Glass ceramics with specific thermal expansion properties

Abstract

The invention relates to glass ceramics having an improved thermal expansion behavior and to the use thereof in precision parts.

Description

This application is a divisional application of patent application 202210252035.9 filed on March 15, 2022, with the invention name “Glass ceramics with specific thermal expansion properties”. Technical Field

[0001] The invention relates to a glass ceramic having a specific thermal expansion behavior and good melting properties, forming properties and ceramicization properties; and to the use of the glass ceramic according to the invention in precision components. Background Art

[0002] Materials and precision components with low thermal expansion or low CTE (Coefficient of Thermal Expansion) are known in the art.

[0003] Ceramics, titanium-doped quartz glass and glass ceramics are known as precision component materials with low thermal expansion in the temperature range around room temperature. Glass ceramics with low thermal expansion are especially lithium aluminum silicate glass ceramics (LAS glass ceramics), which are described, for example, in US 4,851,372, US 5,591,682, EP 587979A, US 7,226,881, US 7,645,714, DE102004008824 A, DE 102018111144 A. Other materials for precision components are cordierite ceramics or cordierite glass ceramics.

[0004] Such materials are often used for precision components that must meet particularly stringent requirements regarding their properties (e.g. mechanical, physical, optical properties). They are used in particular in terrestrial and space-based astronomy and Earth observation, LCD lithography, microlithography and EUV lithography, metrology, spectroscopy and measurement technology. In this case, it is required that the components have a particularly low thermal expansion, depending on the specific application.

[0005] Usually, the thermal expansion of a material is determined by a static method, in which the length of the test piece is determined at the beginning and end of a certain temperature interval and the average expansion coefficient α or CTE (coefficient of thermal expansion) is calculated from the length difference. The CTE is then designated as the average value for the temperature interval, for example CTE (0; 50) or α (0; 50) for a temperature interval of 0°C to 50°C.

[0006] In order to meet the growing demand, materials have been developed with a CTE that is better adapted to the application field of the components formed by the material. For example, the average CTE can be optimized not only for the standard temperature interval CTE (0; 50), but also for example for a temperature interval near the actual application temperature, such as the interval from 19°C to 25°C, i.e. CTE (19; 25) for certain lithography applications. In addition to determining the average CTE, the thermal expansion of the test piece can also be determined in a very small temperature interval and thus represented by a CTE-T curve. Preferably, such a CTE-T curve can have a zero crossing at one or more temperatures, preferably at or close to the expected application temperature. At the zero crossing of the CTE-T curve, the relative length change with temperature is particularly small. For some glass-ceramics, the zero crossing of this CTE-T curve can be transferred to the application temperature of the component by appropriate temperature treatment. In addition to the absolute CTE value, the slope of the CTE-T curve near the application temperature should also be as small as possible so that the length change of the component is as small as possible when a small temperature change occurs. For these special zero-expansion glass-ceramics, the above-mentioned optimization of CTE or thermal expansion is achieved by varying the ceramizing conditions while keeping the composition constant.

[0007] In the case of known precision components and materials, in particular in the case of glass ceramics such as LAS glass ceramics, one adverse effect is the so-called "thermal hysteresis", hereinafter referred to as "hysteresis". Hysteresis refers to the difference between the change in length of a test piece when it is heated at a constant heating rate and the change in length of the test piece when it is subsequently cooled at a constant cooling rate, even if the cooling rate and the heating rate are the same in magnitude. If the change in length is displayed graphically as a function of the temperature used for heating or cooling, a classic hysteresis loop results. The shape of the hysteresis loop also depends on the rate of temperature change. The faster the temperature change, the more pronounced the hysteresis effect. The hysteresis effect clearly shows that the thermal expansion of LAS glass ceramics depends on temperature and time, i.e., for example, on the rate of temperature change, which has also been described in the specialist literature elsewhere, for example O. Lindig and W. Pannhorst, "Glass Ceramics: Thermal Insulation and Thermal Properties of Glass Ceramics". Thermal expansion and length stability as a function of temperature and time”, Applied Optics, Vol. 24, No. 20, October 1985; R. Haug et al., “Glass-ceramics Length variation in the temperature range -60°C to +100°C”, Applied Optics, Vol. 28, No. 19, October 1989; R. Jedamzik ​​et al., “Glass-ceramics Modeling of thermal expansion behavior at arbitrary temperature profiles 7739, 2010; D.B. Hall, “Dimensional stability of several low expansion glass-ceramics over time and temperature,” Applied Optics, Vol. 35, No. 10, April 1996.

[0008] Since the length change of glass ceramics exhibiting thermal hysteresis lags or leads the temperature change, the material or precision components made of it exhibit a disruptive isothermal length change, i.e. after a temperature change, the length change of the material still occurs when the temperature has been kept constant (so-called "isothermal holding") and until a steady state is reached. The same effect reappears when the material is subsequently heated and cooled again.

[0009] For the LAS glass-ceramics known to date, it has not been possible to eliminate the thermal hysteresis effect without affecting the other properties, despite varying the ceramizing conditions while keeping the composition constant.

[0010] Regarding the properties of materials, especially glass ceramics, for precision components, it is usually relevant to have a temperature range of 0°C to 50°C, especially 10°C to 35°C or 19°C to 25°C, wherein a temperature of 22°C is usually referred to as room temperature. Since many applications of precision components occur in a temperature range of greater than 0°C to room temperature, materials with thermal hysteresis effects and isothermal length changes are disadvantageous, since optical interference may occur in optical components such as lithography mirrors and astronomical or space-based mirrors. This may lead to inaccurate measurements of other precision components made of glass ceramics used in measurement technology (e.g. precision measuring rods, reference plates in interferometers).

[0011] Some well-known materials such as ceramics, titanium-doped quartz glass and some glass-ceramics have an excellent accuracy of 0±0.1x10 -6 / K (corresponding to 0±0.1 ppm / K) with an average coefficient of thermal expansion CTE (0; 50). Materials with such a low average CTE in the temperature range mentioned are referred to as zero expansion materials within the meaning of the present invention. However, glass ceramics, in particular LAS glass ceramics, whose average CTE is optimized in this way, usually have thermal hysteresis in a temperature range of 10°C to 35°C. This means that these materials will experience disturbing hysteresis effects, especially in applications at room temperature (i.e. 22°C), which will impair the accuracy of precision parts made of such materials. Therefore, a glass ceramic material has been developed (see US 4,851,372), which has no obvious hysteresis at room temperature, but the effect is not eliminated, but only transferred to lower temperatures, so that this glass ceramic shows obvious hysteresis at temperatures of 10°C and below, which may still be disturbing. In order to characterize the thermal hysteresis properties of a material in a specific temperature range, the thermal behavior of the material is therefore observed at different temperature points within this range within the scope of the present invention. There are even glass-ceramics which do not show any significant hysteresis at 22°C and 5°C, but these glass-ceramics have an average CTE (0;50) > 0 ± 0.1 ppm / K and are therefore not zero-expansion glass-ceramics in the sense defined above.

[0012] Another requirement for glass-ceramic materials is good solubility of the glass components and easy melting and homogenization of the initial glass melt in large-scale production facilities so that after the glass is ceramicized, the high requirements placed on the glass-ceramic in terms of CTE uniformity, internal quality - especially the small number of inclusions (especially bubbles), low streak level - and polishability are met. Purpose of the Invention

[0013] The object of the present invention is therefore to provide a glass ceramic with improved expansion behavior. Another object is to provide a glass ceramic that can be mass-produced, in particular in the temperature range of 10° C. to 35° C., with zero expansion and reduced thermal hysteresis, and precision components made of this material.

[0014] The above objects are achieved by the subject matter of the patent claims. The invention has different aspects:

[0015] According to one aspect of the present invention, a LAS glass ceramic is provided, which has a maximum temperature of 0±0.1x 10 -6 / K and a thermal hysteresis of <0.1 ppm at least in the temperature range of 10-35 °C, and comprises the following components (in Mol % based on oxides): SiO2 60–71 Li2O 7–9.4 MgO+ZnO 0–<0.6 At least one component selected from the group consisting of P2O5, R2O, RO, wherein R2O may be Na2O and / or K2O and / or Cs2O and / or Rb2O, and RO may be CaO and / or BaO and / or SrO, a nucleating agent with a content of 1.5 to 6 Mol%, wherein the nucleating agent is at least one component selected from the group consisting of TiO2, ZrO2, Ta2O5, Nb2O5, SnO2, MoO3, WO3.

[0016] According to a further aspect, the invention relates to the use of the glass ceramic according to the invention as a substrate for a precision component.

[0017] According to a further aspect, the invention relates to the use of the LAS glass-ceramic according to the invention in precision components, in particular for use in metrology, spectroscopy, measuring technology, lithography, astronomy or Earth observation from space, for example as mirrors or mirror carriers for segmented or integral astronomical telescopes, or also as reduced-weight or ultra-light mirror substrates, for example for space-based telescopes, or as high-precision structural components for distance measurement, for example in optics in space or for Earth observation, as precision components, for example standards for precise measuring technology, precision measuring rods, reference plates in interferometers, as mechanical precision components, for example for ring laser gyroscopes, helical springs for watchmaking, for example as mirrors and prisms in LCD lithography, for example as mask holders, wafer stages, reference plates, reference frames and grid plates in microlithography and EUV (extreme ultraviolet) microlithography in which reflective optics are used, and as mirrors and / or photomask substrates or photomask blanks in EUV microlithography.

[0018] According to a further aspect, the invention relates to a precision component comprising the LAS glass ceramic according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the attached figure:

[0020] Figure 1 The CTE-T curve of a material known from the prior art with low thermal expansion, for example for precision components, is shown.

[0021] Figure 2 The hysteresis behavior of three glass ceramic samples determined using the same method as used in the present invention is shown. This figure is from R. Jedamzik ​​et al., "Glass Ceramics Modeling of Thermal Expansion Behavior at Arbitrary Temperature Profiles”, Proc. SPIE, Vol. 7739, 2010.

[0022] Figures 3 to 8Hysteresis curves are shown for known glass-ceramic materials which can be used to manufacture known precision components and which have a thermal hysteresis of >0.1 ppm at least in the temperature range 10-35°C (dashed line = cooling curve, dots = heating curve).

[0023] Fig. 9 The hysteresis curve of a prior art glass ceramic is shown (dashed line = cooling curve, dots = heating curve), which can be used to manufacture precision components and has a thermal hysteresis of <0.1 ppm at least in the temperature range of 10-35°C. However, the steep curve shows that the glass ceramic is not zero expansion.

[0024] Fig.10 and 11 Hysteresis curves of glass ceramics according to the invention (according to the composition of Examples 6 and 7 in Table 1) are shown, which can be used to manufacture precision components according to the invention and which have a thermal hysteresis of <0.1 ppm at least in the temperature range of 10-35°C (dashed line = cooling curve, dots = heating curve).

[0025] Fig.12 and Fig.13 The standardized Δl / l0-T curve (also called dl / l0 curve) of the glass ceramic according to the invention (according to the composition of Examples 6 and 7 in Table 1) and an auxiliary line for determining the parameter F as a measure of the flatness of the expansion curve in the temperature range of 0°C to 50°C are shown.

[0026] Figures 14 to 17 Standardized Δl / l0-T curves are shown for known materials that can be used to manufacture known precision components, as well as auxiliary lines for determining the parameter F as a measure of the flatness of the expansion curve in the temperature range of -20°C or -10°C to 70°C or 80°C.

[0027] Fig.18 Shows Fig.12 and 13 Normalized Δl / l0-T curves of glass ceramics in the temperature range of -30°C to +70°C.

[0028] Fig.19 Normalized Δl / l0-T curves for known materials in the temperature range of -30°C to +70°C are shown.

[0029] Fig. 20 and 21 Shows Fig.12 and 13 The CTE-T curve of glass-ceramics that can be used to produce advantageously precise components advantageously has a CTE "plateau".

[0030] Fig. 22 and Fig.23 Shown from Fig.24 and Fig.25 The slope of the CTE-T curve.

[0031] Fig.24 and 25 Different CTE curves are shown for two examples of the invention, which are set by different ceramization parameters.

[0032] Fig.26 The slope of the CTE-T curve of the glass ceramic according to the present invention having the composition according to Example 7 in Table 1 is shown.

[0033] Fig. 27 The normalized Δl / 10-T curve of the glass ceramic according to the invention (according to the composition of Example 17 in Table 1) and the alternative parameter f for determining the flatness of the expansion curve in the temperature range of 20°C to 40°C are shown. (20；40) Auxiliary lines.

