 5000 cm². 2 The following applies. As long as the shape has the area described above, it can be freely designed according to its intended use.

[0096] The thickness of the substrate for this high-frequency application is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0.7 mm or less. If the thickness is within the above range, the overall thickness can be made thinner when the substrate is stacked to form the circuit, which is therefore preferable. On the other hand, if the thickness is preferably 0.05 mm or more, more preferably 0.2 mm or more, strength can be ensured.

[0097] When this crystalline glass is used as a high-frequency substrate material, holes can be formed on the crystalline glass substrate made of this crystalline glass. That is, this high-frequency substrate can have holes with openings on at least one of its main surfaces. The holes can be through holes connecting to another main surface, or they can be non-through holes. By filling these holes with conductors or forming conductive films on the hole walls, they can be used as circuits.

[0098] The diameter of the aforementioned hole is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 50 μm or less. On the other hand, the diameter of the hole is preferably 1 μm or more.

[0099] The method for forming the holes is not particularly limited. However, to form small holes with a diameter of 200 μm or less with good precision, a method of irradiating a crystal glass substrate with a laser is preferred, for example. Substrates using this crystal glass exhibit excellent processability after laser irradiation. The wavelength of the laser is not particularly limited; for example, wavelengths of 10.6 μm or less, 3000 nm or less, 2050 nm or less, 1090 nm or less, 540 nm or less, and 400 nm or less can be used. In particular, when forming small holes with a diameter of 100 μm or less, the following two methods are preferred.

[0100] (Processing using UV lasers)

[0101] A hole is formed in a crystalline glass substrate by irradiating it with a UV laser with a wavelength below 400 nm. The UV laser is more preferably pulsed oscillation, and an absorption layer is preferably formed on the surface of the crystalline glass substrate during laser irradiation. After laser irradiation, the crystalline glass substrate can be etched with a solution containing hydrofluoric acid to expand the hole.

[0102] (Processing performed by forming a modified part)

[0103] A modified portion is formed on a crystalline glass substrate by irradiating it with a laser with a wavelength of 400–540 nm, for example, about 532 nm. The crystalline glass substrate is then etched with a solution containing hydrofluoric acid, thereby selectively removing the modified portion and forming a hole. According to this method, the modified portion can be formed with only one pulse of pulsed laser or similar irradiation, resulting in fast hole formation and excellent productivity.

[0104] <Antenna for LCD>

[0105] Liquid crystal antennas are satellite communication antennas that utilize liquid crystal technology to control the direction of transmitted and received radio waves. They are mainly used in transportation vehicles such as ships, airplanes, and automobiles. Liquid crystal antennas are assumed to be used primarily outdoors, therefore requiring stable characteristics over a wide temperature range. In addition, they must be resistant to thermal shocks caused by rapid temperature changes from the ground and the air or by storms in scorching deserts.

[0106] This crystalline glass exhibits excellent dielectric properties at high frequencies and excellent thermal shock resistance, making it suitable for use in liquid crystal antennas. The preferred ranges for the relative permittivity, dielectric loss, thermal conductivity, and average coefficient of thermal expansion of the liquid crystal antenna (hereinafter also referred to as this liquid crystal antenna) in this embodiment using this crystalline glass are the same as those for this crystalline glass.

[0107] A liquid crystal antenna typically has two main surfaces facing each other. From the perspective of transmission and reception efficiency, the area of ​​the main surface of this liquid crystal antenna is preferably 75 cm². 2 The above, preferably 100cm 2 The above is further optimized to 150cm. 2 The above is further optimized to be 300cm. 2 The above is particularly preferred, with 700cm being the ideal size. 2 That's all. From an operational point of view, the preferred area of ​​the main surface of this liquid crystal antenna is 10000 cm². 2 Below, 3600cm is preferred. 2 The following is a further preferred size: 2500cm 2 The following applies. As long as the area is as described above, the shape can be freely designed according to the intended use.

[0108] The thickness of the antenna plate for this liquid crystal is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0.7 mm or less. A plate thickness within the above range allows for a thinner overall structure, which is therefore preferable. On the other hand, a plate thickness of 0.05 mm or more, more preferably 0.2 mm or more, ensures strength.

