JP7350298B2 - Method for manufacturing ceramic composites - Google Patents

Description

The present invention relates to a method for manufacturing a ceramic composite, and particularly to a method for manufacturing a ceramic composite having a lamellar structure of two oxide phases, a Y ₃ Al ₅ O ₁₂ phase and an Al ₂ O ₃ phase.

Currently, light emitting diodes (LEDs) and semiconductor lasers that emit blue light are used as light sources, and a part of the blue light is wavelength-converted into yellow light using a wavelength conversion member, resulting in color mixing of blue light and yellow light. Illumination devices that emit white light are becoming popular. In such lighting devices, one has been proposed in which a YAG (Y ₃ Al ₅ O ₁₂ )-based phosphor material is used for the wavelength conversion member, and phosphor powder is contained in resin or glass.

Further, Patent Documents 1 and 2 propose a ceramic composite having a lamellar structure in which a Y ₃ Al ₅ O ₁₂ phase and an Al ₂ O ₃ phase are continuously intertwined with each other three-dimensionally as a eutectic. . In such ceramic composites described in Patent Documents 1 and 2, the wavelength of blue light is converted into yellow light using 12 Y ₃ Al ₅ O _phases , and ₁₂ Y ₃ Al ₅ O phases and ₃ Al ₂ O phases are used. Blue light and yellow light are scattered at the interface, and white can be obtained by mixing colors.

Patent No. 4609319 Patent No. 5246376

However, in Patent Documents 1 and 2, ceramic composites are manufactured using the Bridgman method as a unidirectional solidification method, and the moving speed of the crucible is set at 1 to 20 mm/hour, so that the Y ₃ Al ₅ O ₁₂ phase and There was a limit to the refinement of the Al ₂ O ₃ phase. In addition, the Bridgman method creates colony structures due to disturbances at the solid-liquid interface. Furthermore, it was also difficult to control the sizes of the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase to obtain a uniform lamellar structure throughout the ceramic composite.

Therefore, the present invention was made in view of the above-mentioned conventional problems, and provides a method for manufacturing a ceramic composite that can control the size of a lamellar structure that uniformly scatters primary light and wavelength-converted secondary light. The purpose is to provide

In order to solve the above problems, the method for manufacturing a ceramic composite of the present invention includes accommodating a plurality of dies having slits and having their longitudinal directions parallel to each other in a crucible made of molybdenum or tungsten . a step of charging a raw material containing at least aluminum oxide, yttrium oxide, magnesium oxide, and cerium oxide into a crucible; a step of heating the crucible to melt the raw material in the crucible to prepare a melt; forming a melt pool in which the melt is stored above the slit through a slit; bringing a seed crystal into contact with the melt pool; and pulling the seed crystal at a rate of 0.9 mm/hour or more and 400 mm/hour or less; The first phase, Y ₃ Al ₅ O ₁₂ phase, and the second phase, Al 2 _O 3 _phase , exist as a eutectic, and the first phase and the second phase are A ceramic composite having a lamellar structure intertwined three-dimensionally with each other is raised with a molybdenum or tungsten content of 1 mol/ppm or more and 30,000 mol/ppm or less and a thickness of 0.1 mm or more and 4.0 mm or less. Features.

In the method for manufacturing a ceramic composite of the present invention, the lamella spacing between the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase can be controlled, and the primary light and the wavelength-converted secondary light can be uniformly distributed. A scattering ceramic composite can be obtained. Furthermore, it is possible to maintain a uniform lamella interval for each pulling speed of the seed crystal.

Further, in one aspect of the present invention, the interface temperature of the melt in the melt pool is constant during the pulling process.

The present invention can provide a method for manufacturing a ceramic composite that can control the size of a lamellar structure that uniformly scatters primary light and wavelength-converted secondary light.

