TRANSPARENT B-QUARTZ GLASS-CERAMICS WITH SPECIFIC TRANSMISSION
20230150860 · 2023-05-18
Assignee
Inventors
US classification
- 501/70
Cpc classification
C03C3/087
CHEMISTRY; METALLURGY
C03C3/078
CHEMISTRY; METALLURGY
C03C10/0027
CHEMISTRY; METALLURGY
International classification
C03C3/087
CHEMISTRY; METALLURGY
C03C3/078
CHEMISTRY; METALLURGY
Abstract
The present invention relates to a transparent lithium aluminosilicate (LAS) glass-ceramic containing a β-quartz solid solution as the main crystalline phase, the composition of which, expressed in percentages by mass of oxides, contains 60 to 67.5% SiO.sub.2, 18 to 22% Al.sub.2O.sub.3, 2.5 to 3.3% Li.sub.2O, 0 to 1.5% MgO, 1 to 3.5% ZnO, 0 to 4% BaO, 0 to 4% SrO, 0 to 2% CaO, 3.1 to 5% TiO.sub.2, 0.4 to 1.3% ZrO.sub.2, 0 to 1% Na.sub.2O, 0 to 1% K.sub.2O, 0 to 5% P.sub.2O.sub.5, 0.02 to 0.1% CoO, 0.05 to 0.25% Fe.sub.2O.sub.3, with (0.74 MgO + 0.19 BaO + 0.29 SrO + 0.53 CaO + 0.48 Na.sub.2O + 0.32 K.sub.2O) / Li.sub.2O < 0.8, and optionally up to 2% of at least one refining agent, the composition being free of V.sub.2O.sub.5 with the exception of unavoidable traces. It also relates to an article, consisting at least in part of a glass-ceramic, chosen in particular from a cooking plate and a glazing. It also relates to a lithium aluminosilicate glass, precursor of the glass-ceramic, and the process for producing the article.
Claims
1. A transparent lithium aluminosilicate (LAS) glass-ceramic containing a β-quartz solid solution as the main crystalline phase, the composition of which, expressed in percentages by mass of oxides, contains: 60 to 67.5% SiO.sub.2, 18 to 22% Al.sub.2O.sub.3, 2.5 to 3.3% Li.sub.2O, 0 to 1.5% MgO, 1 to 3.5% ZnO, 0 to 4% BaO, 0 to 4% SrO, 0 to 2% CaO, 3.1 to 5% TiO.sub.2, 0.4 to 1.3% ZrO.sub.2, 0 to 1% Na.sub.2O, 0 to 1% K.sub.2O, 0 to 3% P.sub.2O.sub.5, 0.02 to 0.1% CoO 0.05 to 0.25% Fe.sub.2O.sub.3 with (0.74 MgO + 0.19 BaO + 0.29 SrO + 0.53 CaO + 0.48 Na.sub.2O + 0.32 K.sub.2O) / Li.sub.2O < 0.8, and optionally up to 2% of at least one refining agent, the composition being free of V.sub.2O.sub.5 with the exception of unavoidable traces.
2. The glass-ceramic as claimed in claim 1, the composition of which contains 2.5 to 3% Li.sub.2O.
3. The glass-ceramic as claimed in claim 1, the composition of which contains at least 0.5% P.sub.2O.sub.5, advantageously from 1 to 3% P.sub.2O.sub.5.
4. The glass-ceramic as claimed in claim 1, the composition of which is free, with the exception of unavoidable traces, of B.sub.2O.sub.3.
5. The glass-ceramic as claimed in claim 1, the composition of which, free from unavoidable traces of As.sub.2O.sub.3 and Sb.sub.2O.sub.3, contains SnO.sub.2 as refining agent, advantageously from 0.05% to 0.6% of SnO.sub.2, very advantageously from 0.15% to 0.4% of SnO.sub.2.
6. The glass-ceramic as claimed in claim 1, having a composition of 0.05% to 0.15% Fe.sub.2O.sub.3.
7. The glass-ceramic as claimed in claim 1, characterized in that it has a coefficient of thermal expansion between ±14×10.sup.- .sup.7K.sup.-1, between 25 and 700° C.