[0109] <Method for Manufacturing Crystal Glass>

[0110] Next, the manufacturing method of this crystal glass (hereinafter also referred to as the manufacturing method) will be described. The method for manufacturing this crystal glass is not particularly limited; for example, the following method is preferred. The manufacturing method for plate-shaped glass will be described below, but the shape of the glass can be appropriately adjusted according to the purpose.

[0111] This manufacturing method includes: preparing an amorphous glass containing 45-60% SiO2, 20-35% Al2O3, and 9-15% MgO by mass percentage (amorphous glass forming process); and subjecting the amorphous glass to heat treatment (crystallization process). Furthermore, the heat treatment in this manufacturing method includes: precipitating crystals of at least one of hexagonal cordierite and cordierite, such that the Al sites in the aforementioned crystals contain at least one of vacancies and other elements.

[0112] The following details each process.

[0113] (Amorphous glass forming process)

[0114] In this process, amorphous glass is produced by melting and molding raw materials prepared in a manner that forms the desired glass composition. The melting and molding method is not particularly limited; the glass raw materials, prepared by blending the glass raw materials, are placed in a platinum crucible and melted in an electric furnace at 1300°C to 1700°C, and then degassed to homogenize them. The resulting molten glass is poured into a metal mold (e.g., a stainless steel plate) at room temperature and held at the glass transition temperature for approximately 3 hours, then cooled to room temperature to obtain an amorphous glass block. Furthermore, the obtained glass block is processed as needed, such as cutting, grinding, and polishing, to form the desired shape. It should be noted that cutting, grinding, and polishing can be performed after the crystallization process. When processing amorphous glass before the crystallization process, its shape is not particularly limited; the preferred shape is the same as the preferred shape of this crystalline glass.

[0115] Thus, since amorphous glass can be molded into the desired shape from a molten state, it has advantages in terms of ease of molding and ease of large-scale production compared to processes such as ceramics which are formed from powder or slurry and then calcined, or processes such as synthetic quartz which are cut into the desired shape after manufacturing an ingot. In addition, it can be manufactured at a low cost even with the crystallization process described later.

[0116] From the viewpoint of precipitating at least one of hexagonal cordierite and cordierite crystals from crystalline glass, amorphous glass preferably contains 45-60% SiO2, 20-35% Al2O3, and 9-15% MgO. Furthermore, amorphous glass preferably contains 5-15% TiO2 as a nucleation agent. Amorphous glass preferably contains 0.5-15% P2O5 as a vacancy-generating component. It should be noted that the preferred composition of the amorphous glass is the same as the preferred composition of the crystalline glass described above in the section on crystalline glass, and its details are the same as described above.

[0117] (Crystallization process)

[0118] Next, the amorphous glass obtained in the amorphous glass forming process will undergo heat treatment.

[0119] In heat treatment, it is preferable to hold the amorphous glass at a specific processing temperature for a specific time. The processing temperature and holding time are not particularly limited as long as they are conditions that allow at least one of hexagonal cordierite and cordierite to precipitate crystals and that at least one of the Al sites of the aforementioned crystals and other elements to exist.

[0120] The manufacturing method is characterized in that, during heat treatment, at least one of hexagonal cordierite and cordierite crystals is precipitated, and the Al sites of the crystals contain at least one of vacancies and foreign elements.

[0121] There are no particular limitations on the methods for creating vacancies and at least one other element at Al sites. For example, by including components that generate vacancies, such as P₂O₅, in the composition, small phase-separated regions can be formed in the glass in the first temperature region described later, thereby easily creating a portion of Al sites without Al atoms. Alternatively, rapidly increasing the temperature during heat treatment can also easily create a portion of Al sites without Al atoms. These methods can be used individually or in combination.

[0122] The specific preferred conditions for heat treatment are explained below.

[0123] From the viewpoint of promoting the precipitation of hexagonal cordierite / cordierite crystals and from the viewpoint of shortening heat treatment time to improve productivity, the treatment temperature is preferably 960°C or higher, more preferably 980°C or higher, and even more preferably 1000°C or higher. On the other hand, from the viewpoint of suppressing the precipitation of crystals other than hexagonal cordierite / cordierite and from the viewpoint of manufacturability, the treatment temperature is preferably 1350°C or lower, more preferably 1250°C or lower, and even more preferably 1150°C or lower.