1 is a schematic configuration diagram showing an apparatus for manufacturing a ceramic composite using the EFG method. (a) It is a top view showing typically an example of the die concerning an embodiment of the present invention. (b) It is a front view of the same figure (a). (c) It is a side view of the same figure (a). (a) It is an explanatory view showing an example of a seed crystal concerning an embodiment of the present invention. (b) is an explanatory diagram showing another example of the seed crystal according to the embodiment of the present invention. (c) It is an explanatory view showing still another example of the seed crystal concerning an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the positional relationship between a seed crystal and a partition plate in an embodiment of the present invention. (a) It is a front view schematically showing the positional relationship between a seed crystal and a partition plate in an embodiment of the present invention. (b) It is a front view showing how a part of the seed crystal is melted in the embodiment of the present invention. (a) In a seed crystal according to an embodiment of the present invention, it is an explanatory diagram showing a seed crystal whose lower side has a comb-teeth shape. (b) In the seed crystal according to the embodiment of the present invention, it is an explanatory view showing a seed crystal whose lower side is saw-shaped. FIG. 1 is a perspective view schematically showing a spreading process of a ceramic composite according to an embodiment of the present invention. FIG. 1 is a perspective view partially showing a plurality of ceramic composites according to an embodiment of the present invention obtained by an EFG method. It is a micrograph showing the surface of ceramic composite 2 obtained by the EFG method. It is a micrograph showing the lamellar structure when changing the pulling speed in the EFG method, and shows the case where the pulling speed is low. It is a micrograph showing the lamellar structure when the pulling speed in the EFG method is changed, and shows the case where the pulling speed is medium. It is a micrograph showing the lamellar structure when the pulling speed in the EFG method is changed, and shows the case where the pulling speed is high. It is a graph showing the relationship between the pulling speed and the lamella spacing in Examples 1, 2, 4, 6, 9, and 11 in which the Ce concentration is 0.5 mol%. It is a perspective view which shows another form of the growth process of a ceramic composite by an EFG method.

Embodiments of the present invention will be described in detail below with reference to the drawings. Identical or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. FIGS. 1 to 8 are diagrams illustrating a plurality of ceramic composites and a manufacturing method thereof according to an embodiment of the present invention.

As shown in FIG. 1, a ceramic composite manufacturing apparatus 1 includes a growth container 3 for growing a ceramic composite 2 and a pulling container 4 for pulling up the grown ceramic composite 2. -Grow the ceramic composite 2 by the fed.Growth method.

The growth container 3 includes a crucible 5, a crucible drive unit 6, a heater 7, an electrode 8, a die 9, and a heat insulator 10. The crucible 5 is made of molybdenum or tungsten and melts the raw material. The crucible drive unit 6 rotates the crucible 5 with its vertical direction as an axis. Heater 7 heats crucible 5. Further, the electrode 8 energizes the heater 7 . The die 9 is installed in the crucible 5 and determines the shape of the liquid surface of the raw material melt (hereinafter simply referred to as "melt" as needed) 21 when pulling up the ceramic composite 2. Further, the heat insulating material 10 surrounds the crucible 5, the heater 7, and the die 9.

Furthermore, the growth container 3 includes an atmospheric gas inlet 11 and an exhaust port 12. The atmospheric gas inlet 11 is an inlet for introducing, for example, argon gas as an atmospheric gas into the growth container 3, and prevents the crucible 5, the heater 7, and the die 9 from being consumed by oxidation. On the other hand, the exhaust port 12 is provided to exhaust the inside of the growth container 3.

The pulling container 4 includes a shaft 13, a shaft drive unit 14, a gate valve 15, and a substrate inlet/outlet 16, and pulls up a plurality of plate-shaped ceramic composites 2 grown from a seed crystal 17. Shaft 13 holds seed crystal 17 . Further, the shaft drive unit 14 moves the shaft 13 up and down toward the crucible 5, and also rotates the shaft 13 about the up and down direction. The gate valve 15 partitions the growth container 3 and the pulling container 4. Further, the substrate entrance/exit 16 allows the seed crystal 17 to be taken in and out.

Note that the manufacturing apparatus 1 also has a control section (not shown), and this control section controls the rotation of the crucible drive section 6 and the shaft drive section 14.

Next, the die 9 will be explained. The die 9 is made of molybdenum and has a large number of partition plates 18 as shown in FIG. As an example of dies, FIG. 2 shows a case where 30 partition plates 18 and 15 dies 9 are formed. The partition plates 18 have the same flat plate shape and are arranged in parallel to each other so as to form a minute gap (slit) 19, thereby forming one die 9. The slit 19 is provided over almost the entire width of the die 9. Furthermore, since the plurality of dies 9 have the same shape and are arranged in parallel at predetermined intervals so that their longitudinal directions are parallel to each other, a plurality of slits 19 are provided. A slope 30 is formed on the top of each partition plate 18, and an acute-angled opening 20 is formed by arranging the slopes 30 facing each other. The slits 19 also have the role of causing the melt 21 to rise from the lower end of each die 9 to the opening 20 by capillary action.