8. The glass-ceramic as claimed in claim 1, characterized in that it has for a thickness of 1 to 8 mm, advantageously 2 to 5 mm, in particular 4 mm, an integrated visible transmission Y, of at least 0.8% but less than 10%, advantageously at least 0.8% but less than 5% and/or; for a thickness of 1 to 8 mm, advantageously 2 to 5 mm, in particular 4 mm, an optical transmission at a wavelength of 950 nm T.sub.950nm of between 40 and 70%, preferably between 50 and 70%, and/or; a percentage of diffusion of less than 12%, advantageously less than 6%, more advantageously less than 2%, and/or in transmission colorimetric coordinates, in the CIExy space, for a D65 illuminant with a 2° observer, which are within the twelfth MacAdam ellipse having as center the point with the following trichromatic coordinates x=0.44 y=0.38 Y=1.8%.
9. The glass-ceramic as claimed in claim 1, characterized in that the composition of which, expressed in percentages by mass of oxides, contains: 1.5 to 3% P.sub.2O.sub.5, 18 to 20% Al.sub.2O.sub.3, 2.7 to 3% Li.sub.2O with (0.74 MgO + 0.19 BaO + 0.29 SrO + 0.53 CaO + 0.48 Na.sub.2O + 0.32 K.sub.2O) / Li.sub.2O < 0.7 and in that it has a coefficient of thermal expansion between ±6×10.sup.-7K.sup.-1, between 25 and 700° C.
10. An article, consisting at least in part of a glass-ceramic as claimed in claim 1, chosen in particular from a cooking plate and a glazing.
11. Use of a glass-ceramic as claimed in claim 1, as a substrate for an element selected from a cooking plate and a glass pane.
12. A lithium aluminosilicate glass, a precursor of a glass-ceramic as claimed in claim 1, the composition of which makes it possible to obtain a glass-ceramic as claimed in claim 1.
13. The glass as claimed in claim 12, having: a liquidus temperature of less than 1400° C. and/or a liquidus viscosity of more than 400 Pa.s, preferably more than 700 Pa.s and/or a viscosity of 30 Pa.s at a temperature of at most 1640° C., preferably at a temperature of at most 1630° C. and/or an electrical resistivity at a viscosity of 30 Pa.s of less than 50 Ωcm, preferably less than 20 Ωcm.
14. A process for producing an article as claimed in claim 10, comprising successively: melting a vitrifiable raw material feedstock, followed by refining the resulting molten glass; cooling the refined molten glass obtained and simultaneously shaping it to the desired shape for the article; and ceramming heat treatment of said shaped glass; characterized in that said feedstock has a composition which makes it possible to obtain a glass-ceramic having the mass composition stated in claim 1 and in that the ceramming temperature is at most 900° C.
15. The process as claimed in claim 14, characterized in that said vitrifiable raw material feedstock, which is free except for unavoidable traces of As.sub.2O.sub.3 and Sb.sub.2O.sub.3, contains SnO.sub.2 as refining agent, advantageously from 0.05 to 0.6% SnO.sub.2.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0129]
[0130]
[0131]
[0132]
EXAMPLES
[0133] Process for producing glasses: One-kilogram batches of raw materials were prepared. The raw materials, in the proportions (proportions expressed in % by mass of oxides) reported in the first part of the tables, were carefully mixed. The mixtures were placed in platinum crucibles for melting. The crucibles containing said mixtures were then placed in a furnace preheated to 1550° C. This furnace is heated with MoSi electrodes. The crucibles have undergone in said furnace a melting cycle of the following type: [0134] holding, for 30 min, at 1550° C., [0135] temperature rise from 1550° C. to 1650° C. in 1 h, and [0136] holding for 5.5 h at 1650° C.
[0137] The crucibles were then taken out of the furnace and the molten glass poured onto a preheated steel plate. It was rolled to a thickness of 6 mm. Glass plates were thus obtained. They were annealed at 650° C. for 1 hour and then gently cooled.
