Glass ceramics with low phase volume and high NUV / VIS / NIR optical extinction

Abstract

The present invention relates to an electromagnetic radiation absorbing element having a glass ceramic: an ilmenite-type solid solution having crystallites of the formula (FexMnyMgz) TiO3 in the crystalline phase; having a low volume fraction of crystalline phase (also referred to as a low crystalline phase volume); and has a very high optical extinction coefficient (extinction / optical path length) in the near ultraviolet (NUV), visible light (VIS) and near infrared (NIR) spectral range. The glass ceramics may be produced and processed by standard glass processing methods, such as melting, thermoforming, bending, stretching, and / or tempering (thermal tempering and chemical tempering). The invention also relates to a method for producing said glass ceramic and to the use of said glass ceramic.

Description

Technical Field

[0001] This invention relates to a glass-ceramic element capable of efficiently absorbing electromagnetic radiation, particularly in the visible spectrum. The invention also relates to a glass-ceramic having a low crystalline phase volume fraction (also known as low crystalline volume) and a very high optical extinction coefficient (extinction / optical path length) in the visible light (VIS) spectral range and advantageously in the near-ultraviolet (NUV) and near-infrared (NIR) spectral ranges. The electromagnetic radiation absorbing element and / or glass-ceramic can be produced and processed by standard glass processing methods, such as melting, thermoforming, bending, stretching, and / or tempering (thermal tempering and chemical tempering). The invention further relates to a method for producing the glass-ceramic and its uses. Background Technology

[0002] In the context of this invention, electromagnetic radiation absorbing elements include filters, layers, optical elements, substrates, etc. Commonly used electromagnetic radiation absorbing elements typically include glass. Glasses with medium to high optical extinction coefficients in NUV, VIS, and NIR are known. These glasses are also called black glass due to their black optical appearance. Such glasses are used in various applications where reduced light transmittance in the corresponding wavelength range is required. For many applications, glass is an advantageous material in this regard because of its excellent formability. In particular, glass can be formed into various shapes and forms using well-known forming processes.

[0003] However, a known drawback of black glass is that it cannot achieve very high optical extinction coefficients. Reducing light transmittance within the target wavelength may be sufficient for some applications. However, in cases where further reduction in transmittance is required, this can only be achieved by using black glass with increased thickness, which is disadvantageous in many applications due to the associated increased weight and space requirements. Summary of the Invention

[0004] In this context, the object of the present invention is to overcome the shortcomings of the prior art and to provide a material that combines a very high optical extinction coefficient at near-ultraviolet (NUV), visible light (VIS) and near-infrared (NIR) wavelengths with the excellent formability of glass.

[0005] This objective is achieved through the technical subject matter of the claims of this patent.

[0006] In the context of this invention, it has been found that the extinction coefficient of an absorbing material in a crystalline structure is significantly higher than that of its embedded in an amorphous glass structure. Furthermore, if the crystal exhibits a size on the order of UV / VIS wavelengths and beyond, in addition to the extinction coefficient, the scattering process also contributes due to the difference in refractive index between the crystal and the matrix.

[0007] In an advantageous embodiment, the extinction coefficient is greater than 100 / cm over the entire wavelength range of 350 nm to 700 nm.

[0008] On one hand, the present invention relates to an electromagnetic radiation absorbing element comprising a glass-ceramic phase and an amorphous phase. The electromagnetic radiation absorbing element may include or be represented by glass-ceramic itself. In other words, the electromagnetic radiation absorbing element may include or be composed of glass-ceramic. The extinction coefficient of the glass-ceramic is greater than 20 / cm across the entire wavelength range of 350 nm to 700 nm. This means that for each wavelength in this range, the extinction coefficient is at least 20 / cm. The crystalline phase includes ilmenite-type solid solutions. Ilmenite is known to be FeTiO3. Ilmenite-type solid solutions in the context of this invention comprise FeTiO3 and MnTiO3, and optionally MgTiO3; therefore, it represents a mixture composed of these crystals, thus forming a so-called ilmenite-type solid solution.

[0009] The solid solution named ilmenite can also be described as (Fe x Mn y Mg z TiO3 solid solution, wherein x + y + z = 1.00, x is at least 0.2 and y is at least 0.2. Advantageously, x is in the range of 0.2 to 0.8, y is in the range of 0.2 to 0.8, and x + y is in the range of 0.4 to 1.00.

[0010] In the solid solutions mentioned, the Fe and Mn cations exist primarily in their lower oxidation states, i.e., as Fe(II) and / or Mn(II). Therefore, the melting of the glass, as a glass-ceramic precursor, is carried out under reducing conditions, which can be achieved, for example, by adding carbonaceous materials to the melt. However, Fe(II) and / or Mn(II) may certainly exist in the crystalline phase, while some mixtures of Fe(III) and / or Mn(IV), or Fe(II) and Fe(III) and / or Mn(II) and Mn(IV), exist in the amorphous phase. For the sake of consistency, the terms Fe₂O₃ and / or MnO₂ are used below and within the meaning of this disclosure to represent all oxidation states of Fe and / or Mn, respectively. This also applies if this disclosure relates to Fe and / or Mn. It must be noted that Mg always exists in the Mg(II) state, denoted as MgO.

[0011] Preferably, the crystal phase comprises FeTiO3 and MnTiO3, and optionally MgTiO3. This means that, in this embodiment, FeTiO3 and MnTiO3 are present in the crystal phase, which may optionally contain MgTiO3. This means that the crystal phase preferably comprises a solid solution comprising (Fe, Mn)TiO3 or (Fe, Mn, Mg)TiO3. The crystal phase may also comprise FeTiO3 and solid solutions comprising (Mn, Mg)TiO3. However, advantageously, the content of MnO2 may be limited, particularly advantageously, it is limited to less than 5 mol% of the overall composition. This means that a (Fe, Mn)TiO3 solid solution may provide the most advantageous embodiment. The same applies to MgO, with an advantageous upper limit of less than 5 mol%, thereby forming a (Fe, Mn, Mg)TiO3 solid solution.