The raw material introduced into the crucible 5 is melted (raw material melt) based on the temperature rise of the crucible 5, and becomes a melt 21. A part of this melt 21 enters the slit 19 of the die 9, rises within the slit 19 based on capillarity as described above, and is exposed from the opening 20, where the raw material melt pool 22 is formed (see FIG. 5(a)). In the EFG method, the ceramic composite 2 grows according to the shape of the melt surface formed in the raw material melt pool (hereinafter referred to as "melt pool" as necessary) 22. In the die 9 shown in FIG. 2, the shape of the melt surface is an elongated rectangle, so that a flat ceramic composite 2 is manufactured.

Next, the seed crystal 17 will be explained. As shown in FIGS. 1, 4, and 5, in this embodiment, a flat plate-shaped ceramic composite substrate is used as the seed crystal 17. Furthermore, the seed crystal 17 is arranged so that the plane direction of the seed crystal 17 and the longitudinal direction of the die 9 are orthogonal to each other at an angle of 90 degrees. Furthermore, since the seed crystal 17 and the ceramic composite 2 are also perpendicular to each other at an angle of 90°, the side surface of the ceramic composite 2 is shown in FIG.

If the contact area of the seed crystal 17 with the substrate holder (not shown) at the lower part of the shaft 13 is large, the seed crystal 17 will be deformed due to stress due to the difference in coefficient of thermal expansion, and may be damaged in some cases. On the other hand, the fixation of the seed crystal 17 may loosen due to the difference in thermal expansion coefficient. Therefore, it is preferable that the contact area between the seed crystal 17 and the substrate holder be small. Further, the seed crystal 17 needs to have a substrate shape that can be securely fixed to the substrate holder.

FIG. 3 is a diagram showing an example of the substrate shape of the seed crystal 17. Among these, in FIGS. 12A and 12B, a notch 23 is provided in the upper part of the seed crystal 17. By using these notches 23, for example, it is possible to insert U-shaped substrate holders from below the two notches 23 to securely hold the seed crystal 17 while reducing the contact area. Become.

Further, as shown in FIG. 3(c), a cutout hole 24 may be provided inside the seed crystal 17. By using these notched holes 24, for example, locking claws are inserted into the two notched holes 24 to securely hold the seed crystal 17 while reducing the contact area between the substrate holder and the seed crystal 17. becomes possible.

Next, a method for manufacturing the ceramic composite 2 using the manufacturing apparatus 1 will be described. First, granulated raw material powders that are the raw materials for the ceramic composite (for example, 64.71% by weight of aluminum oxide, 35.02% by weight of yttrium oxide, 0.003% by weight of magnesium oxide, and 0.0% by weight of cerium oxide). A predetermined amount of powder (containing 27% by weight) is put into the crucible 5 in which the die 9 is housed. The raw material powder may contain compounds or elements other than those mentioned above, depending on the purity or composition of the ceramic composite to be manufactured.

Subsequently, in order to prevent crucible 5, heater 7, or die 9 from being consumed by oxidation, the inside of growth container 3 is replaced with argon gas to keep the oxygen concentration below a predetermined value.

Next, the crucible 5 is heated to a predetermined temperature by the heater 7, and the raw material powder is melted. Since the melting point of aluminum oxide is approximately 2050°C to 2072°C, the heating temperature of the crucible 5 is set to a temperature higher than the melting point (for example, 2100°C). After a while after heating, the raw material powder melts and a raw material melt 21 is prepared. Further, a part of the melt 21 rises through the slit 19 of the die 9 due to capillary action and reaches the surface of the die 9, and a melt pool 22 is formed above the slit 19.

Next, as shown in FIGS. 4 and 5, the seed crystal 17 is lowered while holding the seed crystal 17 at an angle perpendicular to the longitudinal direction of the melt pool 22 above the slit 19. Contact with liquid surface. Note that the seed crystal 17 is introduced into the pulling container 4 from the substrate entrance/exit 16 in advance. In FIG. 4, illustration of the melt 21 and the melt pool 22 is omitted in order to give priority to the visibility of the slit 19 and the opening 20.

FIG. 4 is a diagram showing the positional relationship between the seed crystal 17 and the partition plate 18. As described above, by making the planar direction of the seed crystal 17 orthogonal to the longitudinal direction of the partition plate 18, it is possible to reduce the contact area between the seed crystal 17 and the melt 21. Therefore, the contact portion of the seed crystal 17 becomes compatible with the melt 21, and crystal defects are less likely to occur in the grown ceramic composite 2.