[0124] Furthermore, the holding time is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 1.5 hours or more, even more preferably 2 hours or more, particularly preferably 2.5 hours or more, and most preferably 3 hours or more. If the holding time is within the above range, crystallization is sufficiently achieved. On the other hand, since prolonged heat treatment increases the cost of heat treatment, it is preferably 15 hours or less, more preferably 12 hours or less, and particularly preferably 10 hours or less.

[0125] In heat treatment, it is preferable to maintain the treatment temperature as described above, but it may also be further included to raise or lower the temperature within the range of the treatment temperature described above or other temperature ranges.

[0126] Specifically, for example, the temperature can be raised from room temperature to the first temperature zone and held for a certain period of time, and then slowly cooled to room temperature. Alternatively, a two-stage heat treatment can be selected, namely, raising the temperature from room temperature to the first temperature zone and holding it for a certain period of time, then holding it in a second temperature zone that is higher than the first temperature zone for a certain period of time, and then slowly cooling it to room temperature.

[0127] Especially when the composition contains components that generate nuclei and vacancies, the heat treatment preferably includes two stages: holding in a first temperature region and holding in a second temperature region. In the two-stage heat treatment, by holding in the first temperature region, nuclei that serve as the starting point for the growth of hexagonal cordierite / cordierite crystals can be generated using the nuclei generated in the amorphous glass. Then, by holding in the second temperature region, hexagonal cordierite / cordierite crystals grow from these nuclei. Although hexagonal cordierite / cordierite crystals will also grow through a single-stage heat treatment, nucleation before crystal growth makes it easier for crystals to exist uniformly in the crystalline glass and for Al sites to form regions without Al atoms. Furthermore, when the amorphous glass contains components that generate vacancies, the vacancy-generating components cause minor phase separation during heat treatment, and the crystal grows from the interface of these phase separations, making it easier for Al sites to form regions without Al atoms.

[0128] When performing a two-stage heat treatment, the first temperature region is preferably a temperature region where the rate of crystal nucleation in the glass composition increases. Specifically, the first temperature region is preferably 760°C or higher, more preferably 800°C or higher, and even more preferably 850°C or higher. Furthermore, the first temperature region is preferably 960°C or lower, more preferably 920°C or lower, and even more preferably 880°C or lower.

[0129] Furthermore, the holding time in the first temperature region is preferably 0.5 hours or more, more preferably 1 hour or more, even more preferably 1.5 hours or more, and particularly preferably 2 hours or more. If the holding time is within the above range, nucleation can be easily and sufficiently carried out. On the other hand, from the viewpoint of suppressing crystal growth while nucleation is being carried out, and from the viewpoint of improving the overall dielectric properties of the crystal glass, the holding time is preferably 5 hours or less, more preferably 4 hours or less, and particularly preferably 3 hours or less.

[0130] The second temperature region is preferably a temperature region where the crystal growth rate of hexagonal cordierite / cordierite crystals increases. Specifically, the second temperature region is preferably 960°C or higher, more preferably 980°C or higher, and even more preferably 1000°C or higher. In addition, the second temperature region is preferably 1350°C or lower, more preferably 1250°C or lower, and even more preferably 1150°C or lower.

[0131] Furthermore, the holding time in the second temperature region is preferably 0.5 hours or more, more preferably 1 hour or more, further preferably 1.5 hours or more, even more preferably 2 hours or more, particularly preferably 2.5 hours or more, and most preferably 3.0 hours or more. If the holding time is within the above range, crystal growth can be easily and sufficiently carried out. On the other hand, from a manufacturability point of view, the holding time is preferably 15 hours or less, more preferably 14 hours or less, and particularly preferably 12 hours or less.

[0132] There is no particular limitation on the heating rate during heat treatment, which is generally 5°C / min or higher. From the viewpoint that accelerating the heating rate will result in the presence of at least one of vacancies and foreign elements at the Al sites, it is preferable to be 15°C / min or higher, and more preferably 20°C / min or higher.