[0012] It has been found that such electromagnetic radiation absorbing elements containing the aforementioned ilmenite-type solid solutions exhibit excellent absorption characteristics in the visible light range of the spectrum. In the wavelength range of 400 nm to 700 nm, the logarithm of the extinction coefficient E exhibits a predominantly linear slope along the wavelength. This means that, within the wavelength range of 400 nm to 700 nm, the actual extinction coefficient E at a given wavelength λ within this range is... λ The logarithm deviates from the linear slope within this range by at most 20%.

[0013] Calculate the linear function in the wavelength range of 400nm to 700nm using the following formula: Where E 400 The extinction coefficient, E, is the extinction coefficient at a wavelength of 400 nm. 700 The extinction coefficient is the extinction coefficient at a wavelength of 700 nm, and λ is the observed E. λ The target wavelength.

[0014] Based on the above, this means that within the wavelength range of 400nm to 700nm, the extinction coefficient E observed at a given wavelength λ is... λ The following conditions must be met: The term "logE" λ "E" refers to the extinction coefficient E observed at a given wavelength λ. λ The decimal logarithm of E. The conditions established above indicate that logE λ exist to Within the range.

[0015] The near-linear wavelength dependence of the extinction coefficient on a logarithmic scale appears to contribute to achieving low color shift in components and / or glass-ceramic materials.

[0016] The amount of crystalline phase can be adjusted according to the desired performance. Advantageously, it is anticipated that microcrystals of the crystalline phase are embedded in the amorphous phase, and the volume fraction of the crystalline phase is >0.1 vol% and ≤30 vol%, preferably ≤20 vol%, most preferably ≤10 vol%, while maintaining a minimum volume fraction >0.1% in both cases. These volume fractions offer the advantage that the elements and / or glass-ceramic materials can be processed, at least similarly to glass elements and / or glass materials. Unless otherwise stated, volume fractions given in this disclosure as % per unit volume refer to the corresponding volume fraction relative to the total volume of the glass-ceramic material.

[0017] As can be seen from the foregoing description, the amorphous phase refers to a substance with a host matrix similar to that of the crystalline phase. At least in the wavelength range of 350 nm to 700 nm, the specific absorption of the crystalline phase is advantageously higher than that of the amorphous phase. More advantageously, in said wavelength range, the crystalline phase contributes at least 80%, even more advantageously at least 90%, most preferably at least 96%, or about 100% to the total absorption of the glass-ceramic.

[0018] It has been found that the materials described in this article can be tailored to the specific needs of their applications. For example, various crystallite sizes can be obtained.

[0019] For crystallite sizes smaller than the wavelength, it has been found that absorption mainly occurs within the crystal phase, while scattering contributes only a small portion (if it exists).

[0020] Smaller crystallites in the visible light wavelength range can be obtained by cooling the molten material and forming crystallites within the melt at temperatures below approximately 800°C. Larger crystallites can be obtained by cooling the molten material to room temperature or maintaining it at a specific temperature during post-heat treatment. Such post-treatment can be performed at temperatures between approximately 800 and 850°C. These larger crystallites may contribute more to scattering.

[0021] Surprisingly, as mentioned above, the relatively low volume fraction of this crystalline phase can provide the described high absorbance. Therefore, the intrinsic absorption of the microcrystals must be very high.

[0022] It can also be inferred that the microcrystalline nature and very high absorption result in a "neutral black" appearance, which is unattainable by amorphous phases that are predominantly absorption-based. To achieve this effect, the minimum thickness of the element and / or the material needs to be surprisingly low. For example, a thickness of 2 mm or less can achieve a deep black effect. This thickness corresponds to the optical path length where the absorption occurs.

[0023] In an advantageous embodiment, the crystalline phase comprises microcrystals having an average diameter DC in the range of 1 nm to 2000 nm and an average refractive index NC in the range of 1.7 to 6, particularly in the visible light (VIS) spectral range. More advantageously, the DC ranges from 1 nm to 1000 nm, or 2 nm to 500 nm, or 2 nm to 200 nm. The refractive index NC of the microcrystals can advantageously be from 1.8 to 5, particularly in the VIS spectral range.

[0024] The refractive index NC has been calculated using density functional theory. DC is measured by high-resolution scanning transmission electron microscopy (HRSTEM), scanning electron microscopy (SEM), and / or calculated by X-ray diffraction analysis (XRD). These methods are known in the art.

[0025] The amorphous phase has a refractive index NG. In an advantageous embodiment, NG is in the range of 1.45 to 1.65, particularly in the VIS spectral range. The combination of the aforementioned DC and / or NC values ​​with these NG values ​​allows the crystallites to produce scattering effects.

[0026] As described above, the volume fraction of the crystalline phase is preferably at least 0.1% by volume and at most 30% by volume, wherein the volume fraction of the amorphous phase is at least 70% by volume, and wherein the crystalline phase is composed of the chemical formula (Fe). x Mn y Mg z The microcrystalline composition of TiO3 is given by x + y + z = 1.00, where x is in the range of 0.2 ≤ x ≤ 0.8, y is in the range of 0.2 ≤ y ≤ 0.8, and z is in the range of 0.4 ≤ z ≤ 0.6. Advantageously, the following conditions are satisfied: 0.4 ≤ x + y ≤ 1 and / or 0.2 ≤ x + z ≤ 0.8 and / or 0.2 ≤ y + z ≤ 0.8. Of course, the condition x + y + z = 1 must be satisfied.

[0027] Preferably, the glass-ceramic is composed of a crystalline phase and an amorphous phase.

[0028] The glass-ceramic of the present invention combines very high optical extinction coefficients in the near-ultraviolet (NUV), visible (VIS), and near-infrared (NIR) spectral ranges with processability in standard glass processing methods such as thermoforming, bending, stretching, and / or tempering (thermal tempering and chemical tempering)

[0029] Glass-ceramics can be obtained by heat-treating a starting glass comprising a relevant amount of TiO2 and oxides of iron, manganese, and / or magnesium. This process is necessary to form the desired chemical formula (Fe...). x Mn y Mg z The microcrystals of TiO3, importantly, require a starting glass comprising sufficient amounts of Fe2O3 and MnO2. To provide the desired oxide state of iron, the starting glass is prepared under reducing melting conditions so that, after heat treatment, the desired chemical formula (Fe2O3) is formed. x Mn y Mg z TiO3 microcrystals. To avoid ambiguity, the term "heat treatment" as used herein includes every temperature profile over time, including temperature increases, holds, and / or decreases.