[0138] The results obtained in this way at the laboratory scale are completely transposable to the industrial scale.
[0139] Properties: The properties of the glass obtained are indicated in the second part of the tables below.
[0140] T.sub.liq (°C) is the temperature of the liquidus. In fact, the liquidus is given by a range of temperatures and associated viscosities: the highest temperature corresponds to the minimum temperature at which no crystals were experimentally observed, the lowest temperature to the maximum temperature at which crystals were experimentally observed. The experiments were carried out on volumes of precursor glass of about 0.5 cm.sup.3, maintained for 17 h at the test temperature and quickly cooled to room temperature. Observations were made by optical microscopy.
[0141] The viscosities were measured with a rotational viscometer. T(30 Pa.s) (°C) corresponds to the temperature at which the viscosity of the glass was 30 Pa.s (= 300 poise). Using these viscosity data and the minimum and maximum liquidus temperatures, the viscosity range of the liquidus was calculated.
[0142] The resistivity of the glass was measured during viscosity measurements at high temperature on a 1 cm thickness of molten glass using an RLC bridge. The resistivity measured at the temperature at which the viscosity is 30 Pa.s (ρ (30 Pa.s)) is given in the tables.
[0143] The ceramming cycles carried out in a static furnace (in ambient air atmosphere) are specified below:
[0144] KV1: [0145] heating up to 750° C. at a heating rate of 10° C./min; [0146] holding at this temperature (= 750° C.) for 24 minutes; [0147] temperature rise from 750° C. to 860° C. at a heating rate of 10° C./min; [0148] holding at this temperature (= 860° C.) for 10 minutes; [0149] cooling to ambient temperature at a rate depending on the inertia of the oven.
[0150] The total duration of this cycle is 118 min (excluding cooling).
[0151] KV 19: [0152] heating up to 800° C. at a heating rate of 10° C./min; [0153] holding at this temperature (= 800° C.) for 24 minutes; [0154] temperature rise from 800° C. to 860° C. at a heating rate of 10° C./min; [0155] holding at this temperature (= 860° C.) for 10 minutes; [0156] cooling to ambient temperature at a rate depending on the inertia of the oven.
[0157] The total duration of this cycle is 118 min (excluding cooling).
[0158] Industrially it is believed that these cycles could be significantly shorter as a much higher rate of temperature rise to 750° C. could probably be achieved, especially if the ceramming is carried out in a roller earth.
[0159] A35: [0160] rapid rise in temperature up to 500° C., [0161] temperature rise from 500 to 650° C., at a heating rate of 23° C./min, [0162] temperature rise from 650° C. to 820° C., at a heating rate of 6.7° C./min, [0163] temperature rise from 820° C. to 920° C., at a heating rate of 15° C./min, [0164] holding at this temperature Tmax (= 920° C.) for 7 minutes, [0165] cooling to 850° C. at 35° C./min, [0166] cooling down to ambient temperature at a rate depending on the inertia of the furnace.
[0167] Coefficients of thermal expansion (CTEs) were measured with a high-temperature dilatometer (DIL 402C, Netzsch) at a heating rate of 3° C./min on rod-shaped glass-ceramic samples.
[0168] On polished 4 mm thick samples, total and diffuse transmission measurements were performed using a Varian spectrophotometer (model Cary 500 Scan), equipped with an integrating sphere. Optical properties such as colorimetric coordinates (x, y), integrated transmission (Y (%)) in the visible range (between 380 and 780 nm) and the level of haze (diffusion or haze (%)) according to ASTM D 1003-13 of Apr. 15, 2013 are given under illuminant D65 with 2° observer. A Y value of less than 10% is recommended, preferably less than 5%, much preferable less than 2%, to conceal the inductors and other technical components arranged under the cooktops. A Y value of at least 0.8% is also recommended. A haze level of less than 12%, preferably less than 6%, more preferably less than 2%, is recommended to ensure good visibility of the light emitted by the LEDs arranged under the cooktops. The colorimetric coordinates (x,y) measured using the EGO Lite TC LED as illuminant have also been reported. Transmission values at 950 nm (T.sub.950nm) are also shown in the tables. An optical transmission for a wavelength of 950 nm (T.sub.950nm) of between 40 and 70%, and even more preferably between 50 and 70%, which allows the use of infra-red electronic control keys, transmitting and receiving at this wavelength, is also recommended.