[0034] Fig.28 Shows Shows Fig.13 Standardized Δl / 10-T curves of glass ceramics and for determining the alternative parameter f as a measure of the flatness of the expansion curve in the temperature range from -10°C to 30°C (-10；30) Auxiliary lines.

[0035] Fig.29 Shows Shows Fig.13 Standardized Δl / 10-T curves of glass ceramics and for determining the alternative parameter f as a measure of the flatness of the expansion curve in the temperature range from 20°C to 70°C (20；70) Auxiliary lines.

[0036] Fig.30 The normalized Δl / 10-T curve of the glass ceramic according to the invention (according to the composition of Example 14 in Table 1) and the alternative parameter f for determining the flatness of the expansion curve in the temperature range of -10°C to 30°C are shown. (-10；30) Auxiliary lines. DETAILED DESCRIPTION

[0037] The subject of the present invention is a LAS glass ceramic having a maximum temperature of 0±0.1×10 -6 / K and a thermal hysteresis of <0.1 ppm at least in the temperature range of 10-35 °C, and comprises the following components (in Mol % based on oxides): SiO2 60–71 Li2O 7–9.4 MgO+ZnO 0–<0.6 At least one component selected from the group consisting of P2O5, R2O, RO, wherein R2O may be Na2O and / or K2O and / or Cs2O and / or Rb2O, and RO may be CaO and / or BaO and / or SrO, a nucleating agent with a content of 1.5 to 6 Mol%, wherein the nucleating agent is at least one component selected from the group consisting of TiO2, ZrO2, Ta2O5, Nb2O5, SnO2, MoO3, WO3.

[0038] The present invention provides for the first time a LAS glass ceramic (hereinafter also referred to as glass ceramic) which combines a number of relevant properties: its average coefficient of thermal expansion CTE in the range of 0 to 50°C is up to 0±0.1×10 -6 / K, i.e. it is zero expansion. In addition, it has a thermal hysteresis of <0.1ppm at least in the temperature range of 10°C to 35°C. Materials with a low hysteresis effect of <0.1ppm in the temperature range are referred to as "hysteresis-free" hereinafter. Since, as mentioned above, the form of the hysteresis depends on the temperature change rate used to determine the hysteresis, the statements about hysteresis within the scope of the present invention relate to a heating / cooling rate of 36K / h, i.e. 0.6K / min. In an advantageous embodiment, the LAS glass ceramic may have no hysteresis at least in the temperature range of 5°C to 35°C or at least 5°C to 40°C, advantageously at least in the temperature range of >0°C to 45°C, preferably at least in the temperature range of -5°C to 50°C.

[0039] The following is a detailed introduction to CTE and thermal hysteresis characteristics.

[0040] According to the present invention, glass ceramics are understood to mean inorganic non-porous materials with a crystalline phase and a glass phase, wherein the matrix, i.e. the continuous phase, is usually a glass phase. In order to manufacture glass ceramics, the components of the glass ceramics are first mixed, melted and clarified, and then cast into so-called green glass (Grünglas). After cooling, the green glass is crystallized in a controlled manner by reheating (so-called "controlled volume crystallization"). The chemical composition (analysis) of green glass and the glass ceramics made therefrom is the same, and ceramicization only changes the internal structure of the material. Therefore, when the composition of glass ceramics is discussed below, the above content also applies to the precursor of the glass ceramics, i.e. green glass.

[0041] The inventors have recognized for the first time that the components MgO and ZnO promote the occurrence of thermal hysteresis in the temperature range under consideration, and therefore that it is necessary to limit the content of MgO and ZnO in order to provide a hysteresis-free, zero-expansion LAS glass-ceramic at least in the temperature range of 10° C. to 35° C., as described in the claims. In contrast, the starting point previously was that these glass components in combination or separately in a zero-expansion LAS glass-ceramic were necessary in order to achieve zero expansion and a "flat" CTE-T curve of the material, i.e. a low CTE-T curve slope in the relevant temperature range. Thus, a conflict of objectives arises in terms of the LAS glass-ceramic being able to be zero-expansion or hysteresis-free.

[0042] If not only MgO and ZnO are avoided substantially, but also SiO is selected from the scope specified by the present invention and the content of Li O is selected, so the present invention solves this conflict of objectives. It is found within the scope of the present invention that within the specified scope of SiO (60-71 Mol%) and Li O (7-9.4 Mol%), zero expansion and hysteresis-free glass ceramics can be surprisingly obtained.

[0043] LAS glass ceramics contain a negative expansion crystalline phase, which within the scope of the invention advantageously comprises or consists of a high quartz mixed crystal (also referred to as β-eucryptite and a positive expansion glass phase. In addition to SiO2 and Al2O3, Li2O is the main component of the mixed crystal. If present, ZnO and / or MgO are also incorporated into the mixed crystal and influence the expansion behavior of the crystalline phase together with Li2O. This means that the above-mentioned provisions according to the invention (reduction, preferably exclusion of MgO and ZnO) have a significant influence on the type and properties of the mixed crystal formed during the ceramicization process. Compared with the known zero expansion glass Compared to glass ceramics, in which MgO and ZnO are used in particular to adjust the desired expansion behavior of the glass ceramic, at least one component selected from the group which can consist of P2O5, R2O, RO is used for this purpose within the scope of the invention, wherein R2O can be Na2O and / or K2O and / or Cs2O and / or Rb2O, and RO can be CaO and / or BaO and / or SrO. However, in contrast to MgO and ZnO, the above-mentioned alkaline earth metal oxides and alkali metal oxides (if present) remain in the glass phase and are not incorporated into the high quartz mixed crystal.

[0044] It is found within the scope of the present invention that it is advantageous to provide a zero expansion and hysteresis-free glass ceramic if the composition satisfies the condition molar content SiO2+(5x molar content Li2O)≥106 or preferably ≥106.5, preferably molar content SiO2+(5x molar content Li2O)≥107 or ≥107.5. Alternatively or additionally, an advantageous upper limit of ≤115.5 or ≤114.5 or ≤113.5 may be applied to the condition "molar content SiO2+(5x molar content Li2O)".

[0045] In an advantageous development, the glass ceramic may contain the following components in mol %, alone or in any combination:

[0046] In an advantageous development, the glass ceramic may contain the following components in mol %, alone or in any combination:

[0047] Furthermore, preferably, in the glass ceramic within the above-mentioned limit range, the sum of R2O, RO and TiO2+ZrO2 may contain the following components in Mol% individually or in any combination:

[0048] In an advantageous embodiment, the LAS glass-ceramic comprises (in Mol % based on oxides): The nucleating agent is preferably TiO2 and / or ZrO2.

[0049] In an advantageous embodiment, the LAS glass-ceramic comprises (in Mol % based on oxides): The nucleating agent is preferably TiO2 and / or ZrO2.

[0050] In a further advantageous embodiment, the LAS glass ceramic comprises (in Mol % based on oxides): The nucleating agent is preferably TiO2 and / or ZrO2.

[0051] The glass ceramic contains silicon dioxide (SiO2) with a content of at least 60Mol%, more preferably at least 60.5Mol%, also preferably at least 61Mol%, also preferably at least 61.5Mol%, and more preferably at least 62.0Mol%. The content of SiO2 is up to 71Mol% or less than 71Mol%, more preferably up to 70Mol% or less than 70Mol%, more preferably up to 69Mol%, and also preferably up to 68.5Mol%. Mixtures with a larger content of SiO2 are more difficult to melt and the viscosity of the melt is higher, which may lead to homogenization problems of the melt in large-scale production facilities. Therefore, a content of 71Mol%, preferably 70Mol%, should not be exceeded. If the viscosity of the melt is high, the processing temperature Va of the melt increases. The clarification and homogenization of the melt require very high temperatures, but this causes the lining (Auskleidung) of the melting unit to be attacked by the corrosiveness of the melt, which increases with the increase of temperature. In addition, even higher temperatures may not be sufficient to produce a uniform melt, with the result that the green glass may have streaks and inclusions (particularly bubbles and particles from the lining of the melting unit), which, after ceramicization, do not meet the uniformity requirements of the produced glass-ceramic properties, such as the uniformity of the coefficient of thermal expansion. Lower SiO2 content may be preferred as the upper limit for this reason.

[0052] The content of Al2O3 is advantageously at least 10 Mol%, preferably at least 11 Mol%, preferably at least 12 Mol%, more preferably at least 13 Mol%, further preferably at least 14 Mol%, further preferably at least 14.5 Mol%, more preferably at least 15 Mol%. If the content is too low, no or too little low-expansion mixed crystals are formed. The proportion of Al2O3 is advantageously at most 22 Mol%, preferably at most 21 Mol%, preferably at most 20 Mol%, further preferably at most 19.0 Mol%, more preferably at most 18.5 Mol%. Too high a content of Al2O3 leads to an increase in viscosity and promotes uncontrolled devitrification of the material.

[0053] The glass ceramic according to the present invention may contain 0 to 6 mol% of P2O5. The phosphate content P2O5 of the glass ceramic may advantageously be at least 0.1 mol%, preferably at least 0.3 mol%, preferably at least 0.5 mol%, also preferably at least 0.6 mol%, more preferably at least 0.7 mol%, more preferably at least 0.8 mol%. P2O5 is substantially embedded in the crystalline phase of the glass ceramic and has a positive effect on the expansion behavior of the crystalline phase and thus the expansion behavior of the glass ceramic. In addition, the melting of the components and the clarification behavior of the melt are improved. However, if the P2O5 content is too much, the trend of the CTE-T curve in the temperature range from 0°C to 50°C does not show a favorable flat trend. Therefore, advantageously, a maximum of 6 mol%, preferably a maximum of 5 mol%, more preferably a maximum of 4 mol%, more preferably less than 4 mol% of P2O5 is contained in the glass ceramic. According to various embodiments, the glass ceramic may be free of P2O5.

[0054] Within the scope of the present invention, certain sums and ratios of the components SiO 2 , Al 2 O 3 and / or P 2 O 5 , ie the components which form high quartz mixed crystals, are advantageous for forming the glass ceramic according to the invention.

[0055] The total proportion in mol% of the basic components of the LAS glass ceramic, SiO2 and Al2O3, is advantageously at least 75 mol%, preferably at least 78 mol%, preferably at least 79 mol%, more preferably at least 80 mol% and / or preferably up to 90 mol%, preferably up to 87 mol%, preferably up to 86 mol%, more preferably up to 85 mol%. If this sum is too high, the viscosity curve of the melt is shifted to higher temperatures, which is disadvantageous, as already explained above with respect to the component SiO2. If the total amount is too low, too few mixed crystals are formed.

[0056] The total proportion in mol% of the basic components of the LAS glass ceramic, SiO2, Al2O3 and P2O5, is preferably at least 77 Mol%, advantageously at least 81 Mol%, advantageously at least 83 Mol%, more preferably at least 84 Mol% and / or preferably at most 91 Mol%, advantageously at most 89 Mol%, more preferably at most 87 Mol%, according to a variant at most 86 Mol%.

[0057] The ratio of the mol% content of P2O5 to SiO2 is preferably at least 0.005, advantageously at least 0.01, preferably at least 0.012 and / or preferably at most 0.1, more preferably at most 0.08, according to a variant at most 0.07.

[0058] As a further component, the glass ceramic contains lithium oxide (Li2O) in a proportion of at least 7 mol%, advantageously at least 7.5 mol%, preferably at least 8 mol%, particularly preferably at least 8.25 mol%. The proportion of Li2O is limited to a maximum of 9.4 mol%, more preferably a maximum of 9.35 mol%, further preferably a maximum of or less than 9.3 mol%. Li2O is a component of the mixed crystal phase and contributes significantly to the thermal expansion of the glass ceramic. The prescribed upper limit of 9.4 mol% must not be exceeded, otherwise a glass ceramic with a negative coefficient of thermal expansion CTE (0; 50) will result. If the content of Li2O is less than 7 mol%, too few mixed crystals are formed and the CTE of the glass ceramic remains positive.

[0059] Glass ceramics can contain at least one alkaline earth metal oxide selected from the group consisting of CaO, BaO, SrO, wherein the group is collectively referred to as "RO". Components from the RO group are substantially retained in the amorphous glass phase of glass ceramics, and can be very important for maintaining zero expansion of ceramicized materials. If the sum of CaO+BaO+SrO is too high, the target CTE (0; 50) according to the present invention cannot be achieved. The ratio of RO is therefore advantageously up to 6Mol% or up to 5.5Mol%, preferably up to 5Mol%, advantageously up to 4.5Mol%, preferably up to 4Mol%, preferably up to 3.8Mol%, further preferably up to 3.5Mol%, also preferably up to 3.2Mol%. If glass ceramics include RO, a favorable lower limit can be at least 0.1Mol%, advantageously at least 0.2Mol%, preferably at least 0.3Mol%, also preferably at least 0.4Mol%. According to various embodiments, glass ceramics can be free of RO.