[0030] Advantageously, reducing melting conditions lead to Fe 2+ With the total amount of Fe (i.e. Fe) 2+ The ratio of / ∑Fe) is in the range of 0.3 to 0.8. This means, in other words, that the advantageous implementation satisfies the relation 0.3≤Fe 2+ / ∑Fe≤0.8. Preferably, the average size of the crystallites is in the range of 1nm to 2000nm, for example 2 to 1500nm, 5 to 1200nm, 7 to 1000nm, 8 to 750nm, 9 to 500nm, 10 to 320nm, 15nm to 250nm, 20nm to 200nm, 25nm to 150nm, or 30nm to 100nm. The average size of the crystallites is preferably at least 1nm, at least 2nm, at least 5nm, at least 7nm, at least 8nm, at least 9nm, at least 10nm, at least 15nm, at least 20nm, at least 25nm, or at least 30nm. The average size of the microcrystals is preferably at most 2000 nm, 1500 nm, 1200 nm, 1000 nm, 750 nm, 500 nm, 320 nm, 250 nm, 200 nm, 150 nm, or 100 nm. This average size of the microcrystals is particularly advantageous for achieving the very high extinction levels required in the NUV, VIS, and NIR spectral ranges.

[0031] In some embodiments, the average size of the crystallites is preferably in the range of 1 to 20 nm, for example, 2 to 18 nm, 5 to 15 nm, or 8 to 12 nm. The average size of the crystallites may preferably be at least 1 nm, at least 2 nm, at least 5 nm, or at least 8 nm. The average size of the crystallites may preferably be at most 20 nm, at most 18 nm, at most 15 nm, or at most 12 nm.

[0032] In some embodiments, the average size of the crystallites is preferably in the range of 20 to 300 nm, for example, 50 to 275 nm, 100 to 250 nm, or 150 to 225 nm. The average size of the crystallites may preferably be at least 20 nm, at least 50 nm, at least 100 nm, or at least 150 nm. The average size of the crystallites may preferably be at most 300 nm, at most 275 nm, at most 250 nm, or at most 225 nm.

[0033] In some embodiments, the average size of the crystallites is preferably in the range of 300 to 2000 nm, for example, 500 to 1500 nm, 700 to 1300 nm, or 800 to 1200 nm. The average size of the crystallites may preferably be at least 300 nm, at least 500 nm, at least 700 nm, or at least 800 nm. The average size of the crystallites may preferably be at most 2000 nm, at most 1500 nm, at most 1300 nm, or at most 1200 nm.

[0034] In addition to including those with the chemical formula (Fe) x Mn y Mg z In addition to the crystalline phase composed of TiO3 microcrystals, the glass-ceramic may also include one or more additional crystalline phases. The volume of the one or more additional crystalline phases relative to the total volume of the glass-ceramic is advantageously in the range of 0.0 vol% to 80 vol%, more advantageously in the range of 0.0 vol% to 20 vol%. The volume fraction of the one or more additional crystalline phases is advantageously at most 15 vol%. In some embodiments, the volume fraction of the one or more additional crystalline phases may, for example, be at least 5 vol%.

[0035] Particularly preferred is that the glass-ceramic does not contain any additional crystalline phase.

[0036] Relative to the total volume of the glass-ceramic, by the chemical formula (Fe) x Mn y Mg z The volume fraction of the crystalline phase composed of TiO3 microcrystals is preferably in the range of 0.1 vol% to 30 vol%, for example 0.2 to 20 vol% or 15 vol%, 0.5 to 10 vol%, 1.0 to 7.5 vol%, or 2.0 to 5.0 vol%. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) x Mny Mg z The volume fraction of the crystalline phase composed of TiO3 microcrystals is preferably at least 0.1 vol%, more preferably at least 0.2 vol%, more preferably at least 0.5 vol%, more preferably at least 1.0 vol%, and more preferably at least 2.0 vol%. This is particularly advantageous for achieving very high extinction in the NUV, VIS, and NIR spectral ranges. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) x Mn y Mg z The volume fraction of the crystalline phase composed of TiO3 microcrystals is preferably at most 30%, at most 20% by volume, at most 15% by volume, at most 10% by volume, at most 7.5% by volume, or at most 5.0% by volume. x Mn y Mg z The relatively low volume fraction of the crystalline phase composed of microcrystals of TiO3 is particularly advantageous for achieving excellent formability and / or processability of glass ceramics in standard glass processing methods such as thermoforming, bending, stretching and / or tempering (thermal tempering and chemical tempering).

[0037] The glass-ceramic of the present invention comprises an amorphous phase. The volume fraction of the amorphous phase relative to the total volume of the glass-ceramic is preferably at least 70% by volume, more preferably at least 80% by volume or at least 85% by volume, more preferably at least 90% by volume, and even more preferably at least 95% by volume. A high volume fraction of the amorphous phase is beneficial to the formability and / or processability of the glass-ceramic in standard glass processing methods (such as thermoforming, bending, stretching, and / or tempering (thermal tempering and chemical tempering)). The volume fraction of the amorphous phase is preferably at most 99% by volume, at most 98% by volume, at most 97% by volume, or at most 96% by volume. Limiting the volume fraction of the amorphous phase is beneficial to achieving particularly high extinction in the NUV, VIS, and NIR spectral ranges. The volume fraction of the amorphous phase is preferably from 70% by volume to 99% by volume, particularly in the range of 80% by volume or 85% by volume to 98% by volume, 90% by volume to 97% by volume, or 95% by volume to 96% by volume.

[0038] Preferably, the determination is based on XRD (X-ray diffraction) of the chemical formula (Fe). x Mn y Mg z The volume fraction of crystalline and / or amorphous phases in the microcrystal composition of TiO3.

[0039] The refractive index NG of the amorphous phase at wavelengths within the visible light (VIS) spectral range is preferably 1.45 to 1.65.

[0040] At wavelengths within the VIS range (i.e., in the range of 350 nm to 700 nm), the chemical formula (Fe) is used.x Mn y Mg z The refractive index NC of the crystalline phase composed of TiO3 microcrystals is preferably from 1.8 to 5. Or in other words, the refractive index NC is in the range of 1.5 to 5 at each given wavelength in the range of 350 nm to 700 nm.