[0169] X-ray diffraction analyses were performed. The percentages of crystalline phases (expressed as a mass percentage of the total crystallized fraction) were evaluated by a Rietveld method as well as the average size of β-quartz crystallites. In the case of Example 1, the percentage of glassy phase was also determined by a standard addition method. It is 40% by weight after ceramming with KV1 cycle.
[0170] Examples 1 to 25 illustrate the present application.
[0171] Compositions and properties of the glasses are reported in tables 1-6.
[0172] The properties of the resulting glass-ceramics are shown in tables 1- 6 in the case of ceramming with cycle KV1 and in table 7 in the case of ceramming with cycle KV 19. In the case of the P.sub.2O.sub.5 containing glasses, ceramming with the KV 19 cycle leads generally to lower haze than KV 1.
[0173] Examples 1 to 6 are the preferred examples because it is with the corresponding glass-ceramics that the light emitted by the white LEDs appears the whitest. Of these, Examples 3, 4, 5 and 6 are particularly preferred because they also have low expansion (≤ 6×10.sup.-7K.sup.-1 between 25 and 700° C.) after ceramming with cycles KV1 and therefore could be used with radiant heaters. Example 5 is the most preferred because in addition it displays a visible integrated transmission lower than 2%.
[0174] Examples 3, 4 and 5 present the same base glass composition but differ only by their level of Fe.sub.2O.sub.3 and CoO.
[0175] Examples A to F (from Table 8) are comparative examples.
[0176] In Comparative Example A, the coloring is obtained using chromium and vanadium oxides and their TiO.sub.2 content is less than 3%. Consequently, the colorimetric coordinates are outside the objective.
[0177] The Comparative Examples B and C correspond to the same composition with two different ceramming treatments (KV1 and A35). The TiO.sub.2 content of the glass is less than 3%. As a consequence, the transmission, Y, is too high and the colorimetric coordinates outside the objective, regardless of the ceramming cycle.
[0178] The Comparative Example D contains a high Li.sub.2O content. As a result, the transmission is relatively high and the color coordinates are outside the objective.
[0179] The Comparative Example E contains a low Li.sub.2O content. As a result, the expansion of the glass-ceramic is too high and the color coordinates are outside the objective.
[0180] The Comparative Example F does not contain ZrO.sub.2. As a result, the expansion is too high and the haze unacceptable, probably due to insufficient nucleation.
[0181] Tables 1 to 7 (Examples 1 to 25 according the present application) and 8 (Comparative Examples A, B, C, D, E and F) are presented below.