[0060] The content of CaO can be preferably up to 5 Mol%, advantageously up to 4 Mol%, advantageously up to 3.5 Mol%, advantageously up to 3 Mol%, more preferably up to 2.8 Mol%, more preferably up to 2.6 Mol%. The glass ceramic can advantageously contain at least 0.1 Mol%, advantageously at least 0.2 Mol%, preferably at least 0.4 Mol%, preferably at least 0.5 Mol% of CaO. The glass ceramic can advantageously contain the component BaO, which is a good glass former, in an amount of at least 0.1 Mol%, preferably at least 0.2 Mol% and / or up to 4 Mol%, advantageously up to 3 Mol%, advantageously up to 2.5 Mol%, preferably up to 2 Mol%, preferably up to 1.5 Mol%, and also preferably up to 1.4 Mol%. The glass ceramic may contain SrO in a content of up to 3 Mol%, advantageously up to 2 Mol%, preferably up to 1.5 Mol%, preferably up to 1.3 Mol%, preferably up to 1.1 Mol%, more preferably up to 1 Mol%, also preferably up to 0.9 Mol% and / or preferably at least 0.1 Mol%. According to various embodiments, the glass ceramic is free of CaO and / or BaO and / or SrO.

[0061] Sodium oxide (Na2O) and / or potassium oxide (KO) and / or cesium oxide (Cs2O) and / or rubidium oxide (Rb2O) may optionally be contained in the glass ceramic, i.e. variants without Na2O and / or without KO and / or without Cs2O and / or without Rb2O are possible. The content of Na2O may advantageously be up to 3 mol%, preferably up to 2 mol%, preferably up to 1.7 mol%, preferably up to 1.5 mol%, preferably up to 1.3 mol%, preferably up to 1.1 mol%. The content of KO may advantageously be up to 3 mol%, preferably up to 2.5 mol%, preferably up to 2 mol%, preferably up to 1.8 mol%, preferably up to 1.7 mol%. The content of Cs2O may advantageously be up to 2 mol%, preferably up to 1.5 mol%, preferably up to 1 mol%, preferably up to 0.6 mol%. The content of Rb2O can advantageously be up to 2 Mol%, preferably up to 1.5 Mol%, preferably up to 1 Mol%, preferably up to 0.6 Mol%. According to a specific embodiment, the glass ceramic contains no Na2O and / or K2O and / or Cs2O and / or Rb2O.

[0062] Na2O, K2O, Cs2O, Rb2O can be included in the glass ceramic in a ratio of at least 0.1Mol%, preferably at least 0.2Mol%, more preferably at least 0.5Mol% respectively and independently of each other. Components Na2O, K2O, Cs2O, Rb2O are substantially retained in the amorphous glass phase of the glass ceramic and can be very important for maintaining the zero expansion of the ceramicized material.

[0063] Therefore, the sum R2O of the contents of Na2O, K2O, Cs2O, and Rb2O can advantageously be at least 0.1 Mol%, preferably at least 0.2 Mol%, advantageously at least 0.3 Mol%, preferably at least 0.4 Mol%. A low R2O content advantageously at least 0.2 Mol% can contribute to increasing the temperature range in which the glass-ceramic expansion curve is flat. The sum R2O of the contents of Na2O, K2O, Cs2O, and Rb2O can advantageously be up to 6 Mol%, preferably up to 5 Mol%, preferably up to 4 Mol%, preferably up to 3 Mol%, preferably up to 2.5 Mol%. If the sum of Na2O+K2O+Cs2O+Rb2O is too low or too high, the target CTE (0; 50) according to the present invention may not be achieved. According to a specific embodiment, the glass-ceramic may be free of R2O.

[0064] The glass ceramic may contain a maximum of 0.35 mol% of magnesium oxide (MgO). Further advantageous upper limits may be a maximum of 0.3 mol%, a maximum of 0.25 mol%, a maximum of 0.2 mol%, a maximum of 0.15 mol%, a maximum of 0.1 mol% or a maximum of 0.05 mol%. The glass ceramic according to the invention is particularly preferably free of MgO. As described above, the MgO component in the glass ceramic causes thermal hysteresis in a temperature range of 0°C to 50°C. The less MgO the glass ceramic contains, the smaller the hysteresis in a specified temperature range.

[0065] The glass ceramic may contain a maximum of 0.5 Mol% zinc oxide (ZnO). Another advantageous upper limit may be a maximum of 0.45 Mol%, a maximum of 0.4 Mol%, a maximum of 0.35 Mol%, a maximum of 0.3 Mol%, a maximum of 0.25 Mol%, a maximum of 0.2 Mol%, a maximum of 0.15 Mol%, a maximum of 0.1 Mol% or a maximum of 0.05 Mol%. The glass ceramic according to the present invention is particularly preferably free of ZnO. As described above as the inventor's discovery, the ZnO component in the glass ceramic causes thermal hysteresis in a temperature range of 0°C to 50°C. The less ZnO the glass ceramic contains, the smaller the hysteresis in the specified temperature range.

[0066] It is important for the hysteresis-free property of the glass ceramic according to the invention that the condition of less than 0.6 mol% of MgO+ZnO is met. Another advantageous upper limit of the sum of MgO+ZnO can be a maximum of 0.55 mol%, a maximum of or less than 0.5 mol%, a maximum of 0.45 mol%, a maximum of 0.4 mol%, a maximum of 0.35 mol%, a maximum of 0.3 mol%, a maximum of 0.25 mol%, a maximum of 0.2 mol%, a maximum of 0.15 mol%, a maximum of 0.1 mol% or a maximum of 0.05 mol%.

[0067] Glass ceramics also include at least one crystal nucleating agent selected from the group consisting of TiO2, ZrO2, Ta2O5, Nb2O5, SnO2, MoO3, WO3. Nucleating agent can be a combination of two or more of the above components. Another advantageous nucleating agent can be HfO2. Therefore, in an advantageous embodiment, glass ceramics include HfO2 and at least one crystal nucleating agent selected from the group consisting of TiO2, ZrO2, Ta2O5, Nb2O5, SnO2, MoO3, WO3. The sum of the proportions of nucleating agents is preferably at least 1.5Mol%, preferably at least 2Mol% or greater than 2Mol%, more preferably at least 2.5Mol%, at least 3Mol% according to some variants. The upper limit can be up to 6Mol%, preferably up to 5Mol%, preferably up to 4.5Mol% or up to 4Mol%. In particularly advantageous variants, the upper and lower limits mentioned are applicable to the sum of TiO2 and ZrO2.

[0068] The glass ceramic may preferably contain titanium dioxide (TiO2) in an amount of at least 0.1 mol%, advantageously at least 0.5 mol%, preferably at least 1.0 mol%, preferably at least 1.5 mol%, preferably at least 1.8 mol% and / or preferably up to 5 mol%, advantageously up to 4 mol%, more preferably up to 3 mol%, further preferably up to 2.5 mol%, preferably 2.3 mol%. TiO2-free variants of the glass ceramic according to the invention are possible.

[0069] The glass ceramic may also advantageously contain zirconium oxide (ZrO2) in an amount of up to 3 mol%, preferably up to 2.5 mol%, more preferably up to 2 mol%, preferably up to 1.5 mol% or up to 1.2 mol%. Preferably, ZrO2 may be contained in an amount of at least 0.1 mol%, more preferably at least 0.5 mol%, at least 0.8 mol% or at least 1.0 mol%. ZrO2-free variants of the glass ceramic according to the invention are possible.

[0070] According to some advantageous variants of the invention, 0 to 5 mol% of Ta2O5 and / or Nb2O5 and / or SnO2 and / or MoO3 and / or WO3 can be contained in the glass ceramic individually or in total and used, for example, as alternative or additional nucleating agents or for adjusting optical properties, such as the refractive index. HfO2 can also be an alternative or additional nucleating agent. In order to adjust the optical properties, Gd2O3, Y2O3, HfO2, Bi2O3 and / or GeO2 can be contained in some advantageous variants, for example.

[0071] The glass ceramic may further comprise one or more conventional fining agents selected from As2O3, Sb2O3, SnO2, SO4 2- 、F -、Cl-、Br - Or a mixture thereof, its content is greater than 0.05Mol% or at least 0.1Mol% and / or up to 1Mol%. However, the fining agent fluorine will reduce the transparency of the glass ceramic, so when this component is present, it is best limited to at most 0.5Mol%, preferably at most 0.3Mol%, preferably at most 0.1Mol%. Preferably, the glass ceramic does not contain fluorine.

[0072] The above glass composition may be added with colored oxides such as Nd2O3, Fe2O3, CoO, NiO, V2O5, MnO2, CuO, CeO2, CR2O3, and rare earth oxides, either individually or in total, in an amount of 0-3 mol%. The preferred variant does not contain colored oxides.

[0073] B2O3 has a negative effect on the transparency of the glass ceramic. Therefore, in an advantageous variant, the content of this component is limited to <0.2 mol%, preferably to a maximum of 0.1 mol%. Preferred variants contain no B2O3.

[0074] According to an advantageous embodiment of the invention, the composition does not contain components not mentioned above.

[0075] According to a favorable embodiment of the present invention, the glass ceramic or green glass according to the present invention is preferably composed of at least 90 Mol%, more preferably at least 95 Mol%, most preferably at least 99 Mol% of the above-mentioned components or preferably consists of the components SiO2, Al2O3, Li2O, P2O5, R2O, RO and a nucleating agent.

[0076] According to an advantageous development of the glass ceramic, it is substantially free of one or more components selected from the group consisting of MgO, ZnO, PbO, B2O3, Cr3, F, and Cd compounds.

[0077] According to the invention, the expression "free of X" or "free of component X" means that the glass ceramic is essentially free of component X, i.e. this component is present in the glass at most as an impurity, but is not added to the composition as a separate component. With regard to impurities, in particular impurities with MgO and / or ZnO, in the variant free of MgO and / or free of ZnO, a limit of 0.03 mol%, preferably 0.01 mol%, based on the respective individual component should not be exceeded. In the case of other glass components, higher impurity contents of up to 0.1 mol%, preferably up to 0.05 mol%, advantageously up to 0.01 mol%, advantageously up to 0.005 mol%, advantageously up to 0.003 mol% for some components, are possible for each component. X here represents any component, for example PbO.

[0078] The glass ceramic of the present invention has high quartz mixed crystals as the main crystalline phase. The main crystalline phase is the crystalline phase with the largest Vol% ratio in the crystalline phase. High quartz mixed crystals are a metastable phase that changes its composition and / or structure or transforms into different crystalline phases depending on the crystallization conditions. Mixed crystals containing high quartz have very low thermal expansion that even decreases with increasing temperature. In an advantageous embodiment, the crystalline phase does not contain β-spodumene and keatite.

[0079] Advantageous embodiments of LAS glass ceramics have a crystalline phase proportion of less than 70% by volume and / or advantageously greater than 45% by volume. The crystalline phase consists of high quartz mixed crystals, which are also referred to as β-eucryptite mixed crystals. The average crystallite size of the high quartz mixed crystals is advantageously <100nm, preferably <80nm, preferably <70nm. The small crystallite size means that the glass ceramic is transparent and can also be polished better. In a specific advantageous variant, the average crystallite size of the high quartz mixed crystals is ≤60nm, preferably ≤50nm. The crystalline phases, their proportions and average crystallite size are determined in a known manner by means of X-ray diffraction analysis.

[0080] According to one embodiment of the present invention, a transparent glass ceramic is produced. Due to the transparency, many characteristics of this glass ceramic can be better evaluated, of course, especially its internal quality. The glass ceramics according to the present invention are transparent, that is, they have an internal transmittance of at least 70% in the wavelength range of 350 to 650nm. B2O3 and / or higher contents of fluorine reduce transparency. Therefore, advantageous variations do not contain one or both of the components mentioned. In addition, the glass ceramics produced within the scope of the present invention are free of pores and cracks. Within the scope of the present invention, "non-porous" means that the porosity is less than 1%, preferably less than 0.5%, and more preferably less than 0.1%. Cracks are gaps in otherwise continuous structures, i.e. discontinuities.

[0081] In order to be able to produce homogeneous glass ceramics in large-scale production facilities, it is advantageous if the green glass on which the glass ceramic is based (and therefore the glass ceramic) has a processing temperature Va of advantageously at most 1330° C., preferably at most 1320° C. Some advantageous variants may have a processing temperature of at most 1310° C. or at most 1300° C. or below 1300° C. The processing temperature Va is the temperature at which the melt viscosity is 10 4 dPas. In particular, homogeneity refers to the homogeneity of the CTE of the glass ceramic over large volumes as well as small numbers, preferably free of inclusions such as bubbles and particles. This is a quality feature of glass ceramics and a prerequisite for use in precision components, especially very large precision components.