[0041] The glass-ceramic of the present invention is characterized by having a very high extinction coefficient in the NUV, VIS, and NIR spectral ranges, particularly in the entire wavelength range of 300 nm to 3000 nm, or in the entire wavelength range of 300 nm to 1400 nm, or particularly in the range of 350 nm to 700 nm (commonly referred to as the visible spectrum range). The term "extinction coefficient E" or "optical density per unit length OD" as used herein refers to a measure of the attenuation intensity of the transmittance of the glass-ceramic to light of a specified wavelength λ per unit length d. This measure is expressed in normalized form as the extinction coefficient E, with units of " / cm". Hereinafter, the extinction coefficient is also simply referred to as "extinction". The extinction coefficient and OD are determined based on the following transmittance measurements: Light of wavelength λ is transmitted through the glass-ceramic sample of this invention, the sample thickness of which is “d”. The light intensity I0 of the incident light and the light intensity I1 of the transmitted light are measured. The unit of light intensity is W / m². 2 Transmittance "T" is defined as the ratio I1 / I0, which is the percentage of transmitted light intensity. Transmittance T can also be called "external transmittance" and includes losses due to absorption, scattering, reflection, etc. In contrast, "internal transmittance" only involves losses caused by absorption and scattering within the glass-ceramic.

[0042] In the above formula, "d" represents the sample thickness (i.e., the optical path length), and "T" represents the external transmittance of wavelength λ (i.e., the percentage of transmitted light intensity).

[0043] Preferably, the extinction coefficient E is at least 20 / cm, more preferably at least 50 / cm, more preferably at least 100 / cm, more preferably at least 150 / cm, more preferably at least 200 / cm, more preferably at least 250 / cm, more preferably at least 300 / cm, more preferably at least 350 / cm, more preferably at least 400 / cm, and more preferably at least 500 / cm, across the entire wavelength range of 300nm to 1400nm or 350nm to 700nm. According to the invention, the extinction coefficient can be so high that an upper limit is meaningless. However, values ​​as high as 1000 / cm, 10000 / cm, or even 100000 / cm have been observed or appear feasible within the VIS range.

[0044] As mentioned above, one advantage of components and / or glass-ceramics having the aforementioned crystalline phase is that they can be formed using known glassmaking processes, particularly thermoforming. Surprisingly, it has been found that glass-ceramics having the aforementioned crystalline phase have a softening point up to 50°C higher than the starting glass. This is presumably a consequence of the small volume of the microcrystals.

[0045] Preferably, the glass-ceramic of the present invention can have an advantageous average coefficient of linear thermal expansion (CTE) in the temperature range of 20°C to 300°C. Specifically, the CTE can be in the range of 3.0 to 10.0 ppm / K, 3.3 to 9.7 ppm / K, 3.5 to 9.5 ppm / K, 4.0 to 9.0 ppm / K, more preferably 4.5 to 8.0 ppm / K, and even more preferably 5.0 to 7.0 ppm / K. Preferably, the CTE is at least 3.0 ppm / K, at least 3.3 ppm / K, at least 3.5 ppm / K, at least 4.0 ppm / K, more preferably at least 4.5 ppm / K, and even more preferably at least 5.0 ppm / K. Preferably, the CTE is at most 10.0 ppm / K, at most 9.7 ppm / K, at most 9.5 ppm / K, at most 9.0 ppm / K, more preferably at most 8.0 ppm / K, and even more preferably at most 7.0 ppm / K. The chromatic ester reaction (CTE) of glass-ceramics is primarily determined by the CTE of the amorphous phase. Therefore, the CTE can be customized independently of the extinction coefficient, which is a particular advantage in terms of design freedom. The CTE can be determined according to DIN ISO 7991:1998-02.

[0046] The glass-ceramic of the present invention is not limited to certain compositions. However, certain compositional ranges are particularly advantageous for achieving the desired technical effects.

[0047] Specifically, the possible phase volume is determined by the TiO2 content. Preferably, the glass-ceramic comprises 1 to 10 mol% TiO2.

[0048] Regarding the chemical formula (Fe) x Mn y Mg z The required volume of TiO2 per mole of TiO2 microcrystals necessitates a total of 1 mole of Fe(II) + Mn(II) + Mg(II) to obtain the desired chemical formula (Fe... x Mn y Mg zMicrocrystals of TiO3. An excess of any one or more components will ultimately exist in the amorphous phase and / or one or more additional crystalline phases. Ideally, the major amounts of total TiO2, Fe2O3, MnO2, and optionally MgO are present in the phases of the chemical formula (Fe2O3). x Mn y Mg z TiO2 is present in the crystalline phase composed of microcrystals, and not in the amorphous phase or one or more additional crystalline phases. Therefore, preferably, the molar amount of TiO2 is quite close to the sum of the molar amounts of Fe2O3, MnO2, and optionally MgO. Preferably, the ratio of the molar amount of TiO2 to the sum of the molar amounts of Fe2O3, MnO2, and MgO is in the range of 0.50 to 2.00, more preferably 0.75 to 1.50, more preferably 0.80 to 1.25, more preferably 0.90 to 1.10, more preferably 0.95 to 1.05, more preferably 0.98 to 1.02, and more preferably 0.99 to 1.01. Advantageously, the amount of MgO present is less than 5 mol%, most preferably 0 mol%.

[0049] As previously stated, the use of the terms Fe2O3 and MnO2 is not related to the oxidation state of Fe and Mn, but rather to generalize the oxidation state referred to in microcrystalline solid solutions and / or amorphous phases.

[0050] The sum of the molar amounts of Fe2O3, MnO2 and MgO is preferably in the range of 0.1 to <15 mol%.

[0051] The molar amount of Fe2O3 is preferably in the range of 0.1 to 5 mol%.

[0052] The molar amount of MnO2 is preferably in the range of 0.5 to 5 mol%.

[0053] The molar amount of MgO is preferably in the range of 0 to <5 mol%.

[0054] Preferably, the glass-ceramic comprises the following components in amounts (in mole %): More preferably, the glass ceramic comprises the following components in amounts (in mole %): The term "sum of R2O" refers to the sum of the amounts of alkali metal oxides in glass ceramics, particularly the sum of the amounts of Li2O, Na2O, and K2O.