TABLE-US-00001 Composition (wt %) 1 2 3 4 SiO.sub.2 64.7 65.45 62.28 62.28 P.sub.2O.sub.5 2.27 2.27 Al.sub.2O.sub.3 20.34 19.68 19.06 19.06 Li.sub.2O 2.9 2.90 2.83 2.83 MgO 0.69 1.46 0.82 0.82 ZnO 3.19 1.96 3.1 3.1 BaO 2.47 2.77 2.68 2.68 CaO 0.44 0.44 0.97 0.97 TiO.sub.2 3.36 3.43 4.5 4.5 ZrO.sub.2 0.67 0.67 0.66 0.66 Na.sub.2O 0.61 0.61 0.2 0.2 K.sub.2O 0.2 0.2 0.2 0.2 SnO.sub.2 0.3 0.3 0.29 0.29 Fe.sub.2O.sub.3 0.08 0.060 0.10 0.080 CoO 0.05 0.07 0.05 0.07 (0.74MgO+0.19BaO+0.29SrO+0.53 CaO+0.48Na.sub.2O+0.32K.sub.2O)/Li.sub.2O 0.54 0.76 0.63 0.63 T(30 Pa.s) (°C) 1616 1625 1578 Resistivity at 30 Pa.s (Ω.cm) 5 4.8 5.7 Tliq (°C) 1280-1300 1235-1252 1237-1260 Viscosity at Tliq (Pa.s) 1060-1430 2500 - 3300 1300-1800 Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 7.4 12.3 5.3 5.9 CTE(25-300° C.) (× 10.sup.-7/K) 5.4 10 4.3 5.1 T950nm (%) 53.7 54.7 48.5 53.2 Illuminant D65 Y (%) 1.86 1.73 2.68 2.88 Diffusion (Haze) (%) 3.05 5.1 0.9 1.5 x 0.4516 0.4503 0.4403 0.4312 y 0.3853 0.3897 0.3905 0.385 Illuminant EGO Lite TC Y (%) 1.74 1.61 2.55 2.73 x 0.401 0.3975 0.3943 0.3825 y 0.3796 0.3845 0.3833 0.3737 X-Ray diffraction Mean size of β-quartz solid solution crystallites (nm) 53 58 48 β-quartz solid solution (%) 90 96 95 β-Spodumene- (%) 5 4 1 Spinel solid solution (%) 5 4
TABLE-US-00002 Composition (wt %) 5 6 7 8 SiO.sub.2 62.245 62.09 63.88 62.83 P.sub.2O.sub.5 2.27 2.26 2.13 2.12 Al.sub.2O.sub.3 19.06 19.01 19.65 19.59 Li.sub.2O 2.83 2.82 2.64 2.63 MgO 0.82 0.82 0.39 0.39 ZnO 3.1 3.1 3.21 3.20 BaO 2.68 2.67 2.42 2.41 CaO 0.97 0.97 0.44 0.44 TiO.sub.2 4.5 4.49 3.31 4.50 ZrO.sub.2 0.66 0.91 0.67 0.68 Na.sub.2O 0.2 0.2 0.60 0.59 K.sub.2O 0.2 0.2 0.2 0.2 SnO.sub.2 0.29 0.29 0.29 0.29 Fe.sub.2O.sub.3 0.120 0.12 0.10 0.060 CoO 0.055 0.055 0.07 0.07 (0.74MgO+0.19BaO+0.29SrO+0.5 3CaO+0.48Na.sub.2O+0.32K.sub.2O)/Li.sub.2O 0.63 0.63 0.51 0.50 T(30 Pa.s) (°C) 1638 Resistivity at 30 Pa.s (Ω.cm) 4.6 Tliq (°C) 1240-1260 Viscosity at Tliq (Pa.s) 2600 - 3600 Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 5.8 6 7.6 8 CTE(25-300° C.) (× 10.sup.-7/K) 5.2 5.4 6.7 7.4 T950nm (%) 43.9 49.7 52.5 60.8 Illuminant D65 Y (%) 1.48 3 1.97 3.2 Diffusion (Haze) (%) 1.42 0.8 3.4 3.02 x 0.4596 0.4445 0.449 0.4246 y 0.3985 0.3796 0.3764 0.3864 Illuminant EGO Lite TC Y (%) 1.4 2.84 1.84 2.97 x 0.4125 0.3958 0.3952 0.3697 y 0.3976 0.3713 0.3674 0.3521 X-Ray diffraction Mean size of des β-quartz solid solution crystallites (nm) 48 β-quartz solid solution (%) 94 β-Spodumene- (%) Spinel solid solution (%) 6