[0082] The processing temperature is determined by the composition of the glass ceramic. In particular, since the glass lattice forming component SiO2 is considered to be the decisive component for increasing the viscosity and thus the processing temperature, the maximum SiO2 content is selected according to the above provisions. CTE

[0083] The glass ceramics according to the invention are zero-expansion (see Table 1), i.e. they have a maximum thermal expansion of 0±0.1×10 -6 / K average thermal expansion coefficient CTE. Some advantageous variants even have a CTE of 0±0.05×10 -6 For some applications, it may be advantageous if the average CTE is at most 0±0.1×10-10°C over a larger temperature range, for example in the range of -30°C to +70°C, preferably in the range of -40°C to +80°C. -6 / K, that is, there is zero expansion.

[0084] In order to determine the CTE-T curves of the glass ceramics and precision parts according to the present invention and the comparative examples, the differential CTE (T) is first determined. The differential CTE (T) is determined as a function of temperature. The CTE is then specified according to the following formula (1):

[0085] In order to create a Δl / l0-T curve or expansion curve or a graph of the length change Δl / l0 versus temperature of a test piece (glass ceramic or precision component), the length change of the test piece from an initial length l0 at an initial temperature t0 to a length lt at temperature t can be measured as a function of temperature. In this case, a small temperature interval of, for example, 5°C or 3°C or 1°C is preferably selected to determine the measuring points. For example, such measurements can be performed by expansion measurements, interferometry, such as the Fabry-Perot method, i.e. evaluating the shift of the resonance peak of the laser beam coupled into the material, or other suitable methods. Within the scope of the present invention, an expansion measurement method with a temperature interval of 1°C is selected for a rod-shaped sample of a test piece with a length of 100 mm and a diameter of 6 mm to determine the CTE. The accuracy of the method selected for determining the CTE is preferably at least ±0.05 ppm / K, preferably at least ±0.03 ppm / K. Of course, the CTE may also be determined using a method with an accuracy of at least ±0.01 ppm / K, preferably at least ±0.005 ppm / K, or according to some embodiments even at least ±0.003 ppm / K or at least ±0.001 ppm / K.

[0086] The average CTE for a specific temperature interval, such as the temperature range from 0°C to 50°C, is calculated from the Δl / l0-T curve.

[0087] The CTE-T curve is obtained by deriving the Δl / l0-T curve. From the CTE-T curve, the zero crossing point and the slope of the CTE-T curve within a temperature range can be determined. The form and position of the favorable CTE platform formed in some variants are determined based on the CTE-T curve (see below and Fig.21 and 21 ).

[0088] Advantageous embodiments of precision components comprising glass ceramics according to the invention (especially in the form of substrates) have a high CTE homogeneity. Here, the value of the CTE homogeneity (English: "total spatial variation of CTE") is understood as the so-called peak-to-valley value, i.e. the difference between the respectively highest and respectively lowest CTE values ​​of the samples taken from the precision component. Therefore, the CTE homogeneity does not refer to the CTE of the material of the component, but to the spatial variation of the CTE on the considered detail or the entire precision component. In order to determine the CTE homogeneity, a large number of samples are taken from different positions of the precision component and the CTE values ​​are determined for each of them in ppb / K, where 1 ppb / K=0.001×10 -6 / K. The CTE uniformity, i.e. the spatial variation of CTE, is advantageously at most 5 ppb / K, preferably at most 4 ppb / K, most preferably at most 3 ppb / K over the entire precision component. Methods for determining CTE uniformity and measures for achieving CTE uniformity are described in WO2015 / 124710 A, the disclosure of which is fully incorporated into the present application. Thermal hysteresis

[0089] In the context of the present invention, the glass ceramic has a thermal hysteresis of <0.1 ppm at least in the temperature range from 10° C. to 35° C. and is therefore hysteresis-free (see Fig.10 and 11 ). Thus, at any temperature within the temperature interval from 10°C to 35°C, the glass-ceramic exhibits an isothermal length change of less than 0.1 ppm at a subsequent constant temperature after it has been subjected to a temperature change.

[0090] In an advantageous embodiment, this lack of hysteresis exists at least in a temperature range of 5 to 35°C, preferably at least in a temperature range of 5 to 45°C, preferably at least in a temperature range of >0°C to 45°C, preferably at least in a temperature range of -5°C to 50°C. The temperature range without hysteresis is particularly preferably wider, so that the material or component is also suitable for applications at temperatures up to at least 100°C and advantageously higher. The temperature range without hysteresis is particularly preferably wider. Preferred application temperatures are in the range of -60 to 100°C, more preferably -40°C to +80°C. A special variant of the invention relates to glass ceramics and precision components for application temperatures TA, for example in the range of 5°C to 20°C or TA of 22°C, 40°C, 60°C, 80°C and 100°C, preferably also without hysteresis at these temperatures.

[0091] Thermal hysteresis for glass ceramics and precision parts according to the invention and for comparative examples on precision dilatometers that can determine CTE with a reproducibility of ±0.001 ppm / K and ±0.003 ppm / K absolute values ​​is determined by a temperature interval of 1°C on a sample of a rod-shaped test piece with a length of 100 mm and a diameter of 6 mm (i.e., a precision part sample or a glass ceramic sample) according to the method and device structure disclosed in DE 10 2015113 548 A (the disclosure of which is fully incorporated into the present application). For each sample, the length change Δl / l0 as a function of temperature is measured between cooling at 50°C and a cooling rate of 36K / h to -10°C. After isothermal holding at -10°C for 5 hours, the sample is heated to 50°C at a heating rate of 36K / h and the length change Δl / l0 as a function of temperature is recorded. The thermal hysteresis behavior of the test piece is observed at -5°C, 0°C, 5°C, 10°C, 22°C, 35°C, and 40°C. These points represent the temperature range of -10°C to 50°C, since the hysteresis in this temperature interval decreases with increasing temperature. Thus, a sample that has no hysteresis at 22°C or 35°C will also show no hysteresis in the range up to 50°C.

[0092] To determine the thermal hysteresis at 10°C, individual measured values ​​of the length change at five temperatures of 8°C, 9°C, 10°C, 11°C and 12°C are recorded, i.e. two temperature points above and below 10°C respectively, when heating and cooling the sample at a rate of 36 K / h in the range of -10°C to 50°C. The average value is formed from the difference in the measured values ​​of the heating and cooling curves at these five measuring points and is reported in the table as "Hysteresis @ 10°C" in [ppm].

[0093] To determine the thermal hysteresis at 35°C, the corresponding individual measured values ​​of the length change at five temperatures of 33°C, 34°C, 35°C, 36°C and 37°C are recorded, i.e. two temperature points above and below 35°C, respectively, when heating and cooling the sample at a rate of 36 K / h in the range of -10°C to 50°C. From the differences in the measured values ​​of the heating and cooling curves at these five measuring points, an average value is formed and recorded in the table as "Hysteresis @ 35°C" in [ppm].

[0094] The same procedure was followed for the other temperature points mentioned above.

[0095] Figures 2 to 11 The glass ceramic according to the present invention ( Fig.10 and 11 ) and known glass ceramics ( Figures 2 to 9 ). For better comparability, the range of 6 ppm on the y-axis is always selected for the graphs in the figures.

[0096] Figures 2 to 8 The thermal hysteresis curves of known materials for precision components are shown. The cooling curve (dashed line) and the heating curve (dots) are each clearly spaced apart from one another, especially at lower temperatures, i.e. they run distinctly apart. At 10°C, the spacing exceeds 0.1 ppm, and according to the comparative example, the difference is up to about 1 ppm. This means that the materials and precision components made from them show considerable thermal hysteresis in the relevant temperature range of at least 10° to 35°C.

[0097] The LAS glass ceramics studied, such as Figures 2 to 5 As shown in (Comparative Examples 7, 9 and 10 in Table 2), all contain MgO and ZnO and have thermal hysteresis over a wide temperature range of 10°C to 35°C. Figure 6 and 7 The hysteresis curves of LAS glass ceramics without MgO but with ZnO (Comparative Examples 8 and 14 in Table 2) are shown. Both materials show a strongly increased thermal hysteresis below 15°C. Figure 8 The hysteresis curve of LAS glass ceramic containing no ZnO but MgO (Comparative Example 15 in Table 2) is shown. This material also shows a strongly increased thermal hysteresis below 15°C. Fig. 9 As can be seen from the graph, this known material (Comparative Example 1 in Table 2) has no thermal hysteresis, but the steep curve progression shows that it is not a zero expansion material. The average CTE here is -0.24 ppm / K.

[0098] The LAS glass ceramics and precision components according to the invention have a very low MgO and / or ZnO content or are preferably free of MgO and ZnO. Fig.10 and 11It can be seen that the heating curve and the cooling curve overlap at least in the temperature range of 10° C. to 35° C., i.e. the glass ceramic has no hysteresis. However, the material has no hysteresis not only in the range of 10° C. to 35° C., but also at least in the range of 5 to 35° C. or 5 to 45° C., preferably at least in the range of >0° C. to 45° C. Fig.11 Example 7 in FIG. 1 also has no hysteresis at least in the temperature range of -5°C to 50°C. Other expansion properties

[0099] Advantageous embodiments of the present invention have further advantageous expansion characteristics:

[0100] The TCL value is usually used to describe the expansion behavior of a test piece (glass ceramic or precision component), where TCL stands for "total change in length". Within the scope of the present invention, TCL values ​​are specified for the temperature range of 0°C and 50°C. It is determined from the standardized Δl / l0-T curve of the corresponding test piece (also the Δl / l0-T curve in the figure), where "standardized" means that the length change is 0 ppm at 0°C. The Δl / l0-T curve for the TCL determination is constructed using the same method as described above in conjunction with the CTE determination within the scope of the present invention.

[0101] The TCL value is the distance between the maximum and minimum dl / l0 values ​​within the temperature range: TCL(0;50℃)=|dl / l0 max|+|dl / l0 min| (2) Where "dl" is the change in length at the corresponding temperature, and "l0" is the length of the test piece at 0°C. When calculating, use the dl / l0 values ​​respectively.

[0102] Figures 14 to 17 Expansion curves of known materials are shown, wherein the dl / l0 maximum and dl / l0 minimum values ​​can be read out for calculating the TCL value (see also below). The expansion curves show the curve profile in the temperature range of 0°C to 50°C.

[0103] However, within the scope of the present invention, the flat course of the expansion curve in the temperature range of 0° C. to 50° C. is an advantageous feature of glass ceramics and precision components (see Fig.12 and 13 ). For some advantageous variants, depending on the field of application of the component, a flat profile of the expansion curve is also desirable for other temperature ranges, in particular in the ranges of (20; 40), (20; 70) and / or (-10; 30).

[0104] As an indication of the extent to which the trend of the thermal expansion curve deviates from a simple linear trend, the parameter F is introduced as a measure of the flatness of the expansion curve of an advantageous embodiment of the invention, whereby the CTE curve can be classified: F = TCL(0; 50℃) / |Expansion(0; 50℃)| (3)

[0105] The parameter F is calculated by forming the quotient of the TCL (0; 50) value (in ppm) (see above) and the expansion difference (in ppm) between the temperature points 0°C and 50°C. Since the expansion curve determined by TCL is standardized according to regulations so that the length change at 0°C is 0 ppm, the "expansion difference between the temperature points 0°C and 50°C" corresponds to the "expansion at 50°C", as shown in the table. The expansion at 50°C is used to calculate the parameter F.

[0106] It is advantageous here if the parameter F of the respective material or component is <1.2, preferably <1.1, preferably at most 1.05. The closer the parameter F is to 1, the flatter the expansion curve runs.

[0107] exist Fig.12 , 13 As can be seen from Figures 1 and 18, advantageous embodiments of LAS glass ceramics have a flat profile of the expansion curve not only in the temperature range of 0°C to 50°C but also preferably in a wider temperature range of -30°C to 70°C (here F=1). In contrast, Figures 14 to 17 and 19 show that the known materials exhibit a significantly steeper and more curved course of the expansion curve in the considered temperature range.

[0108] Fig.12 The expansion curve of the favorable glass ceramic of favorable ceramicization based on component example 6 is shown as an example. The section of 1.6ppm on the y-axis is selected for display. The highest expansion value (dl / l0max) is at +50°C (dl / l0 is +0.57ppm, i.e. |0.57ppm|), and the lowest expansion value (dl / l0min) is 0ppm. The expansion difference between the temperature points of 0°C and 50°C corresponds to the amount of "expansion at 50°C", which is 0.57ppm. Thus, the parameter F of the material is calculated as follows: F (Example 6 in Table 1) = 0.57ppm / 0.57ppm = 1.