[0055] The term "RO sum" refers to the sum of the amounts of alkaline earth metal oxides and ZnO in glass ceramics, especially the sum of the amounts of MgO, CaO, SrO, BaO and ZnO.

[0056] The glass-ceramic of the present invention may include one or more colorants, selected from the group consisting of Cr2O3, V2O5, NiO, CoO, and combinations thereof. Advantageously, the total amount of colorant in the glass-ceramic, in molar terms, is in the range of 50 ppm to 500 ppm. Preferably, the total amount of colorant in the glass-ceramic is at least 50 ppm. More preferably, the total amount of colorant in the glass-ceramic is at most 500 ppm.

[0057] Possibly, the glass-ceramic comprises Cr₂O₃ and / or V₂O₅ in amounts ranging from 50 ppm to 500 ppm in molar terms. Most preferably, the glass-ceramic comprises Cr₂O₃ and / or V₂O₅ in an amount of at least 50 ppm. More preferably, the glass-ceramic comprises Cr₂O₃ and / or V₂O₅ in an amount of at most 500 ppm.

[0058] When the glass-ceramic composition is described above using relative amounts of simple oxides “Cr2O3”, “V2O5”, “NiO”, “CoO”, and “TiO2”, this does not imply any limitation on the oxidation state of the corresponding components. For example, “Cr2O3” is not intended to be limited to the amount of chromium (III) in the glass-ceramic. Rather, the term is used to encompass all chromium in all oxidation states present in the glass-ceramic. The same applies to “Cr2O3”, “V2O5”, “NiO”, “CoO”, and “TiO2”.

[0059] This invention also relates to a method for producing glass ceramics, and more particularly to a method for producing the glass ceramics of this invention, the method comprising the following steps: a) Providing a starting glass comprising: 1-20 mol% TiO2, Fe2O3 and MnO2, and optionally MgO, wherein Fe2O3 is present in an amount of at least 0.1 mol% and MnO2 in an amount of at least 0.5 mol%, wherein advantageously, the step of providing the starting glass includes melting the glass feedstock under reducing conditions and cooling the melt to obtain the starting glass; and b) Heat-treating the starting glass to obtain a glass-ceramic, wherein the heat treatment includes steps corresponding to 10 5 Up to 10 11 dPas, especially 10 6 Up to 10 10 dPas, 10 7 Up to 10 10 dPas or 10 8 Up to 10 10 The starting glass is heat-treated at a temperature within the viscosity range of dPas for 1 to 20 hours.

[0060] This invention also relates to a method for producing glass ceramics, and more particularly to a method for producing the glass ceramics of this invention, the method comprising the following steps: a) Providing a starting glass comprising: 1-20 mol% TiO2, Fe2O3 and MnO2, and optionally MgO, wherein the total amount of Fe2O3, MnO2 and MgO is at least 0.6 mol%, wherein advantageously, the step of providing the starting glass includes melting the glass feedstock under reducing conditions and cooling the melt to obtain the starting glass; and b) Heat-treating the starting glass to obtain a glass-ceramic, wherein the heat treatment includes heat-treating the starting glass to form microcrystals at temperature stages, said temperature stages including: at least one stage of 600°C to 700°C, and / or one stage of 700°C to 800°C, and / or one stage of 800°C to 1000°C, advantageously including a combination of at least two said stages.

[0061] The possible phase volume is determined by the sum of TiO2 or Fe2O3 + MnO2 + MgO. Preferably, the starting glass comprises 1 to 20 mol% TiO2. Embodiments may include up to 15 mol% or up to 10 mol% TiO2, respectively. These upper limits can be combined in particular with lower limits of 1 mol% and / or 1.5 mol%.

[0062] The preferred advantageous range of the components is as described above.

[0063] The molar amount of MgO in the starting glass is preferably in the range of 0 to <5 mol%. However, advantageously, the amount of MgO is limited to <4 mol%, and especially at most 3 mol%. An advantageous embodiment does not contain MgO, unless it is present at most as an impurity, in an amount that may be at most 0.3 mol%.

[0064] Advantageously, the starting glass comprises the following components in amounts (in mole %) shown below: More preferably, the starting glass comprises the following components in amounts (in mole %): The term "sum of R2O" refers to the sum of the amounts of alkali metal oxides in the starting glass, particularly the sum of the amounts of Li2O, Na2O, and K2O.

[0065] The term "RO sum" refers to the sum of the amounts of alkaline earth metal oxides and ZnO in the starting glass, particularly the sum of the amounts of MgO, CaO, SrO, BaO, and ZnO.

[0066] The starting glass may include one or more colorants, selected from the group consisting of Cr2O3, V2O5, NiO, CoO, and combinations thereof. Preferably, the total amount of colorant in the starting glass is in the range of 50 ppm to 500 ppm in molar terms. Preferably, the total amount of colorant in the glass-ceramic is at least 50 ppm. Preferably, the total amount of colorant in the starting glass is at most 500 ppm.

[0067] Preferably, the starting glass comprises Cr2O3 and / or V2O5 in a molar amount ranging from 50 ppm to 500 ppm. Preferably, the glass ceramic comprises Cr2O3 and / or V2O5 in a amount of at least 50 ppm. Preferably, the glass ceramic comprises Cr2O3 and / or V2O5 in an amount of at most 500 ppm.

[0068] When the glass-ceramic composition is described above using relative amounts of simple oxides “Cr2O3”, “V2O5”, “NiO”, “CoO”, and “TiO2”, this does not imply any limitation on the oxidation state of the corresponding components. For example, “Cr2O3” is not intended to be limited to the amount of chromium (III) in the glass-ceramic. Rather, the term is used to encompass all chromium in all oxidation states present in the glass-ceramic. The same applies to “Cr2O3”, “V2O5”, “NiO”, “CoO”, and “TiO2”.