When bringing the seed crystal 17 into contact with the melt surface, the lower part of the seed crystal 17 may be brought into contact with the upper part of the partition plate 18 and melted. FIG. 5(b) is a diagram showing how a part of the seed crystal 17 is melted. By melting a part of the seed crystal 17 in this way, the temperature difference between the seed crystal 17 and the melt 21 can be quickly eliminated, and the occurrence of crystal defects in the ceramic composite 2 can be further reduced. It becomes possible.

Subsequently, the substrate holder is pulled up at a predetermined lifting speed, and pulling of the seed crystal 17 is started. Specifically, the substrate holder is raised by the shaft 13 at a predetermined speed.

Incidentally, in order to more easily align the seed crystal with respect to the opening 20 of the die 9, an unevenness may be provided on the lower side of the seed crystal 17. FIG. 6 is a diagram illustrating the shape of the lower side of the seed crystal 17. FIG. 6(a) shows the case where the lower side is comb-shaped, and FIG. 6(b) shows the case where the lower side is saw-shaped.

The spacing between the concave and convex portions is adjusted to the spacing between the openings 20, and the convex portion is aligned with the center of the melt pool 22. By providing the convex portion, the convex portion can be used as a starting point for the growth of the ceramic composite 2, and the ceramic composite 2 can be formed more easily. Note that the shape of the unevenness is not limited to that shown in FIG. 6, and may be, for example, a wavy uneven shape.

The substrate holder is raised at a predetermined speed, and as shown in FIG. 7, the ceramic composite 2 is grown so as to be expanded in the longitudinal direction of the die 9 (spreading) with the seed crystal 17 at the center. When the ceramic composite 2 is expanded to the full width of the die 9 (the end of the partition plate 18) (full spread), a flat ceramic composite 2 with a wide area and a width comparable to the full width of the die 9 is grown. (direct body process). FIG. 7 is a schematic diagram showing how the width of the ceramic composite 2 is expanded by the spreading process. By obtaining a wide ceramic composite 2, the yield of ceramic composite products is improved.

After the ceramic composite 2 is grown to the full width of the die 9 through the spreading process, as shown in FIG. A pulling process is carried out in which the ceramic composite body 2 is pulled up to a predetermined length (straight body length) to obtain a flat plate-shaped ceramic composite body 2.

During the pulling process, the temperature is controlled using the heater 7 or the like so that the interface temperature of the melt 21 in the melt pool 22 formed above the slit 19 is constant. The ceramic composite 2 grows as the melt 21 that has risen to the melt pool 22 comes into contact with the seed crystal 17, the neck 25, and the straight body portion 26, and is cooled while being pulled up. Therefore, by controlling the temperature of the melt reservoir 22 to be constant, the crystal growth conditions can be kept the same during the growth period of the ceramic composite 2, and a uniform lamellar structure can be formed over the entire area of the ceramic composite 2. I can do it.

The pulling speed of the seed crystal 17 in the pulling step is preferably in the range of 0.9 mm/hour or more and 400 mm/hour or less. More preferably, it is in the range of 50 mm/hour or more and 200 mm/hour or less. By setting the pulling rate of the seed crystal 17 to 50 mm/hour or more, cracks can be prevented from being introduced into the ceramic composite 2. Furthermore, by setting the pulling speed to 200 mm/hour or less, the growth state of the ceramic composite 2 can be further stabilized.

When the pulling speed is less than 0.9 mm/hour, the size of the lamellar structure fluctuates greatly due to an error in the pulling speed, making it difficult to control the size of the lamellar structure. Therefore, the white light emission intensity of the grown ceramic composite 2 is reduced. In addition, productivity is low due to slow growth rate. If the pulling speed is higher than 400 mm/hour, it becomes difficult to control the temperature of the melt reservoir 22, and therefore it becomes difficult to control the size of the lamellar structure. On the other hand, if the pulling speed is too high, the melt 21 in the melt pool 22 will be separated from the seed crystal 17, the neck 25, and the straight body portion 26, which increases the possibility that the growth will be interrupted, which is not preferable.

Thereafter, the obtained ceramic composite body 2 is allowed to cool, the gate valve 15 is opened, and the ceramic composite body 2 is moved to the pulling container 4 side and taken out from the substrate entrance/exit port 16. The appearance of the obtained flat plate-shaped ceramic composite body 2 is shown in FIG. Although the straight body length is not particularly limited, it is preferably 2 inches or more (50.8 mm or more).