[0109] Fig.13 An advantageous example of Ringer's (composition according to example 7 of table 1) is shown, in which the parameter F is also 1.

[0110] Advantageous glass ceramics and precision components according to the invention therefore have, for example, a very flat expansion curve in the temperature range from 0° C. to 50° C., i.e. they not only have zero expansion in the temperature range under consideration, but also have small fluctuations in the variation of the linear expansion and thus small fluctuations in the differential CTE in this region. Fig.18 As can be seen in FIG. 1 , advantageous examples of the invention have a flat profile of their expansion curves over an even wider temperature range (here exemplarily from −30° C. to +70° C.). Fig.19 The significantly steeper expansion curves of the known materials can be seen in Figure 1 for the same temperature range. The expansion behavior can also be considered in other selected temperature ranges, in particular (-10; 30), (20; 40), (20, 70), as described below.

[0111] Compared to the advantageous embodiments of glass ceramics and precision components, Figures 14 to 17 The expansion behavior of known materials and precision components made of them is shown, from which the parameter F can be calculated respectively. Figures 14 to 17 As shown in Figure 19, the expansion behavior of materials or precision parts is measured using the same expansion meter as Fig.12 , 13 The expansion behavior of the advantageous embodiment of the glass ceramic shown in Figure 18 is determined under conditions comparable to those of Figure 18. In general, the known materials show a curved course of the expansion curve:

[0112] Fig.14 A commercially available titanium-doped quartz glass is shown. It can be seen that the sum of the expansion values ​​here at +50°C (dl / l0max is +0.73 ppm, i.e. |0.73 ppm|) and the expansion value at 14°C (dl / l0min is -0.19 ppm, i.e. |0.19 ppm|) results in a TCL(0;50) value of approximately 0.92 ppm. The expansion difference between the temperature points of 0°C and 50°C corresponds to the amount of "expansion at 50°C", which is 0.73 ppm. From this, the parameter F of the material is calculated as follows: F(titanium-doped SiO2)=0.92 ppm / 0.73 ppm=1.26.

[0113] Thus, LAS glass ceramics or corresponding precision parts (see Fig.15 ) is calculated as follows: F (known LAS glass ceramics) = 1.19 ppm / 0.11 ppm = 10.82.

[0114] Therefore, cordierite glass ceramics or corresponding precision parts (see Fig.16 ) is calculated as follows: F(known cordierite glass-ceramics)=2.25ppm / 0.25ppm=9.

[0115] Therefore, it is known to sinter cordierite ceramics or corresponding precision parts (see Fig.17 ) is calculated as follows: F (known sintered cordierite ceramic) = 4.2ppm / 2.71ppm = 1.55.

[0116] Glass ceramics with a flat course of expansion curves are very advantageous, because now precision components can not only be optimized for the subsequent application temperature, but also have a similarly low thermal expansion, for example, under higher and / or lower temperature loads, for example during the manufacturing process. Precision components for microlithography, EUV microlithography (also referred to as "EUV lithography" or "EUVL") and metrology are usually used under standard clean room conditions, in particular at room temperature of 22°C. The CTE can be adapted to this application temperature. However, these components are subject to various process steps, such as metal layer coating, cleaning processes, structuring processes and / or exposure processes, in which there may be temperatures that are higher or in some cases lower than the aforementioned temperatures that are subsequently applied in the clean room. Advantageous glass ceramics and precision components made from them are therefore very advantageous, which have a parameter F of <1.2 and therefore have an optimized zero expansion not only at the application temperature but also, if necessary, at higher and / or lower temperatures during production. If the precision component or glass ceramic is used in EUV lithography, i.e. if the precision component is, for example, an EUVL mirror or an EUVL mask blank or a corresponding substrate, properties such as the absence of hysteresis and the parameter F<1.2 are particularly advantageous, since in EUV lithography, in particular the mirror or mask is heated very inhomogeneously in the point or beam direction by the use of rays of high-energy radiation. For such conditions of use, it is advantageous if the precision component or glass ceramic has a CTE-T curve with a low slope in the temperature range around the application temperature (see below).

[0117] Advantageous glass ceramics and precision components, even better optimized for a subsequent application temperature of 20 or 22° C., are distinguished by having a relative length change (dl / l0) ≤|0.10|ppm, preferably ≤|0.09|ppm, particularly preferably ≤|0.08|ppm, particularly preferably ≤|0.07|ppm in a temperature range of 20° C. to 30° C. and / or a relative length change (dl / l0) ≤|0.17|ppm, preferably ≤|0.15|ppm, particularly preferably ≤|0.13|ppm, particularly preferably ≤|0.11|ppm in a temperature range of 20° C. to 35° C. Alternatively or additionally, such optimized glass ceramics and precision components are distinguished by having a relative length change (dl / l0) ≤|0.30|ppm, preferably ≤|0.25|ppm, particularly preferably ≤|0.20|ppm, particularly preferably ≤|0.15|ppm in a temperature range of 20° C. to 40° C. The characteristics based on the relative length changes in different temperature intervals can be preferably obtained from Figures 12 to 19If we talk about the relative length change (dl / l0), the data naturally refers to the corresponding value.

[0118] Zero-expansion, hysteresis-free materials with such favorable expansion behavior are particularly suitable for use as substrates for EUVL mirrors or EUVL mirrors which are heated to different degrees in the light and shadow regions during operation, for example due to corresponding exposure masks. Due to the above-mentioned smaller relative length changes, EUVL mirrors formed from the favorable glass ceramics have lower local gradients (local gradients or local slopes) in the mirror topography than EUVL mirrors made of known materials. The same applies to EUVL mask blanks or EUVL masks or EUVL photomasks.

[0119] In particular, in the case of glass ceramics which exhibit a very flat expansion curve in the temperature range under consideration, which is close to 0 ppm or fluctuates around 0 ppm, which is generally a favorable expansion behavior, it may be advantageous to introduce a further measure of the flatness of the expansion curve as an alternative or in addition to the parameter F, wherein the expansion curve is not in the temperature range (0; 50), but in another temperature interval (Ti), preferably in the temperature range under consideration (20; 40), (20; 70) and / or (-10; 30). This allows for a better classification of the expansion behavior in relation to the subsequent field of application.

[0120] The alternative parameter fT.i. is expressed in (ppm / K) and is defined as: f T.i. =TCL (T.i.) / Temperature interval width (Ti) (4) where Ti describes the temperature interval considered.

[0121] TCL (T.i.) The value is the distance between the highest dl / l0 value and the lowest dl / l0 value in the respectively considered temperature range (Ti), where for TCL (T.i.) The determined expansion curves are standardized according to regulations so that the length change is 0 ppm at 0° C. This means, for example: TCL (20；40℃) =|dl / l0 max|+|dl / l0 min| (5) Where "dl" is the change in length at the corresponding temperature, and "l0" is the length of the test piece at 0°C. When calculating, use the dl / l0 values ​​respectively.

[0122] Substitution parameter f T.i. According to formula (4), by taking TCL (T.i.)The value [in ppm] (see above) is calculated as the quotient of the temperature interval (Ti) in which the expansion difference is taken into account (in K). The width of the temperature interval between 20° C. and 40° C. taken into account is 20 K. If, on the other hand, the course of the expansion curve is taken into account in the interval Ti=(20; 70) or (-10; 30), the divisor of formula (4) is 50 K or 40 K.

[0123] In an advantageous embodiment, the glass ceramic has the substitution parameter f (20；40) <0.024ppm / K and / or alternative parameter f (20；70) <0.039ppm / K and or alternative parameter f (-10；30) <0.015ppm / K.

[0124] Glass ceramics with a very flat course of the expansion curve are very advantageous, since now the precision component can be optimized not only for the subsequent application temperature, but also, for example, for expected higher and / or lower temperature loads. T.i. Suitable for specifying suitable materials according to the specifications required for a particular component application and providing the corresponding precision components. Special precision components and their applications are described below and are included here.

[0125] According to an advantageous embodiment of the glass ceramic or of a component made therefrom, it may be advantageous to replace the parameter f (20；40) <0.024 ppm / K, preferably <0.020 ppm / K, preferably <0.015 ppm / K. Hysteresis-free, zero-expansion components with such an expansion behavior in the temperature range (20; 40°C) can be used particularly well as precision components for microlithography and EUV microlithography at room temperature. Examples of such advantageous glass ceramics can be found in Fig. 27 Seen in.

[0126] According to an advantageous embodiment of the glass ceramic or of a component made therefrom, it may be advantageous to replace the parameter f (20；70) <0.039ppm / K, preferably <0.035ppm / K, preferably <0.030ppm / K, preferably <0.025ppm / K, preferably <0.020ppm / K. Hysteresis-free, zero-expansion components with such an expansion behavior in the temperature range (20; 70°C) can also be used particularly well as precision components for microlithography and EUV microlithography. It is particularly advantageous that the components have a similarly low thermal expansion even at higher temperature loads, which may occur, for example, during the manufacture of the precision components, but which may also occur locally or over large areas during operation. The temperature loads occurring in EUVL precision components have been described above in more detail in conjunction with parameter F, to which reference is made here to avoid repetition. An example of such an advantageous glass ceramic is Fig.29 Shown in.

[0127] According to an advantageous embodiment of the glass ceramic or of a component made therefrom, it may be advantageous to replace the parameter f (-10；30) <0.015 ppm / K, preferably <0.013 ppm / K, preferably <0.011 ppm / K. Hysteresis-free, zero-expansion components with such an expansion behavior in the temperature range (-10; 30°C) can be used particularly well as precision components, in particular as mirror substrates for applications in which temperatures below room temperature also occur, for example as mirror substrates in astronomy or for Earth observation from space. The corresponding components are described in more detail below. An example of such an advantageous glass ceramic is Fig.28 and 30 Shown in.

[0128] Particularly advantageous embodiments of the glass ceramic or of a component made therefrom have an expansion curve for which at least two selectable parameters f (T.i.) Applicable.

[0129] A particularly advantageous embodiment of the glass ceramic or in particular the component made of glass ceramic has an expansion curve for which the parameter F and the at least one alternative parameter f (T.i.) is applicable.

[0130] Fig. 20 and 21 It is shown that advantageous embodiments of LAS glass ceramics and precision components have a CTE plateau. Glass ceramics with a plateau, ie with an optimized zero expansion over a wide temperature range, offer the same advantages associated with the flat course of the expansion curve and the parameter F already described above.

[0131] Advantageously, the differential CTE has a plateau close to 0 ppm / K, i.e., has a temperature interval T of at least 40 K, preferably at least 50 K. P The differential CTE in is less than 0±0.025ppm / K. The temperature range of the CTE platform is denoted by T P Advantageously, the differential CTE is in a temperature interval T with a width of at least 40K. P The concentration can be less than 0±0.015ppm / K.

[0132] Therefore, the CTE platform is understood to be a region extending on a segment of the CTE-T curve, wherein the value of the differential CTE does not exceed 0±0.025 ppm / K, preferably 0±0.015 ppm / K, more preferably 0±0.010 ppm / K, more preferably 0±0.005 ppm / K, i.e., the CTE is close to 0 ppb / K.

[0133] Advantageously, the differential CTE may be less than 0±0.015 ppm / K, i.e. 0±15 ppb / K, in a temperature interval TP having a width of at least 40 K. In a preferred embodiment, a CTE plateau of 0±0.01 ppm / K, i.e. 0±10 ppb / K, may be formed over a temperature interval of at least 50 K. Fig.25 The average curve between 7 and 50° C. is shown, ie even a CTE plateau of 0±0.005 ppm / K, ie 0±5 ppb / K, is shown over a width of more than 40K.

[0134] It may be advantageous if the temperature interval T P In the range of -10 to +100°C, preferably 0 to 80°C.

[0135] The position of the CTE plateau of the glass ceramic is preferably adapted to the application temperature T of the precision part. A Preferably, the application temperature T A In the temperature range of -60°C to +100°C, more preferably -40°C to +80°C. A special variant of the invention relates to the use of a temperature T A The CTE platform, i.e. the curve region with a small differential CTE deviation in the temperature interval Tp, can also be in the temperature ranges of [-10; 100], [0; 80], [0; 30°C], [10; 40°C], [20; 50°C], [30; 60°C], [40; 70°C] and / or [50; 80°C].