[0069] Preferably, reducing melting conditions are used in the production of the starting glass. This is particularly beneficial for forming a chemical formula (Fe) during heat treatment. x Mn y Mg z Microcrystals of TiO3. Preferably, reducing conditions are obtained by adding carbohydrates, particularly sugars, to the glass raw material. Furthermore, to obtain particularly good results, relatively high temperatures can be used during the melting process. Advantageously, temperatures in the range of 1500°C to 1700°C, more preferably in the range of 1550°C to 1650°C, are used during the melting process. The melting temperature is preferably at least 1500°C, more preferably at least 1550°C. The melting temperature is preferably at most 1700°C, more preferably at most 1650°C. When heating the melt using a gas burner, the oxygen-to-gas ratio can be reduced to achieve or maintain reducing conditions. Thus, Fe... 2+ The ratio to the total Fe was set in the range of 0.3 to 0.8.

[0070] The temperature at which microcrystals are formed preferably corresponds to 10 5 Up to 10 11 dPas, especially 10 6 Up to 10 10 dPas, 107 Up to 10 10 dPas or 10 8 Up to 10 10 Viscosities in the dPas range. Such temperatures are particularly advantageous for achieving very high extinction coefficients in the NUV, VIS, and NIR spectral ranges.

[0071] At a specified temperature, it may form, in particular, the chemical formula (Fe). x Mn y Mg z TiO3 microcrystals have an average diameter in the range of 1 to 2000 nm.

[0072] The duration of microcrystal formation is preferably in the range of 1 to 20 hours, more preferably 2 to 15 hours. The specified duration is preferably at least 1 hour, more preferably at least 2 hours. The duration is preferably at most 20 hours, more preferably at most 15 hours.

[0073] The heating rate for heating the initial glass to the desired temperature is preferably in the range of 1 to 15 K / min, more preferably 2 to 10 K / min. The heating rate is preferably at least 1 K / min, more preferably at least 2 K / min. The heating rate is preferably at most 15 K / min, more preferably at most 10 K / min.

[0074] It has been observed that the formation of microcrystals can be advantageously achieved if the ratio of the sum of alkali metal oxides and alkaline earth metal oxides to the sum of boron oxide and aluminum oxide is within a controlled range, most advantageously in the range of 0.4 to 0.8.

[0075] In other words, most advantageously, The range is from 0.4 to 0.6. For calculation purposes, the content of the oxides referred to is used; for example, NaO represents Na as an alkali metal, and CaO represents Ca as an alkaline earth metal.

[0076] This invention also relates to the use of the glass-ceramics described herein, particularly in the fields of fiber optics, optical filters, pigment-free ceramic decoration, or as (ultra)thin glass or cover glass. This invention includes uses in fiber optics, optical filters (e.g., radar), pigment-free ceramic decoration (especially for inkjet printing), and / or colored / tempered (ultra)thin glass.

[0077] The uses also include applications as cover glass for electronic devices, or as cover glass for at least part of the housing of electronic devices, or as part of the housing of household appliances.

[0078] The present invention also relates to colored bulk glass, powder, coating, fiber, tube, rod and / or wafer comprising or composed of the glass ceramics of the present invention. Attached Figure Description

[0079] Figure 1 This is a scanning electron microscope (SEM) image of the glass-ceramic of the present invention, with a magnification of 200,000x. The scale bar represents 100 nm.

[0080] Figure 2 The extinction characteristics of the two glass-ceramic samples of the present invention in the spectral range of 350 to 800 nm are shown as wavelength dependent on the extinction, with the y-axis showing extinction on a logarithmic scale and the x-axis showing wavelength.

[0081] Figure 3 This is a differential scanning calorimetry (DSC) curve, with the x-axis representing temperature and the y-axis representing the DSC signal (in mW / mg). The temperature curve on which this curve is based is an ascending temperature curve, which corresponds to a descending viscosity. The exothermic reaction in the sample is presented as a positive peak.

[0082] Figure 4 Extinction is shown over a wide spectral range. Detailed Implementation

[0083] Example 1. Starting glass The starting glass is produced under reducing melting conditions at a melting temperature of 1700°C, comprising TiO2, Fe2O3, and other components as shown in the table below. The table lists the components in mol% (%). 2. Heat treatment steps The resulting starting glass was heat-treated at 730°C for 10 hours (heat treatment step).

[0084] 3. Glass and ceramics The obtained glass-ceramic has an amorphous phase and is composed of the chemical formula (Fe). x Mn y Mg z The crystalline phase consists of microcrystals of TiO3. The amorphous phase has a volume fraction of 97.5% and is composed of the chemical formula (Fe). x Mn y Mg z The volume fraction of the crystalline phase composed of TiO3 microcrystals was 2.5% by volume. The volume fraction was determined by XRD (X-ray diffraction).

[0085] like Figure 1As shown, crystallite sizes ranging from 5 to 200 nm have been observed using small-angle X-ray scattering (SAXS) analysis and scanning electron microscopy (SEM). The average crystallite size is 37 nm.

[0086] Very thin samples with thicknesses of 60µm and 70µm were produced by slicing and polishing.

[0087] like Figure 2 As shown, when measured using Examples 1 and 2 in the table above, this glass-ceramic exhibits very high extinction. Figure 2 In the diagram, extinction relative to wavelength is plotted. Measurement points marked E1 represent Example 1, and measurement points marked E2 represent Example 2. It can be seen that these examples exhibit very high extinction. The extinction on this logarithmic scale is very uniform across the visible spectrum and satisfies the linear approximation described above.

[0088] Figure 4 The figure illustrates the wavelength dependence of extinction over a wider spectral range. Example 1, denoted as E1, and Example 2, denoted as E2, are combined in this figure. It can be seen that the glass-ceramic provides high absorption over a broad spectral range. This enables applications requiring absorption over a very wide wavelength range.

[0089] 4. Temperature dependence of crystallite formation To investigate the temperature dependence of crystallite formation, differential scanning calorimetry (DSC) experiments were performed. The initial glass sample was subjected to a temperature program in which the temperature was increased from 380°C to 1000°C at a rate of 5.0 K / min. The sample weight was 35.9 mg. The sample was placed in a crucible. An empty crucible of the same type was used as a control. Both the sample crucible and the control crucible were placed in an insulated furnace. The temperatures of both chambers were then controlled to ensure that the temperatures on both sides remained identical. The electrical power required to reach and maintain this state was then recorded. Figure 3 The DSC signal shown is the ratio of this electrical power to the sample weight. This DSC experiment was performed in an argon atmosphere.