TABLE-US-00003 Composition (wt %) 9 10 11 12 SiO.sub.2 65.13 63.61 64.475 64.945 P.sub.2O.sub.5 2.13 Al.sub.2O.sub.3 20.41 19.65 19.54 19.81 Li.sub.2O 2.90 2.9 2.90 3.22 MgO 1.30 0.39 1.45 1.47 ZnO 1.96 3.21 1.95 1.98 BaO 2.48 2.41 2.75 2.78 CaO 0.44 0.44 0.44 0.45 TiO.sub.2 3.43 3.32 4.62 3.45 ZrO.sub.2 0.67 0.68 0.67 0.68 Na.sub.2O 0.61 0.6 0.61 0.62 K.sub.2O 0.2 0.2 0.2 0.2 SnO.sub.2 0.30 0.29 0.30 0.3 Fe.sub.2O.sub.3 0.10 0.10 0.060 0.060 CoO 0.07 0.07 0.035 0.035 (0.74MgO+0.19BaO+0.29SrO+0.5 3CaO+0.48Na.sub.2O+0.32K.sub.2O)/Li.sub.2O 0.7 0.46 0.75 0.69 T(30 Pa.s) (°C) 1597 1610 Resistivity at 30 Pa.s (Ω.cm) 5.3 4.3 Tliq (°C) 1244-1260 1225-1244 Viscosity at Tliq (Pa.s) 1500-2000 2300-3100 Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 12.3 3.5 13.3 9.9 CTE(25-300° C.) (× 10.sup.-7/K) 10.5 2.4 11.6 7.5 T950nm (%) 55.3 50.3 55.4 47.7 Illuminant D65 Y (%) 1.81 1.67 2.73 1.83 Diffusion (Haze) (%) 4.01 2.51 2.05 3.1 x 0.4477 0.4586 0.4392 0.4373 y 0.3527 0.3823 0.3971 0.4215 Illuminant EGO Lite TC Y (%) 1.66 1.55 2.61 1.77 x 0.3863 0.4057 0.3949 0.399 y 0.3379 0.3763 0.4004 0.4209 X-Ray diffraction Mean size of des β-quartz solid solution crystallites (nm) 50 β-quartz solid solution (%) 98 β-Spodumene- (%) 2 Spinel solid solution (%)
TABLE-US-00004 Composition (wt %) 13 14 15 16 SiO.sub.2 64.065 64.045 63.845 62.70 P.sub.2O.sub.5 2.26 Al.sub.2O.sub.3 19.60 19.60 19.54 19.16 Li.sub.2O 2.91 2.91 2.90 2.85 MgO 1.15 1.15 0.84 1.42 ZnO 2.58 2.58 3.19 1.92 BaO 2.75 2.75 2.75 2.69 CaO 0.44 0.44 0.44 0.97 TiO.sub.2 4.63 4.63 4.62 4.53 ZrO.sub.2 0.67 0.67 0.67 0.66 Na.sub.2O 0.62 0.61 0.61 0.20 K.sub.2O 0.2 0.2 0.2 0.20 SnO.sub.2 0.3 0.3 0.30 0.29 Fe.sub.2O.sub.3 0.060 0.080 0.060 0.10 CoO 0.035 0.035 0.035 0.05 (0.74MgO+0.19BaO+0.29SrO+0.5 3CaO+0.48Na.sub.2O+0.32K.sub.2O)/Li.sub.2O 0.68 0.67 0.60 0.79 T(30 Pa.s) (°C) 1585 Resistivity at 30 Pa.s (Ω.cm) 5.3 Tliq (°C) 1240-1280 Viscosity at Tliq (Pa.s) 1000-1900 Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 11.6 12.3 10.2 9.8 CTE(25-300° C.) (× 10.sup.-7/K) 9.6 10.3 8 8.8 T950nm (%) 51.6 43.1 46.4 59.5 Illuminant D65 Y (%) 2.23 0.86 1.46 6.32 Diffusion (Haze) (%) 3.02 2.3 4.25 0.41 x 0.4465 0.471 0.4591 0.4102 y 0.4211 0.424 0.4341 0.3557 Illuminant EGO Lite TC Y (%) 2.15 0.82 1.41 6.04 x 0.4072 0.4296 0.4223 0.3626 y 0.4231 0.4341 0.4434 0.3386