Alternatively, as shown in FIG. 14, the entire width of the die 9 and the width of the seed crystal 17 may be made the same, and the ceramic composite 2 may be grown with the same width as the entire width of the seed crystal 17. Note that in FIG. 14 as well, illustration of the melt 21 and the melt pool 22 is omitted in order to give priority to the visibility of the slit 19.

By using the manufacturing apparatus 1, seed crystal 17, and die 9 as described above, it is possible to simultaneously manufacture a plurality of ceramic composites 2 from a common seed crystal 17. Therefore, it is possible to reduce the manufacturing cost of each ceramic composite body 2.

Further, in the EFG method, a plurality of ceramic composites 2 are grown. Therefore, by uniformly cooling and cooling the plurality of ceramic composites 2, it is possible to obtain a uniform lamellar structure without variations.

Therefore, the die 9 including the seed crystal 17 and the partition plate 18 must be precisely positioned. Therefore, as shown in FIG. 1, the manufacturing apparatus 1 is provided with a crucible drive section 6 that rotates the crucible 5 in which the die 9 is installed, and a control section (not shown) that controls the rotation. Further, regarding the shaft 13, a shaft drive section 14 that rotates the shaft 13 and a control section (not shown) that controls the rotation thereof are provided. That is, the positioning of the seed crystal 17 with respect to the die 9 is adjusted by rotating the shaft 13 or the crucible 5 by the control section. Precise positioning of the seed crystal 17 and the die 9 can also be achieved by using a die 9 in which a portion of the slope 30 of each partition plate 18 is cut out.

FIG. 9 is a micrograph showing the surface of the ceramic composite 2 obtained by the above-mentioned EFG method. As shown in FIG. 9, in the ceramic composite 2 of this embodiment, a first phase of Y ₃ Al ₅ O ₁₂ phase and a second phase of Al ₂ O ₃ phase exist as eutectic. It has a lamellar structure in which the first phase and the second phase are three-dimensionally entangled with each other. In the figure, the region shown in dark color is the Y ₃ Al ₅ O ₁₂ phase, and the region shown in light color is the Al ₂ O ₃ phase. Further, the first phase and the second phase have few independent island-like separated regions, and have three-dimensionally continuous regions.

Further, the composition ratio of the Y ₃ Al ₅ O ₁₂ phase contained in the ceramic composite 2 is 19.72±2.00 mol %, which is near the eutectic composition. When the composition ratio of the Y ₃ Al ₅ O ₁₂ phase is out of this range, it is difficult to uniformly form a lamellar structure in eutectic form with the Al ₂ O ₃ phase.

Moreover, the content of Ce in the Y ₃ Al ₅ O ₁₂ phase is preferably in the range of 0.01 mol% or more and 5.0 mol% or less. If it is less than 0.01 mol%, the effective strength of the ceramic composite 2 will be weakened, making it unsuitable for use in lighting devices. On the other hand, if it exceeds 5.0 mol %, other compounds other than desired will be generated and will not contribute to the emission of white light. By partially replacing Y in the Y ₃ Al ₅ O ₁₂ phase with Ce, the Y ₃ Al ₅ O ₁₂ phase functions as a phosphor material, absorbing the blue light that is the primary light and converting it to the secondary light. Emit yellow light. The thermal conductivity of the Al ₂ O ₃ phase is approximately 4 times higher than that of the Y ₃ Al ₅ O ₁₂ phase, and is important for converting primary light in the Y ₃ Al ₅ O ₁₂ phase into secondary yellow light. Heat can be dissipated efficiently. In the Y ₃ Al ₅ O ₁₂ phase, the absorption wavelength and emission wavelength change depending on the Ce concentration, but the ceramic composite of this embodiment has a uniform fine lamellar structure even when the Ce content is relatively high, as will be described later. can be formed.

Furthermore, the ceramic composite 2 contains MgO in a range of 10 ppm or more and 500 ppm or less. By containing MgO in this range, the conversion efficiency from blue light to white light can be increased, and the emission intensity of white light can be increased.

In addition, in the ceramic composite 2 of this embodiment, in the lamellar structure of the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase, the average value of the lamella spacing in the Y ₃ Al ₅ O ₁₂ phase is 0.5 μm or more and 20 μm or less. It is preferable that Here, the lamella spacing of the Y ₃ Al ₅ O ₁₂ phase indicates the width of the Y ₃ Al ₅ O ₁₂ phase sandwiched between the Al ₂ O ₃ phases, and the width of the Y ₃ Al ₅ O ₁₂ phase in the longitudinal direction. It shows the width across. When the lamella spacing is less than 0.5 μm, the size of the Y ₃ Al ₅ O ₁₂ phase becomes several times the wavelength of blue light, making it difficult to uniformly convert the wavelength of blue light into yellow light. I end up. In addition, when the lamella interval is larger than 20 μm, the lamella structure is insufficiently dense, and the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase are separated while the blue light is transmitted through the ceramic composite 2. The number of times that light enters the interface decreases, and the light is not sufficiently scattered, resulting in a decrease in the efficiency of wavelength conversion and color mixing.