[0090] In such Figure 3 In the DSC experiment shown, the positive peak (exothermic reaction) indicates crystallization. Figure 3 The experimental results shown indicate that there is a two-step crystallization process, based on the moderate intensity signal at 610°C and the stronger signal at 760°C.

[0091] In another DSC experiment, the first peak appeared at 650°C, indicating that at 10 10 Small ilmenite (FeTiO3) type microcrystals formed at dPas viscosity. At 730°C, at 10... 8 At a viscosity of dPas, a chemical formula (Fe) is formed.x Mn y Mg z Larger microcrystals of TiO3. When the temperature exceeds 1000°C and the viscosity is 10... 5 At dPas, all microcrystals dissolve in the melt.

[0092] The invention can be summarized by the following observations. These observations should not limit the scope of the invention and can be combined in any way.

[0093] 1. An electromagnetic radiation absorbing element comprising a glass-ceramic phase and an amorphous phase, wherein the extinction coefficient of the glass-ceramic is greater than 20 / cm over the entire wavelength range of 350 nm to 700 nm, preferably greater than 100 / cm over the entire wavelength range of 350 nm to 700 nm, wherein the crystalline phase comprises a phase having the chemical formula (Fe... x Mn y Mg z A microcrystalline ilmenite-type solid solution of TiO3, wherein x+y+z = 1.00.

[0094] 2. The electromagnetic radiation absorbing element according to the aforementioned observations, wherein x is in the range of 0.2 to 1.00, y is in the range of 0.2 to 0.8, and x+y is in the range of 0.4 to 1.00.

[0095] 3. The electromagnetic radiation absorbing element according to any one of the foregoing observations, wherein the extinction coefficient E at a given wavelength λ is [value missing] within the wavelength range of 400 nm to 700 nm. λ The logarithm is within ±20% of the extrapolation calculated by the following equation: Where E 400 The extinction coefficient at a wavelength of 400 nm, and E 700 The extinction coefficient is the value at a wavelength of 700 nm.

[0096] 4. The electromagnetic radiation absorbing element according to any one of the foregoing observations, wherein the microcrystals of the crystalline phase are embedded in the amorphous phase, and the volume fraction of the microcrystalline phase is >0.1% and ≤30% by volume, preferably ≤20% by volume, and most preferably ≤10% by volume.

[0097] 5. The electromagnetic radiation absorbing element according to any one of the foregoing observations, wherein, at least in the wavelength range of 350 nm to 700 nm, the specific absorption of the crystalline phase is higher than that of the amorphous phase.

[0098] 6. The electromagnetic radiation absorbing element according to any one of the foregoing observations, wherein the microcrystalline phase comprises microcrystals, the average diameter DC of the microcrystals being in the range of 1 nm to 2000 nm, and the average refractive index NC being in the range of 1.7 to 6.

[0099] 7. The electromagnetic radiation absorbing element according to any one of the foregoing observations, wherein the refractive index NG of the amorphous phase is in the range of 1.45 to 1.65.

[0100] 8. An electromagnetic radiation absorbing element comprising a glass-ceramic phase and an amorphous phase, wherein the volume fraction of the crystalline phase is at least 0.1 vol% and at most 30 vol%, wherein the volume fraction of the amorphous phase is at least 70 vol%, and wherein the crystalline phase is composed of a chemical formula (Fe) x Mn y Mg z The microcrystalline composition of TiO3, wherein x+y+z =1.00, wherein advantageously, x is in the range of 0.2 to 0.8, y is in the range of 0.2 to 0.8, and x+y is in the range of 0.4 to 1.00.

[0101] 9. The glass-ceramic described in Observation 8, where z = 0.00.

[0102] 10. The glass-ceramic according to any one of the foregoing observations, wherein the ratio of the molar amount of TiO2 to the sum of the molar amounts of Fe2O3, MnO2 and MgO in the glass-ceramic is in the range of 0.50 to 2.00.

[0103] 11. The glass-ceramic according to any one of the foregoing observations, wherein the average size of the crystallites is in the range of 1 nm to 2000 nm, particularly 1 nm to 1000 nm, advantageously in the range of 2 nm to 500 nm, particularly 2 nm to 200 nm.

[0104] 12. The glass-ceramic according to any one of the foregoing observations, wherein the glass-ceramic comprises one or more additional crystalline phases, the volume fraction of the one or more additional crystalline phases being in the range of 0.0 vol% to 80 vol% relative to the total volume of the glass-ceramic.

[0105] 13. The glass-ceramic according to any one of the foregoing observations, wherein the volume fraction of the amorphous phase is at least 70% by volume.

[0106] 14. The glass-ceramic according to any one of the foregoing observations, wherein the extinction coefficient of the glass-ceramic is at least 50 / cm over the entire wavelength range of 300 nm to 1400 nm.

[0107] 15. The glass-ceramic according to any one of the foregoing observations, wherein the glass-ceramic comprises components in the amounts (in mol%) shown below: 16. The glass-ceramic according to any one of the foregoing observations, wherein the glass-ceramic comprises components in the amounts (in mol%) shown below: 17. The glass-ceramic according to any one of the foregoing observations, wherein y is at least 0.2, and / or wherein advantageously the amount of MnO2 in the glass-ceramic is at least 0.5 mol.

[0108] 18. The glass-ceramic according to any one of the foregoing observations, wherein the glass-ceramic comprises one or more colorants, the total amount of which is from 50 ppm to 500 ppm in molar terms, said colorant being selected from the group consisting of Cr2O3, V2O5, NiO, CoO and combinations thereof.

[0109] 19. The glass-ceramic according to any one of the foregoing observations, wherein the average coefficient of linear thermal expansion (CTE) is in the range of 3.0 ppm / K to 10.0 ppm / K in the temperature range of 20°C to 300°C.

[0110] 20. The glass-ceramic according to any one of the foregoing observations, wherein the extinction coefficient at a wavelength of 550 nm is at least 200 / cm.