TABLE-US-00005 Composition (wt %) 17 18 19 20 SiO.sub.2 62.655 64.69 64.69 64.66 P.sub.2O.sub.5 2.24 Al.sub.2O.sub.3 19.15 20.34 20.34 20.34 Li.sub.2O 2.85 2.90 2.90 2.90 MgO 1.42 0.68 0.68 0.69 ZnO 1.91 3.19 3.19 3.19 BaO 2.69 2.47 2.47 2.47 CaO 0.97 0.44 0.44 0.44 TiO.sub.2 4.53 3.36 3.36 3.36 ZrO.sub.2 0.66 0.67 0.67 0.67 Na.sub.2O 0.20 0.61 0.61 0.61 K.sub.2O 0.20 0.2 0.2 0.2 SnO.sub.2 0.29 0.3 0.3 0.3 Fe.sub.2O.sub.3 0.20 0.08 0.10 0.10 CoO 0.035 0.07 0.05 0.07 (0.74MgO+0.19BaO+0.29SrO+0.5 3CaO+0.48Na.sub.2O+0.32K.sub.2O)/Li.sub.2O 0.78 0.54 0.54 0.54 Properties T(30 Pa.s) (°C) Resistivity at 30 Pa.s (Ω.cm) Tliq (°C) 1284 - 1300 Viscosity at Tliq (Pa.s) Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 9.5 7.9 8.1 8.4 CTE(25-300° C.) (× 10.sup.-7/K) 8.7 5.9 6.1 6.2 T950nm (%) 45.8 50.7 48.2 49.3 Illuminant D65 Y (%) 3.03 0.92 1.03 0.81 Diffusion (Haze) (%) 0.48 3.18 3.25 3.25 x 0.4697 0.4726 0.4778 0.4786 y 0.3865 0.3757 0.3931 0.3864 Illuminant EGO Lite TC Y (%) 2.87 0.84 0.95 0.74 x 0.4226 0.413 0.4264 0.4216 y 0.3858 0.3723 0.3964 0.3386 Diffraction X Mean size of des β-quartz solid solution crystallites 55 β-quartz solid solution (%) 91 β-Spodumene- (%) 4 Spinel solid solution (%) 5
TABLE-US-00006 Composition (wt %) 21 22 23 24 25 SiO.sub.2 64.33 62.30 61.49 61.025 60.815 .sub.2O.sub.5 2.25 1.06 2.26 2.25 Al.sub.2O.sub.3 20.34 19.04 20.84 20.41 20.39 Li.sub.2O 2.90 2.83 2.87 2.81 2.81 MgO 0.69 0.82 0.83 0.81 0.81 ZnO 3.19 3.10 3.15 3.08 3.08 BaO 2.47 2.67 2.71 2.65 2.65 CaO 0.44 0.97 0.98 0.97 0.97 TiO.sub.2 3.36 4.50 4.56 4.47 4.46 ZrO.sub.2 1 0.66 0.67 0.65 0.90 Na.sub.2O 0.61 0.20 0.20 0.20 0.20 K.sub.2O 0.2 0.20 0.20 0.20 0.20 SnO.sub.2 0.3 0.29 0.29 0.29 0.29 Fe.sub.2O.sub.3 0.10 0.10 0.10 0.12 0.12 CoO 0.07 0.070 0.050 0.055 0.055 (0.74MgO+0.19BaO+0.29 SrO+0.53CaO+0.48Na.sub.2O+ 0.32K.sub.2O)/Li.sub.2O 0.54 0.63 0.63 0.63 0.63 Properties after ceramming with KV1 cycle CTE(25-700° C.) (× 10.sup.-7/K) 7.5 5.8 10.4 8.1 8 CTE(25-300° C.) (× 10.sup.-7/K) 5.2 5.1 8.9 7 6.9 T950nm (%) 61.9 51.6 48.6 48.5 50.6 Illuminant D65 Y (%) 4.18 2.65 1.32 1.7 2.3 Diffusion (Haze) (%) 2.43 1.1 1.51 1 0.6 x 0.4334 0.4318 0.4667 0.4579 0.4538 y 0.3288 0.3741 0.3965 0.3779 0.369 Illuminant EGO Lite TC Y (%) 3.85 2.5 1.23 1.58 2.16 x 0.373 0.3803 0.4168 0.4049 0.3999 y 0.3097 0.3606 0.3984 0.3726 0.3612