Furthermore, since the ceramic composite 2 is manufactured using the EFG method as described above, a small amount of molybdenum (Mo) or tungsten (W), which is the material of the crucible 5, is dissolved into the melt 21 and the ceramic composite is formed. Incorporated into 2. Therefore, the ceramic composite 2 contains a trace amount of Mo or W in addition to the above-mentioned Y ₃ Al ₅ O ₁₂ phase and Al ₂ O ₃ phase, MgO and Ce.

The amount of Mo or W contained in the ceramic composite 2 is preferably in the range of 1 mol·ppm to 30,000 mol·ppm, more preferably in the range of 100 mol·ppm to 3,000 mol·ppm. In manufacturing the ceramic composite 2 using the EFG method, it is impossible to completely prevent the material in the crucible 5 from dissolving into the melt 21, and the content of Mo or W is set to less than 1 mol ppm. That is extremely difficult. Moreover, if the content of Mo or W is increased to exceed 30,000 mol·ppm, the crystallinity of the Y ₃ Al ₅ O ₁ phase and the Al ₂ O ₃ phase deteriorates, which deteriorates the wavelength conversion efficiency, which is not preferable. By setting the content of Mo or W to 100 mol/ppm or more and 3000 mol/ppm or less, these problems are resolved, and the primary light and secondary light are uniformly scattered, making it possible to increase the amount of white light emitted. Therefore, it is the most desirable. Therefore, by setting the content of Mo or W contained in the ceramic composite 2 to at least 1 mol/ppm or more and 30,000 mol/ppm or less, a fine lamellar structure is formed and light is scattered uniformly, resulting in uniform emission intensity. It is possible to improve conversion efficiency and conversion efficiency.

When a material other than Mo or W is used as the crucible 5, the amount of the material in the crucible 5 dissolved into the melt 21 increases due to its low melting point, and the content of elements derived from the crucible 5 contained in the ceramic composite 2 increases. It is not desirable because Further, it is not preferable to use a material with a high melting point other than Mo or W as the material constituting the crucible 5 because of problems such as reactivity with the raw material melt 21 and moldability of the crucible 5. Therefore, in order to manufacture the ceramic composite 2 using the EFG method and refine the lamellar structure of the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase, the ceramic composite 2 must contain Mo or W in the above range. It is important that this is included.

The shape and size of the ceramic composite 2 are not limited, but from the viewpoint of preventing deterioration of workability of the ceramic composite 2, a rectangular shape with a width of 0.5 mm or more and 300 mm or less and a length of 10 mm or more and 1000 mm or less, or a diameter It is desirable that the diameter is 0.5 mm or more and 2 mm or less. As mentioned above, since the ceramic composite 2 of this embodiment is manufactured using the EFG method, it is possible to easily obtain a large-area ceramic composite 2 by increasing the width of the die 9 and the length of the die 9. It is. In addition, since it has a fine structure with an average value of lamella spacing ranging from 0.5 μm to 20 μm, light is easily scattered at the interface between the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase. Even if the area is large, it can scatter light uniformly over the entire surface, producing uniform white light.

Further, the thickness of the ceramic composite 2 is not limited, but is preferably in the range of 0.1 mm or more and 4.0 mm or less, more preferably 0.5 mm or more and 2.0 mm or less. If the thickness of the ceramic composite 2 is less than 0.1 mm, it becomes difficult to control the growth using the EFG method, and the influence of thickness due to manufacturing errors and in-plane thickness unevenness increases. It becomes difficult to obtain white light uniformly over the entire area. In addition, since the thermal conductivity of the Y ₃ Al ₅ O ₁₂ phase contained in the ceramic composite 2 is only about 1/4 of that of the Al ₂ O ₃ phase, thickening the crystal deteriorates heat dissipation, causing temperature drop on the surface and inside. Differences are more likely to occur. Therefore, if the thickness of the ceramic composite 2 is greater than 4.0 mm, a temperature difference between the outside and the inside in the thickness direction is likely to occur during pulling by the EFG method, a colony structure is likely to occur, and the lamella spacing is This is not preferred because uniformity is impaired.