[0111] 21. A method for producing glass-ceramics according to any one of the foregoing observations, the method comprising at least the following steps: a) Providing a starting glass comprising: 1-20 mol% TiO2, Fe2O3 and MnO2, and optionally MgO, wherein the total amount of Fe2O3, MnO2 and MgO is at least 0.6 mol%, wherein advantageously, the step of providing the starting glass includes melting the glass raw material under reducing conditions and cooling the melt to obtain the starting glass; and b) Heat-treating the starting glass to obtain a glass-ceramic, wherein the heat treatment includes heat-treating the starting glass to form the microcrystals at temperature stages, said temperature stages including: at least one stage of 600°C to 700°C, and / or one stage of 700°C to 800°C, and / or one stage of 800°C to 1000°C, advantageously including a combination of at least two said stages.

[0112] 22. The method based on the foregoing observations, wherein reducing conditions are obtained by adding carbohydrates, particularly sugars, to the glass raw materials.

[0113] 23. The method according to any one of the foregoing observations, wherein the formation of the microcrystals is carried out at a temperature of at least 600°C.

[0114] 24. The use of the glass-ceramic according to any one of the foregoing observations in the fields of fiber optic devices, optical filters, and especially electronic components, or as (ultra)thin glass, or cover glass for electronic devices, or cover glass for at least a portion of the housing of electronic devices, or as part of the housing of household appliances.

[0115] The advantages of this invention are that the provided elements and / or the described glass-ceramics absorb electromagnetic radiation very efficiently, especially in the visible spectrum. This provides very high extinction properties. Furthermore, due to the high extinction properties and the substantially linear dependence of the logarithm of extinction on wavelength in the visible spectrum, the provided elements and / or glass-ceramics have a deep black appearance, advantageously without any color shift perceptible to the human eye. Since the elements and / or materials are glass-ceramics, properties such as crystallite size and the amount of crystalline phase in the amorphous phase can be adjusted according to the requirements of the intended use. The provided elements and / or glass-ceramics can be formed using known glass processing methods, especially thermoforming processes.

Claims

1. An electromagnetic radiation absorbing element comprising, or composed of, glass-ceramic, a crystalline phase and an amorphous phase, wherein the extinction coefficient of the glass-ceramic is greater than 20 / cm over the entire wavelength range of 350 nm to 700 nm, preferably greater than 100 / cm over the entire wavelength range of 350 nm to 700 nm, wherein the crystalline phase comprises having the chemical formula (Fe) x Mn y Mg z A microcrystalline ilmenite-type solid solution of TiO3, wherein x is at least 0.2, y is at least 0.2, and x+y+z = 1.

00.

2. The electromagnetic radiation absorbing element according to claim 1, wherein x is in the range of 0.2 to 0.8, y is in the range of 0.2 to 0.8, and x+y is in the range of 0.4 to 1.

00.

3. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the extinction coefficient E at each given wavelength λ in the wavelength range of 400 nm to 700 nm is... λ The logarithm is within ±20% of the extrapolation calculated by the following equation: Where E 400 The extinction coefficient at a wavelength of 400 nm, and E 700 The extinction coefficient is denoted as 700 nm.

4. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the microcrystals of the crystalline phase are embedded in the amorphous phase, and the volume fraction of the microcrystalline phase relative to the total volume of the glass-ceramic is at least 0.1 vol% and at most 30 vol%, preferably ≤20 vol%, most preferably ≤10 vol% or <5 vol%.

5. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein, at least in the wavelength range of 350 nm to 700 nm, the specific absorption of the crystalline phase is higher than that of the amorphous phase.

6. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the crystalline phase comprises microcrystals having: an average diameter DC in the range of 1 nm to 2000 nm as defined in the specification; and an average refractive index NC in the range of 1.7 to 6 at each wavelength in the wavelength range of 350 nm to 700 nm as defined in the specification.

7. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the refractive index NG of the amorphous phase is in the range of 1.45 to 1.65 at each wavelength in the wavelength range of 350 nm to 700 nm.

8. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the volume fraction of the crystalline phase is at least 0.1 vol% and at most 30 vol%, wherein the volume fraction of the amorphous phase is at least 70 vol%, and wherein the crystalline phase is composed of the chemical formula (Fe) x Mn y Mg z The microcrystalline composition of TiO3, wherein x+y+z = 1.00, where x is in the range of 0.2 to 0.8, y is in the range of 0.2 to 0.8, and x+y is in the range of 0.4 to 1.

00.

9. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the amount of MnO2 in the glass ceramic is at least 0.50 mol%, preferably greater than 0.50 mol%.

10. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the glass-ceramic comprises components in the amounts shown below (in mole %): 。 11. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the ratio of the sum of alkali metal oxides and alkaline earth metal oxides to the sum of boron oxide and aluminum oxide is in the range of 0.4 to 0.

6.

12. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein Fe 2+ The ratio to the total Fe content is in the range of 0.3 to 0.

8.

13. The electromagnetic radiation absorbing element according to any one of the preceding claims, wherein the glass ceramic comprises one or more colorants, the total amount of which is from 50 ppm to 500 ppm in molar terms, and the colorant is selected from the group consisting of Cr2O3, V2O5, NiO, CoO and combinations thereof.

14. A method for producing glass ceramics and / or electromagnetic radiation absorbing elements according to any one of the preceding claims, the method comprising at least the following steps: a) Providing a starting glass comprising: 1-20 mol% TiO2, Fe2O3 and MnO2, and optionally MgO, wherein the total amount of Fe2O3, MnO2 and MgO is at least 0.06 mol%, wherein advantageously, the step of providing the starting glass includes melting the glass feedstock under reducing conditions and cooling the melt to obtain the starting glass; and b) Heat-treating the starting glass to obtain the glass-ceramic, wherein the heat treatment includes heat-treating the starting glass to form the microcrystals at temperature stages, the temperature stages including: at least one stage of 600°C to 700°C, and / or one stage of 700°C to 800°C, and / or one stage of 800°C to 1000°C, advantageously including a combination of at least two of the stages.

15. The method of claim 14, wherein the method comprises obtaining reducing conditions by adding carbohydrates, particularly sugars, to the glass raw material.

16. The use of the electromagnetic radiation absorbing element according to any one of claims 1 to 15 in the fields of fiber optic devices and optical filters, or as (ultra)thin glass, or as cover glass, or as a substrate of an electronic device, or as cover glass of at least a portion of an electronic device housing, or as part of a household appliance housing.

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