[0136] According to an advantageous embodiment of the invention, the CTE-T curve of the glass ceramic or precision component has at least one curve section with a low slope, in particular up to 0±2.5 ppb / K, in a temperature interval with a width of at least 30 K, preferably at least 40 K, more preferably at least 50 K. 2 , Advantageously up to 0±2ppb / K 2 , Advantageously up to 0±1.5ppb / K 2 , preferably up to 0±1ppb / K 2 , preferably up to 0±0.8ppb / K 2 Depending on the specific variant, even up to 0 ± 0.5 ppb / K 2 The slope of .

[0137] The temperature range with a smaller slope is preferably adapted to the application temperature T of precision components. A Preferably, the application temperature T A In the temperature range of -60°C to +100°C, more preferably -40°C to +80°C. A special variant of the invention relates to the use of a temperature T AGlass ceramics and precision parts at 0°C, 5°C, 10°C, 22°C, 40°C, 60°C, 80°C and 100°C. The low slope temperature interval can also be in the temperature range of [-10; 100], [0; 80], [0; 30°C], [10; 40°C], [20; 50°C], [30; 60°C], [40; 70°C] and / or [50; 80°C].

[0138] Fig. 22 The slope of the CTE-T curve of an advantageous glass ceramic or precision component based on the composition of Example 6 from Table 1 in the temperature range of 0°C to 45°C is shown. The CTE slope is less than 0±2.5 ppb / K over the entire temperature range. 2 And in the range of at least 30K width, it is even lower than 0±1.5ppb / K 2 .

[0139] exist Fig.23 As can be seen from the table 1, the CTE slope of the advantageous glass ceramics and precision parts according to composition example 7 is lower than 0±1.0 ppb / K in the entire temperature range from 0°C to 40°C with a width of at least 40K. 2 And in the range of at least 30K width, it is even lower than 0±0.5ppb / K 2 .

[0140] exist Fig.23 As can be seen from the table 1, the CTE slope of the advantageous glass ceramics and precision parts according to composition example 17 is less than 0±1.0 ppb / K over the entire temperature range from 0°C to 45°C with a width of at least 45K. 2 And in the range of at least 30K width, it is even lower than 0±0.5ppb / K 2 .

[0141] Glass ceramics and precision components with such expansion properties are particularly suitable for EUV lithography applications (e.g. as mirrors or substrates for mirrors or masks or mask blanks), since in this area the requirements on materials for optical components and precision components are increasing with regard to having very low thermal expansion, a zero crossing of the CTE-T curve close to the application temperature and in particular a low slope of the CTE-T curve. Within the scope of the invention, advantageous embodiments of the glass ceramic or precision component have a very flat CTE curve, wherein the curve shows a zero crossing and a very low CTE slope and, if necessary, a very flat plateau.

[0142] Low slope features may exist with or without the formation of a favorable CTE plateau.

[0143] Fig.24 and 25It shows how the CTE trend can be adapted to different application temperatures by changing the ceramicizing temperature and / or the ceramicizing time. Fig.24 It can be seen from FIG. 1 that by increasing the ceramicizing temperature by 10 K, the zero crossing point of the CTE-T curve can be shifted from, for example, 12° C. to a value of 22° C. As an alternative to increasing the ceramicizing temperature, the ceramicizing time can also be correspondingly extended. Fig.25 It is shown that a very flat trend of the CTE-T curve can be improved by increasing the ceramicizing temperature by 5 or 10 K. As an alternative to increasing the ceramicizing temperature, the ceramicizing time can also be extended accordingly.

[0144] Advantageous glass ceramics and precision parts also have good intrinsic quality. It is preferably per 100 cm 3 A maximum of 5 inclusions, preferably per 100 cm 3 Maximum 3 inclusions, preferably per 100cm 3 Maximum 1 inclusion. Inclusions are understood according to the invention to mean gas bubbles and crystallites with a diameter greater than 0.3 mm.

[0145] According to one embodiment of the invention, a plurality of spherical plates having a diameter or edge length of at most 800 mm and a thickness of at most 100 mm are provided. 3 Precision components each having up to 5, preferably up to 3, more preferably up to 1 inclusion with a diameter greater than 0.03 mm.

[0146] In addition to the number of inclusions, the maximum diameter of the detected inclusions can also serve as a measure of the internal quality. The maximum diameter of a single inclusion in the total volume of a precision component with a diameter of less than 500 mm is preferably up to 0.6 mm, and in volumes critical to the application, such as near the surface, preferably up to 0.4 mm. The maximum diameter of a single inclusion in a glass-ceramic component with a diameter of 500 mm to less than 2 m is preferably up to 3 mm, and in volumes critical to the application, such as near the surface, preferably up to 1 mm.

[0147] The invention also relates to the use of the glass ceramic according to the invention in precision components. For example, the glass ceramic can form a substrate for a precision component.

[0148] Furthermore, the invention relates to the use of the LAS glass ceramic according to the invention in precision components, in particular for use in metrology, spectroscopy, measuring technology, lithography, astronomy or Earth observation from space, for example as a mirror or mirror carrier for a segmented or integral astronomical telescope, or also as a substrate for a lightweight or ultralight mirror, for example for a space-based telescope, or as a high-precision structural component for distance measurement, for example in space-based optics or for Earth observation, as a precision component, for example a standard for precise measuring technology, a precision measuring rod, a reference plate in an interferometer, as a mechanical precision component, for example for a ring laser gyroscope, a helical spring for watchmaking, for example as a mirror and prism in LCD lithography, and for example as a mask holder, a wafer stage, a reference plate, a reference frame and a grid plate in microlithography and EUV (extreme ultraviolet) microlithography, and furthermore as a mirror or a mirror substrate and / or a photomask substrate or a photomask blank or a photomask mask blank in EUV microlithography.

[0149] Using the glass ceramics according to the invention, precision components of different sizes can be produced:

[0150] One embodiment relates to precision components with relatively small dimensions, in particular with an edge length (width and / or depth) of at least 100 mm and / or at most 1500 mm in an angular (rectangular) shape or with a diameter of at least 100 mm and / or at most 1500 mm in a rounded surface and / or a thickness of less than 50 mm, preferably less than 10 mm and / or at least 1 mm, more preferably at least 2 mm. Such precision components can be used, for example, for microlithography and EUV lithography.

[0151] Another embodiment relates to precision components with very small dimensions, in particular with an edge length (width and / or depth) or a diameter and / or thickness of a few mm (e.g. up to 20 mm or up to 10 mm or up to 5 mm or up to 2 mm or up to 1 mm) to a few tenths of a mm (e.g. up to 0.7 mm or up to 0.5 mm). These precision components can be, for example, spacers in interferometers or components of ultra-stable clocks for quantum technology.

[0152] However, it is also possible to manufacture very large precision parts. One embodiment of the invention therefore relates to parts with a large volume. For this purpose, in the sense of the present application it is understood to be a part having a mass of at least 300 kg, preferably at least 400 kg, preferably at least 500 kg, preferably at least 1 t, more preferably at least 2 t, at least 5 t according to a variant of the invention, or a part having an edge length (width and / or depth) of at least 0.5 m, more preferably at least 1 m and a thickness (height) of at least 50 mm, preferably at least 100 mm in an angular (rectangular) shape, or a part having a diameter of at least 0.5 m, more preferably at least 1 m, more preferably at least 1.5 m and / or a thickness (height) of at least 50 mm, preferably at least 100 mm in a circular shape. In a specific embodiment of the invention, the parts may also be larger, for example having a diameter of at least 3 m or at least 4 m or more. According to a variant, the invention also relates to a rectangular part, wherein preferably at least one surface has a mass of at least 1 m 2 , preferably at least 1.2m 2 , more preferably at least 1.4 m 2 Typically, large volume components are manufactured whose base area is much larger than their height. However, they can also be large volume components with an approximately cubic or spherical shape.

[0153] The precision component can be, for example, an optical component and be a so-called normal incidence mirror, i.e. a mirror which operates at nearly normal incidence, or a so-called grazing incidence mirror, i.e. a mirror which operates at grazing incidence. In addition to the substrate, such a mirror also comprises a coating which reflects the incident radiation. In particular in the case of mirrors for X-rays, the reflective coating is, for example, a multilayer system or a multilayer with a plurality of layers having a high reflectivity in the non-grazing incidence X-ray range. The multilayer system of such a normal incidence mirror preferably comprises 40 to 200 layer pairs, which consist of alternating layers, for example one of the material pairs Mo / Si, Mo / Bi, Ru / Si and / or MoRu / Be.

[0154] In particular, the optical element according to the invention can be an X-ray optical element, i.e. an optical element used in combination with X-rays, in particular soft X-rays or EUV rays, in particular a reticle mask or photomask operating in reflection, in particular for EUV microlithography. It can advantageously be a mask blank. Furthermore, the precision component can advantageously be used as a mirror for EUV lithography or as a substrate for a mirror for EUV lithography.

[0155] Furthermore, the precision components according to the invention can be components for astronomical applications, in particular mirrors. Here, these components can be used for astronomical applications on the ground and in space. High-precision structural components for distance measurement, for example in space, are another advantageous field of application.

[0156] The precision component according to the invention may involve a lightweight structure. The component of the invention may also include a lightweight structure. This means that hollow spaces are provided in certain areas of the component to reduce weight. Preferably, the weight of the component processed by lightweight processing is reduced by at least 80%, more preferably by at least 90%, compared to the unprocessed component.

[0157] The subject of the present invention is also a precision component, which comprises the LAS glass ceramic according to the present invention. This has been described in detail above in conjunction with the glass ceramic and its use in precision components. The entire disclosure is contained in the description of the precision component.

[0158] It goes without saying that the features of the invention mentioned above and still to be explained below can be used not only in the respectively specified combination but also in other combinations, without departing from the scope of the present invention. Example

[0159] Tables 1 and 2 show the compositions of examples and comparative examples of the glass ceramics according to the present invention and their properties.

[0160] The compositions mentioned in Table 1 are melted from commercial raw materials, such as oxides, carbonates and nitrates, in a conventional production process. The green glasses produced according to Table 1 were first ceramized at the respectively specified maximum temperature for the specified duration.

[0161] For example, WO 2015 / 124710 A1 describes the production of glass ceramics for precision components, in particular large precision components.

[0162] Table 1 shows 23 examples (Bsp.) of the present invention, which have no hysteresis and zero expansion at least in the temperature range of 10°C to 35°C. Examples 6, 18, 19 and 20 only show thermal hysteresis starting from about 0°C, and examples 11, 17 and 23 only start from 5°C. Examples 7, 12, 14, 15 and 22 have no hysteresis in the entire temperature range of -5°C to 45°C. In addition, the parameter F<1.2, that is, the course of the expansion curve in the temperature range from 0°C to 50°C is advantageously flat in all examples. In addition, the examples have a processing temperature of ≤1330°C, so that glass ceramics can be manufactured with high uniformity in large-scale production facilities. The processing temperatures specified in Tables 1 and 2 are derived according to DIN ISO 7884-1 (2014, source: Schott Techn. Glass-Katalog).

[0163] In Example 5, after 2.5 days of ceramicization at a maximum temperature of 780°C, the average CTE in further temperature intervals was determined, and the results were as follows: CTE (20; 300°C): -0.17 ppm / K, CTE (20; 500°C): -0.02 ppm / K, CTE (20; 700°C): 0.17 ppm / K.

[0164] For Example 7, the average CTE was determined in the temperature range of 19° C. to 25° C., and the result was that the CTE (19; 25) of Example 7 was −1.7 ppb / K.

[0165] Table 2 shows the comparative examples (Vgl.Bsp). Comparative Examples 1, 2, 5, and 6 have neither MgO nor ZnO, but have an average CTE (0; 50) greater than 0 ± 0.1 × 10 -6 / K, ie these comparative examples are not zero expansion. Furthermore, comparative examples 1 and 2 have a processing temperature of >1330° C. These materials are very viscous, so that it is not possible to produce parts with a high degree of homogeneity in large-scale production facilities.

[0166] Comparative Examples 7 to 16 all contain MgO and / or ZnO, and most of them are zero expansion. However, these comparative examples show thermal hysteresis significantly greater than 0.1 ppm at least in the temperature range from 10°C to 35°C. At room temperature, i.e., 22°C, this group of comparative examples exhibits thermal hysteresis, with the exception of Comparative Examples 14 and 16. Comparative Example 9 also has an unfavorably steep expansion curve in the temperature range of 0°C to 50°C, although it is zero expansion, which can be seen from the high value of parameter F.

[0167] In the tables below, if there is a blank field in the composition information, it means that the component(s) are not intentionally added or not included.

[0168] Table 3 shows the calculation alternative parameters f for different temperature intervals of some advantageous examples and comparative examples of the present invention. (T.i.) , which indicates that the expansion curves of the examples have flatter curves than those of the comparative examples in the specified temperature range.