[0133] On the other hand, if the heating rate is preferably 30°C / min or less, more preferably 25°C / min or less, cracks caused by the difference in thermal expansion coefficients between the glass phase and the crystalline phase that occur during heating can be suppressed.

[0134] There is no particular limitation on the cooling rate, but it is preferably 10°C / min or less, more preferably 5°C / min or less, and even more preferably 1°C / min or less. This can suppress the warping of the crystalline glass and the cracks caused by the difference in thermal expansion rates between the amorphous and crystalline phases during cooling. On the other hand, the cooling rate is generally 0.5°C / min or more.

[0135] Example

[0136] The following examples illustrate the present invention in detail, but the invention is not limited thereto. Examples 1-8, 11-13, and 15-18 are examples, and Examples 9, 10, and 14 are comparative examples.

[0137] The glass raw materials were prepared in accordance with the composition shown in Table 1, expressed as a molar percentage based on oxides, and weighed to produce 400g of glass. Next, the mixed raw materials were placed in a platinum crucible and melted in an electric furnace at 1500–1700°C for approximately 3 hours, followed by degassing to homogenize the mixture. The components shown in Table 1 are expressed as mass percentages in Table 2.

[0138] The molten glass obtained is poured into a metal mold and held at a temperature approximately 50°C higher than the glass transition temperature for 1 hour. Then, it is cooled to room temperature at a rate of 0.5°C / min to obtain a glass block. The obtained glass block is cut, ground, and finally mirror-polished on both sides to obtain glass 1 to 12 in the form of glass plates of 40mm × 40mm and 2mm thickness.

[0139] The obtained glass is subjected to the following process: Figure 1 Heat treatment. Figure 1 This is a diagram schematically illustrating the temperature changes during two stages of heat treatment. Specifically, Figure 1 The diagram illustrates a heat treatment process in which amorphous glass is heated to a temperature T1 at a first heating rate, held for a holding time t1, then heated to a temperature T2 at a second heating rate, held for a holding time t2, and subsequently cooled.

[0140] Will Figure 1 The specific temperature and other conditions for heat treatment were shown in Table 3, thereby obtaining a crystalline glass. Furthermore, the physical properties described in Table 3 were obtained from the obtained crystalline glass. It should be noted that in Table 3, an empty column “-” in the “Crystallization Conditions” column indicates that heat treatment under those conditions was not performed, and an empty column “-” in the “Properties” column indicates that the physical property was not measured.

[0141] The methods for determining each property are shown below.

[0142] (XRD determination, Ritwald analysis)

[0143] (Sample preparation conditions for XRD determination)

[0144] The powder for XRD determination was obtained by crushing a heat-treated crystalline glass plate using an agate mortar and pestle.

[0145] (XRD measurement conditions)

[0146] X-ray diffraction was measured under the following conditions to identify the precipitated crystals. The identification of crystal types used diffraction peak patterns included in the ICSD Inorganic Crystal Structure Database and the ICDD Powder Diffraction Database.

[0147] Measurement apparatus: SmartLab manufactured by Rigaku Corporation

[0148] Determination method: Centralized method

[0149] Tube voltage: 45kV

[0150] Tube current: 200mA

[0151] Using X-rays: CuKα rays

[0152] Measurement range: 2θ = 10°~80°

[0153] Speed: 10° / minute

[0154] Step: 0.02°

[0155] (Ritterwald determined sample preparation conditions)

[0156] After the crystalline glass powder used in the XRD determination is passed through a 500 μm sieve, ZnO, as a standard substance, is added at 10 wt% of the total sample.

[0157] (Ritwald's analytical conditions)

[0158] Powder X-ray diffraction was measured under the following conditions, and the results were used for Rietwald analysis.