Figures 10 to 12 are micrographs showing the lamellar structure when the pulling speed was varied in the EFG method. Figure 10 shows the case of pulling at a small speed, and Figure 11 shows the case of pulling at a medium speed. FIG. 12 shows the case of pulling at a high speed. The range shown in each photograph is a square with one side of 129 μm.
(Example 1)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol %, and the pulling rate was 0.035 inches/hour (approximately 0.9 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 26.6 μm.
(Example 2)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol%, and the pulling rate was 0.2 inches/hour (approximately 5 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 15.2 μm.
(Example 3)

The concentration of Ce contained in the ceramic composite 2 was 0.3 mol %, and the pulling rate was 1.0 inch/hour (about 25 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 6.0 μm.
(Example 4)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol%, and the pulling rate was 1.0 inch/hour (about 25 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 5.5 μm.
(Example 5)

The concentration of Ce contained in the ceramic composite 2 was 0.3 mol%, and the pulling rate was 2.0 inches/hour (approximately 50 mm/hour). The average lamella spacing of the phases was measured and was 3.5 μm.
(Example 6)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol %, and the pulling rate was 2.0 inches/hour (approximately 50 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 4.6 μm.
(Example 7)

The concentration of Ce contained in the ceramic composite 2 was 1.0 mol%, and the pulling rate was 2.0 inches/hour (approximately 50 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 5.1 μm.
(Example 8)

The concentration of Ce contained in the ceramic composite 2 was 0.3 mol %, and the pulling rate was 4.0 inches/hour (about 100 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured to be 2.6 μm.
(Example 9)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol %, and the pulling rate was 4.0 inches/hour (about 100 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 3.0 μm.
(Example 10)

The concentration of Ce contained in the ceramic composite 2 was 1.0 mol%, and the pulling rate was 4.0 inches/hour (about 100 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 4.4 μm.
(Example 11)

The concentration of Ce contained in the ceramic composite 2 was 0.5 mol %, and the pulling rate was 8.0 inches/hour (approximately 200 mm/hour). The average lamella spacing of the ₁₂ Y ₃ Al ₅ O phases was measured and was 4.4 μm.

When the ceramic composites 2 of Examples 1 to 11 with a thickness of 0.5 mm were irradiated with blue light with a wavelength of 450 nm, the blue light was scattered within the ceramic composites 2 and a portion of the blue light was scattered in each example. The wavelength of the light was converted into yellow light and the light irradiated to the outside was uniform white light.

As shown in FIGS. 10 to 12, in all of Examples 1 to 11, white light could be obtained by scattering and wavelength conversion of blue light. Furthermore, it was confirmed that by increasing the pulling speed of the ceramic composite 2 by the EFG method, the lamella spacing of the Y ₃ Al ₅ O ₁₂ phase tended to become smaller. Furthermore, it was confirmed that the refinement of the lamellar structure was maintained even when the Ce concentration was in the range of 0.01 mol% to 5.0 mol%. It can also be seen that the lower the Ce concentration, the smaller the lamella spacing.

FIG. 13 is a graph showing the relationship between the pulling speed and the lamella spacing in Examples 1, 2, 4, 6, 9, and 11 in which the Ce concentration is 0.5 mol%. In the graph shown in FIG. 13, the horizontal axis is the pulling speed (μm/sec), and the vertical axis is the lamella spacing (μm) of the Y ₃ Al ₅ O ₁₂ phase.

As shown in FIG. 13, in the method for manufacturing the ceramic composite 2 of this embodiment, the pulling speed V (μm) of the seed crystal 17 and the lamella spacing d (μm) of the Y ₃ Al ₅ O ₁₂ phase are d It can be seen that there is a relationship of =a·V ^?1/2 (a is a constant). In the example shown in FIG. 13, the constant a=about 13. a can be set to 9 to 18 depending on the lamella spacing d; the narrower d, the smaller a, and the wider d, the larger a. Therefore, by using the same equipment and growth conditions, it is possible to control the lamella spacing of the ceramic composite 2 obtained by simply controlling the pulling speed V, and it is possible to keep the lamella spacing d uniform for each pulling speed V. becomes possible

Furthermore, from FIG. 13, it can be seen that when the pulling speed is less than 0.9 mm/hour (approximately 0.25 μm/sec), the variation in the lamella spacing is extremely large. Therefore, if an error occurs in the pulling speed V, the size of the lamellar structure will vary greatly, making it difficult to control the size of the lamellar structure.