[0169] It is clear to the person skilled in the art that, depending on the application temperature of the glass ceramic or the precision component comprising the glass ceramic, a glass ceramic having the desired properties, in particular with regard to thermal hysteresis and / or average CTE, is selected. Table 1: Composition, ceramicization and properties (Mol%) Example number (example) 1 2 3 4 5 6 <![CDATA[Li2O]]> 8.5 8.6 8.65 8.75 9.0 8.7 <![CDATA[Na2O]]> 0.6 0.5 0.5 0.4 0.2 <![CDATA[K2O]]> 1.65 1.6 1.65 1.45 0.75 0.6 MgO ZnO CaO 0.45 0.7 1.2 1.6 2.1 2.35 BaO 0.4 0.4 0.75 SrO <![CDATA[Al2O3]]> 16.1 15.2 16.65 17.55 15.85 16.4 <![CDATA[SiO2]]> 68.1 67.95 66.5 65.1 65.5 65.2 <![CDATA[P2O5]]> 1.35 2.25 1.65 1.6 3.05 2.5 <![CDATA[TiO2]]> 2.05 2.0 2.0 1.95 2.1 2.05 <![CDATA[ZrO2]]> 0.95 0.95 0.95 0.95 1.05 1.0 <![CDATA[As2O3]]> 0.25 0.25 0.25 0.25 0.2 0.25 sum 100.0 100.0 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> 110.60 110.95 109.75 108.85 110.50 108.70 MgO+ZnO <![CDATA[ΣR2O(R=Na.K.Cs.Rb)]]> 2.25 2.1 2.15 1.85 0.75 0.8 ΣRO(R=Ca.Ba.Sr) 0.45 0.7 1.2 2.0 2.5 3.10 Va[℃] 1312 1318 1292 1271 1275 Ceramic temperature[℃] 760 780 780 760 780 770 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 2.5 Crystalline phase [Vol. %] 53 54 53 49 64 57 Crystal size [nm] 39 40 45 42 40 40 Average CTE (0; +50℃) [ppm / K] 0.05 0.07 0.10 0.10 -0.03 0.01 TCL(0;+50℃) 2.47 3.41 5.22 5.1 1.64 0.57 |Expansion at 50°C| 2.47 3.41 5.22 5.1 1.64 0.57 Parameter F 1.00 1.00 1.00 1.00 1.00 1.00 Hysteresis@45℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@22℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@10℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@+5℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@0℃[ppm] 0.1 Hysteresis@-5℃[ppm] 0.16 Ceramic temperature[℃] 760 780 780 760 800 780 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 2.5 Average CTE (-30; +70℃) [ppm / K] 0.03 0.06 0.09 0.08 0.02 0.01 Average CTE (-40; +80℃) [ppm / K] 0.02 0.05 0.08 0.08 0.004 0.006 Table 1 (continued): Composition, ceramization and properties (Mol%) Example number (example) 7 8 9 10 11 12 <![CDATA[Li2O]]> 9.15 9.0 8.9 9.25 8.35 9.3 <![CDATA[Na2O]]> 0.6 0.45 0.1 1.1 0.8 <![CDATA[K2O]]> 0.9 0.5 0.65 0.2 MgO ZnO CaO 0.95 2.5 2.5 1.8 1.1 BaO 0.55 0.6 0.85 14 SrO 0.6 0.8 <![CDATA[Al2O3]]> 17.95 17.3 17.2 18.35 17.4 17.9 <![CDATA[SiO2]]> 64.0 63.05 64.55 62.55 66.35 64.1 <![CDATA[P2O5]]> 2.6 3.85 2.9 3.35 0.8 2.85 <![CDATA[TiO2]]> 2.05 2.05 2.1 2.05 2.0 2.15 <![CDATA[ZrO2]]> 1.0 1.05 1.05 1.05 1.0 1.05 <![CDATA[As2O3]]> 025 0.25 0.25 0.25 025 0.25 sum 100.0 100.0 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> 109.75 108.05 109.05 108.80 108.10 110.60 MgO+ZnO <![CDATA[∑R2O(R=Na,K,Cs,Rb)]]> 1.50 0.95 0.75 1.1 1.0 ∑RO(R=Ca,Ba,Sr) 1.5 2.5 3.1 2.4 2.75 14 Va[℃] 1267 1256 1258 1248 Ceramic temperature[℃] 810 800 800 810 780 820 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 2.5 Crystalline phase [Vol. %] 58 62 64 64 52 60 Crystal size [nm] 48 47 45 46 47 47 Average CTE (0; +50℃) [ppm / K] 0.007 0.06 -0.08 -0.08 -0.03 -0.08 TCL(0;+50℃) 0.37 3 3.88 3.89 1.34 3.96 |Expansion at 50°C| 0.37 2.88 3.78 3.89 1.34 3.96 Parameter F 1.00 1.04 1.03 1.00 1.00 1.00 Hysteresis@45℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@22℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@10℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@+5℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@0℃[ppm] <0.1 <0.1 <0.1 Hysteresis@-5℃[ppm] <0.1 0.15 <0.1 Ceramic temperature[℃] 820 780 800 810 780 820 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 2.5 Average CTE (-30; +70℃) [ppm / K] 0.03 0.006 -0.08 -0.07 -0.05 -0.10 Average CTE (-40; +80℃) [ppm / K] 0.02 -0.01 -0.10 -0.08 -0.05 -0.1 Table 1 (continued): Composition, ceramization and properties (Mol%) Example number (example) 13 14 15 16 17 18 <![CDATA[Li2O]]> 9.1 9.35 8.9 8.6 9.05 8.7 <![CDATA[Na2O]]> 0.1 0.45 0.45 0.65 0.6 0.9 <![CDATA[K2O]]> 0.6 1.1 0.95 1.65 0.85 0.3 MgO 0.25 ZnO 0.15 0.45 CaO 1.3 1.1 1.25 0.85 0.65 BaO 1.1 0.4 1.05 0.45 1.15 SrO <![CDATA[Al2O3]]> 17.9 18.85 16.95 16.35 18.0 18.1 <![CDATA[SiO2]]> 62.0 61.6 67.15 67.9 63.75 64.0 <![CDATA[P2O5]]> 4.6 3.95 1.6 2.75 2.45 <![CDATA[TiO2]]> 2.1 2.0 2.05 2.05 2.05 2.1 <![CDATA[ZrO2]]> 1.05 1.0 1.05 1.0 1.05 1.0 <![CDATA[As2O3]]> 0.15 0.2 0.2 0.2 0.2 0.2 sum 100.0 100.0 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> 107.50 108.35 111.65 110.90 109.00 107.50 MgO+ZnO 0.40 0.45 <![CDATA[ΣR2O(R=Na,K,Cs,Rb)]]> 0.70 1.55 1.4 2.3 1.45 1.2 ΣRO(R=Ca,Ba,Sr) 2.40 1.50 2.3 1.3 1.8 Va[℃] Ceramic temperature[℃] 790 815 815 770 830 815 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 2.5 Crystalline phase [Vol. %] 62 61 53 52 59 59 Crystal size [nm] 46 50 46 39 48 48 Average CTE (0; +50℃) [ppm / K] 0.08 -0.01 0.08 0.04 0.01 -0.015 TCL(0;+50℃) 4.00 0.58 4.14 2.07 0.61 0.74 |Expansion at 50°C| 4.00 0.54 4.14 2.07 0.61 0.74 Parameter F 1.00 1.07 1.00 1.00 1.00 1.00 Hysteresis@45℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@22℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@10℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@+5℃[ppm] 0.11 <0.1 <0.1 <0.1 <0.1 Hysteresis@0℃[ppm] 0.19 <0.1 <0.1 <0.1 0.11 Hysteresis@-5℃[ppm] 0.22 <0.1 <0.1 0.13 0.18 Ceramic temperature[℃] 790 815 770 820 815 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 Average CTE (-30; +70℃) [ppm / K] 0.12 -0.02 0.02 -0.06 -0.03 Average CTE (-40; +80℃) [ppm / K] 0.11 -0.04 0.01 -0.07 -0.04 Table 1 (continued): Composition, ceramization and properties (Mol%) Example number (example) 19 20 21 22 23 <![CDATA[Li2O]]> 9.15 8.1 9.35 9.15 8.85 <![CDATA[Na2O]]> 0.55 0.4 0.7 0.45 0.55 <![CDATA[K2O]]> 0.85 1.0 0.25 0.6 0.85 MgO 0.30 ZnO 0.20 CaO 0.8 2.25 1.25 0.8 1.0 BaO 0.45 1.1 0.8 0.70 SrO <![CDATA[Al2O3]]> 17.75 15.45 16.85 16.85 14.45 <![CDATA[SiO2]]> 64.0 68.05 64.45 67.35 67.95 <![CDATA[P2O5]]> 2.75 1.55 3.35 2.50 <![CDATA[TiO2]]> 2.0 1.95 3.80 1.95 <![CDATA[ZrO2]]> 1.0 1.0 2.5 1.0 <![CDATA[As2O3]]> 0.2 0.25 0.2 0.2 0.2 sum 100.0 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> 109.75 108.55 111.20 113.10 112.20 MgO+ZnO 0.5 <![CDATA[ΣR2O(R=Na,K,Cs,Rb)]]> 1.4 1.4 0.95 1.4 ΣRO(R=Ca,Ba,Sr) 1.25 2.25 2.35 1.7 Va[℃] Ceramic temperature[℃] 815 770 810 825 800 Ceramicization duration [days] 2.5 2.5 2.5 2.5 2.5 Crystalline phase [Vol. %] 61 51 62 63 59 Crystal size [nm] 50 33 76 33 42 Average CTE (0; +50℃) [ppm / K] -0.075 0.07 -0.075 -0.03 0.035 TCL(0;+50℃) 3.73 3.38 3.75 1.7 1.77 |Expansion at 50°C| 3.73 3.38 3.75 1.7 1.77 Parameter F 1.00 1.00 1.00 1.00 1.00 Hysteresis@45℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@22℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@10℃[ppm] <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@+5℃[ppm] <0.1 <0.1 0.12 <0.1 <0.1 Hysteresis@0℃[ppm] 0.14 0.1 0.17 <0.1 <0.1 Hysteresis@-5℃[ppm] 0.21 0.17 0.21 <0.1 0.11 Ceramic temperature[℃] 815 770 810 825 Ceramicization duration [days] 2.5 2.5 2.5 2.5 Average CTE (-30; +70℃) [ppm / K] -0.09 0.05 -0.09 -0.05 Average CTE (-40; +80℃) [ppm / K] -0.10 0.04 -0.10 -0.06 Table 2: Composition, ceramicization and properties (Mol%) Comparative Example No. (Comparative Example) 1 2 5 6 <![CDATA[Li2O]]> 8.1 9.15 9.45 9.5 <![CDATA[Na2O]]> 0.4 0.4 0.2 0.1 <![CDATA[K2O]]> 0.15 0.2 0.7 0.55 MgO ZnO CaO 4.15 2.2 0.4 BaO 0.6 1.75 SrO <![CDATA[Al2O3]]> 12.45 14.2 16.75 16.6 <![CDATA[SiO2]]> 72.3 71.7 64.15 65.55 <![CDATA[P2O5]]> 0.62 3.3 2.2 <![CDATA[TiO2]]> 1.3 1.75 2.05 2.1 <![CDATA[ZrO2]]> 1.0 1.2 1.0 1.05 <![CDATA[As2O3]]> 0.15 0.15 0.2 0.2 sum 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> MgO+ZnO <![CDATA[ΣR2O(R=Na.K.Cs.Rb)]]> 0.55 0.6 0.9 0.65 ΣRO(R=Ca.Ba.Sr) 4.15 0.6 2.2 2.15 Va[℃] 1345 1340 Ceramic temperature[℃] 760 800 800 Ceramicization duration [days] 10 2.5 2.5 Crystalline phase [Vol. %] 60 66 58 Crystal size [nm] 63 45 47 Average CTE (0; +50℃) [ppm / K] -0.25 -0.27 -0.46 TCL(0;+50℃) |Expansion at 50°C| Parameter F Hysteresis@45℃[ppm] Hysteresis@35℃[ppm] Hysteresis@30℃[ppm] Hysteresis@22℃[ppm] <0.1 Hysteresis@10℃[ppm] <0.1 Hysteresis@+5℃[ppm] <0.1 Hysteresis@0℃[ppm] 0.13 Hysteresis@-5℃[ppm] 0.24 Ceramic temperature[℃] Ceramicization duration [days] Average CTE (-30; +70℃) [ppm / K] Average CTE (-40; +80℃) [ppm / K] Table 2 (continued): Composition, ceramization and properties (Mol%) Comparative Example No. (Comparative Example) 7 8 9 10 11 12 <![CDATA[Li2O]]> 8.5 7.78 9.32 9.2 9.4 9.0 <![CDATA[Na2O]]> 0.1 0.8 0.1 0.2 0.1 <![CDATA[K2O]]> 0.5 MgO 1.8 1.2 1.6 1.2 1.6 ZnO 1.3 1.8 0.4 0.6 0.6 0.4 CaO 2.42 1.0 1.2 1.0 1.3 BaO 1.07 0.36 0.4 0.3 0.5 SrO <![CDATA[Al2O3]]> 16.9 15.39 19.11 16.2 19.0 16.4 <![CDATA[SiO2]]> 64.3 65.42 61.4 63.3 61.4 63.9 <![CDATA[P2O5]]> 3.4 2.47 3.97 3.8 3.9 3.5 <![CDATA[TiO2]]> 1.9 1.67 1.92 2.2 1.9 2.1 <![CDATA[ZrO2]]> 1.1 0.92 1.07 1.1 1.1 1.2 <![CDATA[As2O3]]> 0.2 0.26 0.25 0.2 0.2 0.1 sum 100.0 100.0 100.0 100.0 100.0 100.1 <![CDATA[SiO2+(5xLi2O)]]> MgO+ZnO 3.1 1.8 1.6 2.2 1.8 2.0 <![CDATA[ΣR2O(R=Na,K,Cs,Rb)]]> 0.6 0.8 0.1 0.2 0.1 ΣRO(R=Ca,Ba,Sr) 3.49 1.36 1.6 1.3 1.8 Va[℃] Ceramic temperature[℃] 810 760 810 760 Ceramicization duration [days] 10 10 5 10 Crystalline phase [Vol. %] 76 Crystal size [nm] 72 Average CTE (0; +50℃) [ppm / K] 0.03 0.02 0.002 -0.15 0.03 -0.05 TCL(0;+50℃) 1.19 3.68 1.32 0.35 |Expansion at 50°C| 0.11 3.68 1.28 0.35 Parameter F 10.82 1.00 1.03 1.00 Hysteresis@45℃[ppm] 0.11 <0.1 <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] 0.14 <0.1 0.12 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] 0.18 <0.1 0.16 <0.1 0.1 0.11 Hysteresis@22℃[ppm] 0.27 0.14 0.24 0.14 0.16 0.17 Hysteresis@10℃[ppm] 0.61 0.42 0.54 0.38 0.85 0.43 Hysteresis@+5℃[ppm] 0.85 0.61 0.74 0.56 0.61 0.61 Hysteresis@0℃[ppm] 1.1 0.81 0.92 0.76 0.85 0.82 Hysteresis@-5℃[ppm] 1.2 0.96 1.16 0.93 1.04 0.97 Ceramic temperature[℃] Ceramicization duration [days] Average CTE (-30; +70℃) [ppm / K] Average CTE (-40; +80℃) [ppm / K] Table 2 (continued): Composition, ceramization and properties (Mol%) Comparative Example No. (Comparative Example) 13 14 15 16 <![CDATA[Li2O]]> 8.4 8.2 9.4 9.3 <![CDATA[Na2O]]> 0.05 0.35 0.1 0.25 <![CDATA[K2O]]> 0.6 0.25 MgO 1.8 ZnO 0.95 1.2 0.60 CaO 2.3 2.35 1.0 BaO 0.85 SrO <![CDATA[Al2O3]]> 16.55 16.5 17 18.95 <![CDATA[SiO2]]> 65.15 64.8 64.4 61.5 <![CDATA[P2O5]]> 3.4 3.3 3.5 4.05 <![CDATA[TiO2]]> 2.0 2.0 1.95 2.05 <![CDATA[ZRO2]]> 1.1 1.1 1.05 1.05 <![CDATA[As2O3]]> 0.15 0.2 0.2 0.15 sum 100.0 100.0 100.0 100.0 <![CDATA[SiO2+(5xLi2O)]]> MgO+ZnO 0.95 1.2 1.8 0.60 <![CDATA[ΣR2O(R=Na,K,Cs,Rb)]]> 0.05 0.35 0.7 0.50 ΣRO(R=Ca,Ba,Sr) 2.25 2.35 1.85 Va[℃] Ceramic temperature[℃] 770 810 790 830 Ceramicization duration [days] 5 1 5 2.5 Crystalline phase [Vol. %] 73 69 74 66 Crystal size [nm] 43 47 56 41 Average CTE (0; +50℃) [ppm / K] -0.03 -0.08 -0.06 0.07 TCL(0;+50℃) 4.29 |Expansion at 50°C| 3.55 Parameter F 1.21 Hysteresis@45℃[ppm] <0.1 <0.1 <0.1 <0.1 Hysteresis@35℃[ppm] <0.1 <0.1 <0.1 <0.1 Hysteresis@30℃[ppm] <0.1 <0.1 <0.1 <0.1 Hysteresis@22℃[ppm] 0.13 <0.1 0.16 <0.1 Hysteresis@10℃[ppm] 0.44 0.3 0.44 0.15 Hysteresis@+5℃[ppm] 0.67 0.55 0.63 0.23 Hysteresis@0℃[ppm] 0.97 0.84 0.85 0.35 Hysteresis@-5℃[ppm] 1.3 1.13 1.0 0.5 Ceramic temperature[℃] Ceramicization duration [days] Average CTE (-30; +70℃) [ppm / K] Average CTE (-40; +80℃) [ppm / K] Table 3: Alternative parameter f T.i .Examples and comparative examples for selection <![CDATA[f T.i. [ppm / K]]]> <![CDATA[Titanium-doped SiO2]]> Example 6 Example 7 Example 12 Example 14 Example 17 Example 18 20-40℃ 0.024 0.010 0.009 0.014 0.012 0.016 20-70℃ 0.039 0.011 0.010 0.023 0.038 0.014 0.022 -10-30℃ 0.015 0.004 0.011 0.006