[0159] Measurement apparatus: SmartLab manufactured by Rigaku Corporation

[0160] Determination method: Centralized method

[0161] Tube voltage: 45kV

[0162] Tube current: 200mA

[0163] Using X-rays: CuKα rays

[0164] Measurement range: 2θ = 10°~90°

[0165] Speed: 5° / minute

[0166] Step: 0.01°

[0167] The powder X-ray diffraction patterns obtained under the above conditions were analyzed using the Rietan FP analytical procedure. The analysis of each sample was optimized so that the Rwp (representing the quality of convergence) was less than 10. The Rietan FP method is described in the "Crystallization Analysis Handbook" (Kyoritsu Publishing, 1999, pp. 492-499), edited by the Editorial Committee of the "Crystallization Analysis Handbook" of the Japanese Crystallography Society.

[0168] (Calculation of crystallization rate)

[0169] The content (crystallization rate) of hexagonal cordierite / cordierite crystals in the crystallized glass was calculated as follows: the weight ratio of the crystalline phase obtained by Rietwald analysis to the remaining glassy phase obtained by subtracting the crystalline phase content from the total sample volume, minus the added 10 wt% ZnO, was used to calculate the remaining phase content as 100 wt%. It should be noted that the "Total Content of Hexagonal Cordierite / Cordierite Crystals" in Table 3 below records the percentage (mass%) of the total content of hexagonal cordierite / cordierite crystals.

[0170] (Calculation of vacancy rate)

[0171] The vacancy rate, i.e., the proportion of the total number of sites where no Al atoms are present relative to the Al sites, is calculated using the Al atom occupancy rate obtained through Rietwald analysis.

[0172] (Average coefficient of thermal expansion)

[0173] The determination was performed using a differential thermal dilatometer, based on the method specified in JIS R3102 (1995). The measurement temperature range was 50–350 °C, and the units are expressed as ppm / °C. As samples, circular (cylindrical) samples were prepared from heat-treated crystallized glass plates, each 5 mm in diameter and 20 mm in thickness.

[0174] (thermal conductivity)

[0175] The thermophysical properties were measured using a laser flash thermophysical property measuring apparatus (Kyoto Electronics Industries, Ltd. LFA-502) according to the method specified in JIS R1611 (2010). The measurement temperature was 20°C. A circular sample with a diameter of 5 mm and a thickness of 1 mm was used, prepared from a heat-treated crystallized glass plate.

[0176] (Relative permittivity ε', dielectric loss tangent tanδ)

[0177] The obtained amorphous and crystalline glass were processed into cubes with a length of 30.0 mm, a width of 30.0 mm, and a thickness of 0.5 mm. The 30.0 mm × 30.0 mm facets were then polished to a mirror finish. The relative permittivity ε' and dielectric loss tangent tanδ at 20 °C and 10 GHz were determined using a network analyzer via the split column dielectric resonance method (SPDR).

[0178] (Sample status)

[0179] For each crystal glass in Examples 1-18, five samples were used to evaluate the fragility of the samples according to the following criteria. The samples were confirmed by visual inspection, and even the slightest crack was considered a sign of fragility.

[0180] A: The number of samples that broke after heat treatment was less than 1 out of every 5.

[0181] B: The number of samples that broke after heat treatment was 2 to 3 out of every 5.

[0182] C: The number of samples that broke after heat treatment was more than 4 out of every 5.

[0183] [Table 1]

[0184]

[0185] [Table 2]

[0186]

[0187] [Table 3]

[0188]

[0189] The crystalline glasses obtained using glasses 1-7 and 9-12 as examples (Examples 1-8, 11-13, and 15-18) did not break or were not easily broken after heat treatment. These samples could be further processed for property testing, and the content of hexagonal cordierite / cordierite crystals was 40% by mass or more. It should be noted that the crystalline glass of Example 15 was less prone to breakage than the crystalline glasses of Examples 11-13. Therefore, the sample state of Example 15 is marked as B+ in Table 3.

[0190] In addition, in the crystalline glasses of Examples 2 to 4, 6, 7 and 12, the content of hexagonal cordierite / cordierite crystals is more than 40% by mass, and the average thermal expansion coefficient at 50 to 350°C is more than 1 ppm, and the thermal conductivity at 20°C is more than 1.0 W / (m·K).

[0191] Furthermore, the crystal glasses of Examples 2, 3, 4, 6, 7, 11, 12, 16, 17, and 18, which are examples of embodiments, further have a relative permittivity of 7 or less and a dielectric loss tangent of 0.003 or less at 20°C and 10 GHz, which are good values, confirming that they have good radio wave transmittance.