Further, in FIG. 13, although the pulling speed is plotted only up to 56 μm/sec, it is presumed that the above relational expression is satisfied even at a pulling speed higher than 56 μm/sec. The higher the pulling speed is, the smaller the lamella interval is, which is preferable because it can scatter light more uniformly. However, if it is higher than 500 mm/hour (approximately 140 μm/sec), the lamella interval becomes too small and approaches the wavelength of light, which can lead to This is not preferable because scattering becomes difficult to occur.

Further, if the pulling speed is higher than 400 mm/hour (approximately 110 μm/sec), it becomes difficult to control the temperature of the melt pool 22, and therefore it becomes difficult to control the size of the lamellar structure. On the other hand, if the pulling speed is too high, the melt 21 in the melt pool 22 will be separated from the seed crystal 17, the neck 25, and the straight body portion 26, which increases the possibility that the growth will be interrupted, which is not preferable.

As described above, in the method for manufacturing the ceramic composite 2 of the present embodiment, a plurality of dies 9 each having a slit 19 and arranged in parallel in the longitudinal direction are housed in the crucible 5. A step of charging raw materials containing at least aluminum oxide, yttrium oxide, magnesium oxide, and cerium oxide, a step of heating the crucible 5 and melting the raw materials in the crucible 5 to prepare a melt 21, and a step of preparing the melt 21 through the slit 19. forming a melt pool in which the melt 21 is stored above the slit 19 through the slit 19; bringing the seed crystal 17 into contact with the melt pool; and pulling the seed crystal 17 at a pulling rate of 0.9 mm/hour to 400 mm/hour; It has a lifting process. As a result, it is possible to control the lamella spacing between the Y ₃ Al ₅ O ₁₂ phase and the Al ₂ O ₃ phase, and it is possible to control the size of the lamellar structure that uniformly scatters the primary light and the wavelength-converted secondary light. It becomes possible. Therefore, the efficiency of wavelength conversion into secondary light can be improved. Furthermore, it is possible to maintain a uniform lamella interval for each pulling speed of the seed crystal 17.

Furthermore, in the present invention, by growing the ceramic composite 2 using the EFG method, the pulling speed of the seed crystal is varied within the range of 0.9 mm/hour to 400 mm/hour, and Ce is added to the ceramic composite 2. Even if it is contained, the occurrence of colony structure can be prevented. A colony structure is a structure in which a part of a lamellar structure where a plurality of phases with a short phase interval exist densely is surrounded by a part where a plurality of phases with a long phase interval exist sparsely. As shown in FIGS. 9 to 12, no such colony structure was observed to occur in this embodiment or example. Therefore, uneven emission of white light in the ceramic composite 2 can be prevented.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. are also included within the technical scope of the present invention.

1... Manufacturing device 2... Ceramic composite 3... Growth container 4... Pulling container 5... Crucible 6... Crucible drive unit 7... Heater 8... Electrode 9... Die 10... Heat insulating material 11... Atmospheric gas inlet 12... Exhaust port 13... Shaft 14...Shaft driving part 15...Gate valve 16...Substrate entrance/exit 17...Seed crystal 18...Partition plate 19...Slit 21...Melt 23...Notch part 24...Notch hole 26...Body part 30...Slope

Claims (2)

A plurality of dies each having a slit and arranged in parallel in the longitudinal direction are housed in a crucible made of molybdenum or tungsten , and raw materials containing at least aluminum oxide, yttrium oxide, magnesium oxide, and cerium oxide are placed in the crucible. The process of inputting
heating the crucible to melt the raw material in the crucible to prepare a melt;
forming a melt pool containing the melt above the slit through the slit;
A pulling step of bringing a seed crystal into contact with the melt pool and pulling the seed crystal at a pulling rate of 0.9 mm/hour or more and 400 mm/hour or less ,
The first phase, Y ₃ Al ₅ O ₁₂ phase, and the second phase, Al ₂ O ₃ phase, exist as a eutectic, and the first phase and the second phase are intertwined with each other in a lamellar structure. A method for producing a ceramic composite comprising pulling a ceramic composite having a molybdenum or tungsten content of 1 mol/ppm or more and 30,000 mol/ppm or less and a thickness of 0.1 mm or more and 4.0 mm or less. . 2. The method for manufacturing a ceramic composite according to claim 1, wherein the interface temperature of the melt in the melt pool is constant during the pulling process.

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