Claims

1. A LAS glass ceramic having a maximum value of 0±0.1×10 -6 / K and a thermal hysteresis of <0.1 ppm at least in the temperature range of 10-35 °C, and comprises the following components (in Mol % based on oxides): SiO2 60–71 Li2O 7–9.4 MgO+ZnO 0–<0.6 At least one component selected from the group consisting of P2O5, R2O, RO, wherein R2O may be Na2O and / or K2O and / or Cs2O and / or Rb2O, and RO may be CaO and / or BaO and / or SrO, A nucleating agent in an amount of 1.5 to 6 mol%, wherein: The nucleating agent is at least one component selected from the group consisting of TiO2, ZrO2, Ta2O5, Nb2O5, SnO2, MoO3, and WO3.

2. LAS glass ceramics according to claim 1, wherein, It contains Al2O3 in an amount of 10 to 22 Mol%, preferably 11 to 21 Mol%, and / or P2O5 in an amount of 0.1 to 6 Mol%, preferably 0.3 to 5 Mol%.

3. LAS glass ceramics according to claim 1 or 2, wherein, The total content of ZnO+MgO is ≤0.55 Mol%, advantageously ≤0.5 Mol%, advantageously <0.5 Mol%, advantageously 0.45 Mol%, advantageously ≤0.4 Mol%, preferably ≤0.3 Mol%, preferably ≤0.2 Mol% and / or the content of MgO is ≤0.35 Mol%, preferably ≤0.3 Mol%, preferably ≤0.25 Mol%, preferably ≤0.2 Mol%, more preferably ≤0.1 Mol% and / or the content of ZnO is ≤0.5 Mol%, preferably ≤0.45 Mol%, preferably ≤0.4 Mol%≤0.3 Mol%, preferably ≤0.2 Mol%, more preferably ≤0.1 Mol%.

4. The LAS glass-ceramic according to any one of the preceding claims, wherein: The content of SiO2 is ≤70 Mol%, preferably ≤69 Mol%, particularly preferably ≤68.5 Mol%.

5. The LAS glass-ceramic according to any one of the preceding claims, wherein: The total content of RO (CaO+BaO+SrO) is ≥0.1 Mol%, preferably ≥0.2 Mol%, advantageously ≥0.3 Mol%, preferably ≥0.4 Mol% and / or ≤6 Mol%, preferably ≤5 Mol%, advantageously ≤4.5 Mol%, advantageously ≤4.0 Mol%, preferably ≤3.8 Mol%, preferably ≤3.5 Mol%, preferably ≤3.2 Mol%.

6. The LAS glass-ceramic according to any one of the preceding claims, wherein: The total content of RO2 (Na2O+K2O+Cs2O+Rb2O) is ≥0.1Mol%, preferably ≥0.2Mol%, advantageously ≥0.3Mol%, preferably ≥0.4Mol% and / or ≤6Mol%, advantageously ≤5Mol%, preferably ≤4Mol%, preferably ≤3Mol%, preferably ≤2.5Mol%.

7. The LAS glass-ceramic according to any one of the preceding claims, wherein the total content of the nucleating agent is ≥1.5 Mol%, preferably ≥2.5 Mol%, advantageously ≥3 Mol% and / or ≤6 Mol%, advantageously ≤5 Mol%, preferably ≤4.5 Mol%, preferably ≤4 Mol%.

8. The LAS glass-ceramic according to any one of the preceding claims, wherein: The conditions are suitable for: molar content SiO2+(5×molar content Li2O)≥106, preferably molar content SiO2+(5×molar content Li2O)≥107.5, and / or The conditions are suitable for: the molar content SiO2+(5×molar content Li2O)≤115.5, preferably the molar content SiO2+(5×molar content Li2O)≤114.

5.

9. The LAS glass-ceramic according to any one of the preceding claims, wherein: The processing temperature Va is at most 1330°C, preferably at most 1320°C.

10. The LAS glass-ceramic according to any one of the preceding claims, wherein: The main crystalline phase is high quartz mixed crystals and advantageously the average crystallite size of the high quartz mixed crystals is <100 nm, advantageously <80 nm, preferably <70 nm and / or the crystalline phase proportion is less than 70 vol%.

11. The LAS glass-ceramic according to any one of the preceding claims, wherein: Parameter F <1.2, preferably <1.1, preferably at most 1.05, where F = TCL (0; 50° C.) / | expansion (0; 50° C.) |.

12. The LAS glass-ceramic according to any one of the preceding claims, wherein: Substitution parameter f (20；40) <0.024ppm / K and / or alternative parameter f (20；70) <0.039ppm / K and / or alternative parameter f (-10；30) <0.015ppm / K.

13. The LAS glass-ceramic according to any one of the preceding claims, wherein: It has a relative length change (dl / l0) of ≤|0.10|ppm, preferably ≤|0.09|ppm, particularly preferably ≤|0.08|ppm, particularly preferably ≤|0.07|ppm in the temperature range of 20°C to 30°C and / or a relative length change (dl / l0) of ≤|0.17|ppm, preferably ≤|0.15|ppm, particularly preferably ≤|0.13|ppm, particularly preferably ≤|0.11|ppm in the temperature range of 20°C to 35°C.

14. The LAS glass-ceramic according to any one of the preceding claims, wherein: It has a relative length change (dl / l0) of ≤|0.30| ppm, preferably ≤|0.25| ppm, particularly preferably ≤|0.20| ppm, particularly preferably ≤|0.15| ppm in the temperature range from 20°C to 40°C.

15. The LAS glass-ceramic according to any one of the preceding claims, wherein: The CTE-T curve has a value of ≤0±2.5ppb / K in a temperature interval with a width of at least 30K. 2 , preferably ≤0±2ppb / K 2 , preferably ≤0±1.5ppb / K 2 , particularly preferably ≤0±1ppb / K 2 The slope of .

16. The LAS glass-ceramic according to any one of the preceding claims, wherein: It has a thermal hysteresis of <0.1 ppm at least in the temperature range of 5 to 45°C, advantageously at least in the temperature range of >0 to 45°C, preferably at least in the temperature range of -5 to 50°C.

17. Precision component comprising a LAS glass-ceramic according to any one of the preceding claims.

18. The precision component according to claim 17 is used in particular in metrology, spectroscopy, measuring technology, lithography, astronomy or Earth observation from space, for example as a mirror or mirror carrier for a segmented or integral astronomical telescope, or also as a reduced-weight or ultra-light mirror substrate, for example for a space-based telescope, or as a high-precision structural component for distance measurement, for example in space or in optics for Earth observation, as a precision component, for example a standard for precise measuring technology, a precision measuring rod, a reference plate in an interferometer, as a mechanical precision component, for example for a ring laser gyroscope, a helical spring for watchmaking, for example as a mirror and prism in LCD lithography, and for example as a mask holder, a wafer stage, a reference plate, a reference frame and a grid plate in microlithography and EUV microlithography, and as a mirror and / or a photomask substrate or a photomask blank in EUV microlithography.

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