TABLE-US-00007 properties of glass-ceramics after ceramming with cycle K19 Example 3 4 5 6 22 24 25 CTE(25-700° C.) (× 10.sup.-7/K) 6.1 5.9 6.1 5.8 CTE(25-300° C.) (× 10.sup.-7/K) 5.5 5.2 5.4 5.2 T950nm (%) 46.8 53.1 43.9 47.7 50.8 46 47.7 Illuminant EGO Lite TC Y (%) 2.18 2.8 1.55 2.43 2.32 1.2 1.5 x 0.3985 0.3787 0.4068 0.3995 0.3826 0.412 0.4114 y 0.392 0.3707 0.3945 0.3803 0.3659 0.3817 0.3738 Illuminant D65 Y (%) 2.2 2.98 1.64 2.56 2.46 1.3 1.64 Diffusion (Haze) (%) 0.4 0.7 0.7 0.4 0.6 0.7 0.4 x 0.4436 0.4273 0.4536 0.4472 0.4335 0.4645 0.465 y 0.3971 0.3834 0.3973 0.3866 0.3782 0.3841 0.3776 Diffraction X Mean size of des β-quartz solid solution crystallites (nm) 44 β-quartz solid solution (%) 95 β-Spodumene-(%) 1 Spinel solid solution (%) 4
TABLE-US-00008 Composition (wt %) A B C D E F SiO.sub.2 63.84 64.54 64.54 64.81 65.58 66.1 P.sub.2O.sub.5 2.12 Al.sub.2O.sub.3 19.52 20.34 20.34 20.8 20.41 19.68 Li.sub.2O 2.62 2.9 2.9 3.74 2.45 2.52 MgO 0.39 0.69 0.69 0.37 1.30 1.46 ZnO 3.2 3.19 3.19 1.53 1.96 1.97 BaO 2.41 2.47 2.47 2.48 2.48 2.77 CaO 0.44 0.44 0.44 0.46 0.44 0.46 TiO.sub.2 2.85 2.85 2.85 3.84 3.43 3.86 ZrO.sub.2 1.35 1.3 1.3 0.7 0.67 Na.sub.2O 0.59 0.61 0.61 0.6 0.61 0.61 K.sub.2O 0.2 0.2 0.2 0.2 0.2 0.2 SnO.sub.2 0.29 0.3 0.3 0.3 0.3 0.3 Fe.sub.2O.sub.3 0.12 0.1 0.1 0.1 0.1 CoO / 0.07 0.07 0.07 0.07 0.07 V.sub.2O.sub.5 0.04 Cr.sub.2O.sub.3 0.02 (0.74MgO+0.19BaO+0.29SrO +0.53CaO+0.48Na.sub.2O+0.32K.sub.2 O)/Li.sub.20 0.48 0.52 0.52 0.34 0.80 0.85 cycle A35 A35 KV1 KV1 KV1 KV1 Properties CTE(25-700° C.) (× 10.sup.-7/K) 3.3 3.7 25.4 33.8 CTE(25-300° C.) (× 10.sup.-7/K) 3.1 1.8 24.5 32.6 Illuminant D65 Y (%) 0.87 16.2 10.52 5.62 9.2 3.87 Diffusion (Haze) (%) 1.01 0.54 3.03 0.43 8.2 26.94 x 0.6068 0.3212 0.3875 0.3936 0.3529 0.3985 y 0.3763 0.2253 0.2755 0.291 0.3509 0.4133 Illuminant EGO Lite TC Y (%) 15.34 9.72 5.19 x 0.2791 0.3376 0.3337 y 0.2031 0.2628 0.2635 Diffraction X Mean size of β-quartz solid solution crystallites (nm) 60 β-quartz solid solution (%) 93 β-Spodumene- (%) Spinel solid solution (%) 7
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[0183] Consequently, to let the light emitted by white LEDs pass through, significant transmission is required in both areas. Thus, it is not possible to use vanadium oxide which leads to high absorption between about 400 and 550 nm and very low absorption above 550 nm. It is preferable not to use chromium oxide which leads to strong absorption between 400 and 450 nm.
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