[0192] On the other hand, regarding the crystalline glass of Example 9, due to the low heat treatment temperature, sufficient crystallization did not occur, resulting in a low crystallization rate. Regarding the crystalline glass of Example 10, due to the short heat treatment time, sufficient crystallization did not occur, resulting in a low crystallization rate. Regarding Example 14, due to the excessive proportion of P, the amount of hexagonal cordierite / cordierite crystals precipitated decreased. Furthermore, in the crystalline glass of Example 14, a large amount of crystals other than hexagonal cordierite / cordierite crystals precipitated, resulting in the sample being prone to cracking after heat treatment.

[0193] The present invention has been described in detail with reference to specific embodiments, but those skilled in the art will understand that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2020-157712, filed on September 18, 2020, the contents of which are incorporated herein by reference.

[0194] Industrial availability

[0195] The crystalline glass of this invention exhibits excellent dielectric properties for high-frequency signals and demonstrates high thermal shock resistance.

[0196] Such crystal glass is very useful as a substrate for high-frequency electronic devices, such as those for handling high-frequency signals above 10 GHz, especially high-frequency signals above 30 GHz, and even higher high-frequency signals above 35 GHz; as well as for components such as liquid crystal antennas used in environments with large temperature variations; and for devices that use lasers or other methods to perform hole-making processes.

Claims

1. A crystalline glass containing crystals of at least one of hexagonal cordierite and orthorhombic cordierite. The total amount of the crystals is more than 40% by mass of the crystallized glass. The crystal contains at least one of vacancies and foreign elements at the Al sites. The crystal glass contains, by mass percentage based on oxides, 45-60% SiO2, 20-35% Al2O3, 9-15% MgO, more than 8% and less than 15% TiO2, 1.5-9% P2O5, and 0% B2O3.

2. The crystal glass according to claim 1, wherein, The total portion including at least one of the vacancy and the heteroelement is more than 4 atom% of the site of A1.

3. The crystal glass according to claim 1 or 2, wherein, The crystal glass has opposing main faces, the area of ​​which is 100 to 100,000 cm². 2 The thickness is 0.01 to 2 mm.

4. The crystal glass according to claim 1 or 2, wherein, The thermal conductivity at 20℃ is above 1.0 W / (m·K).

5. The crystal glass according to claim 1 or 2, wherein, The relative permittivity at 20℃ and 10GHz is below 7.

6. The crystal glass according to claim 1 or 2, wherein, The dielectric loss tangent at 20℃ and 10GHz is below 0.

003.

7. The crystal glass according to claim 1 or 2, wherein, The average coefficient of thermal expansion between 50 and 350°C is above 1 ppm / °C.

8. A high-frequency substrate using the crystal glass according to any one of claims 1 to 7.

9. A liquid crystal antenna using the crystal glass according to any one of claims 1 to 7.

10. A method for manufacturing the crystal glass according to claim 1, comprising: Prepare an amorphous glass, expressed as an oxide-based mass percentage, containing 45–60% SiO2, 20–35% Al2O3, 9–15% MgO, greater than 8% and less than 15% TiO2, 1.5–9% P2O5, and 0% B2O3, and... The amorphous glass is heat-treated; The heat treatment includes holding the amorphous glass at a temperature above 960°C for at least 0.5 hours. The heat treatment includes: precipitating at least one of hexagonal cordierite and orthorhombic cordierite crystals, such that the Al sites of the crystals contain at least one of vacancies and other elements.

11. The method for manufacturing crystal glass according to claim 10, wherein, The amorphous glass has opposing main surfaces, the area of ​​which is 100 to 100,000 cm². 2 The thickness of the amorphous glass is 0.01 to 2 mm.

12. The method for manufacturing crystal glass according to claim 10 or 11, wherein, The heat treatment includes holding in a first temperature region and holding in a second temperature region, wherein the first temperature region is 760°C to 960°C, and the holding time in the first temperature region is 0.5 hours or more. The second temperature range is 960℃ to 1350℃, and the holding time in the second temperature range is more than 0.5 hours.

Images