Ceramic composition and method for producing the same

Abstract

To provide an inexpensive material having a light-emitting function.SOLUTION: A ceramic composition consists of two phases of a corundum phase and a CeAl11O18 phase, and contains the CeAl11O18 phase in an amount of 0.5 mol% or more and 5 mol% or less. A producing method of the ceramic composition comprises the steps of: mixing cerium oxide powder and aluminum oxide powder; obtaining a compact by forming the material obtained by the mixing; and firing the obtained compact at a temperature of 1,400°C or more and 1,700°C or less in a reducing atmosphere.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ceramic composition and a method for making the ceramic composition. [Background technology]

[0002] Generally, for example, alumina ceramics containing 90 to 99.9 weight percent or more are used in semiconductor packaging components. Alumina ceramics are widely used in various industrial fields because they have excellent mechanical strength, thermal conductivity, and electrical insulation properties, and their manufacturing process is stable and inexpensive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-002488 [Patent Document 2] Special Publication No. 2016-519829 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-060179 [Patent Document 4] Special Publication No. 2008-533270 [Patent Document 5] Special Publication No. 2008-521238 [Patent Document 6] Special Publication No. 2003-500805 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a ceramic composition, such as an alumina ceramic, is required to have a luminescent function, a process such as coating with a fluorescent material is required, which increases the production cost of the ceramic composition. Adding a compound with fluorescent properties to the ceramic has also been considered, but this also increases the production cost of the ceramic composition because a compound made from a combination of various materials is added. Furthermore, if a large amount of compound is added, the advantages of the ceramic as a functional or structural part, such as mechanical strength and thermal conductivity, are impaired.

[0005] The disclosed technology has been made in consideration of these points, and aims to provide a ceramic composition that can provide an inexpensive material having luminescent properties, and a method for manufacturing the ceramic composition. [Means for solving the problem]

[0006] In one embodiment, the ceramic composition disclosed herein comprises a corundum phase and a CeAl 11 O 18 The CeAl phase is composed of two phases. 11 O 18 phase in an amount of 0.5 mole percent to 5 mole percent. [Effects of the Invention]

[0007] According to one aspect of the ceramic composition and the method for producing the ceramic composition disclosed in the present application, it is possible to provide an inexpensive material having a light-emitting function. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a flow diagram showing a method for producing a ceramic composition according to one embodiment. [Figure 2] FIG. 2 is a diagram showing the composition of a ceramic composition according to one embodiment. [Figure 3] FIG. 3 is a diagram showing the structure of a ceramic composition according to one embodiment. [Figure 4] FIG. 4 shows a specific example of luminescence of a ceramic composition. [Figure 5] FIG. 5 is a diagram showing specific examples of excitation wavelengths and emission wavelengths. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the ceramic composition and the method for manufacturing the ceramic composition disclosed in the present application will be described in detail with reference to the drawings. However, the present invention is not limited to this embodiment.

[0010] 1 is a flow diagram showing a method for producing a ceramic composition according to one embodiment. This ceramic composition is made from aluminum oxide and cerium, and emits photoluminescence light, which is electromagnetic waves in a wavelength range of, for example, 300 to 550 nm, in response to irradiation with electromagnetic waves in a wavelength range of, for example, 250 to 402 nm.

[0011] First, 1 mole percent of cerium oxide (CeO) powder with a purity of 99.9 weight percent is added to aluminum oxide powder with a purity of 99.99 weight percent and an average particle size of less than 1 μm. The amount of cerium oxide powder added can be 0.5 mole percent to 5 mole percent. Next, an organic binder component and a plasticizer component are added to these powders, and they are wet-mixed in an alcohol-based liquid medium (Step S101).

[0012] The slurry material obtained by wet mixing is molded into a predetermined shape such as a tape by, for example, a doctor blade method (step S102). Note that the shape of the molded body is not limited to a tape shape and may be any shape.

[0013] The compact is subjected to reduction firing in a nitrogen gas atmosphere containing hydrogen at a temperature of 1400°C or higher, preferably 1500°C to 1700°C, to obtain a sintered body (step S103). 11 O 18The ceramic composition contains the above-mentioned compound and has a luminescent function.

[0014] FIG. 2 shows the X-ray diffraction pattern of a powdered sample of the ceramic composition formed above.

[0015] As shown in Figure 2, the measured data from the sample consisted mostly of corundum phase, with CeAl due to the added cerium oxide. 11 O 18 phases, i.e., the ceramic composition contains a corundum phase and a CeAl 11 O 18 It can be seen that the sample consists of two phases. Note that tungsten carbide was also detected from the measurement data, but this is a foreign substance (contamination) resulting from the grinding media material used to obtain the sample.

[0016] Since the amount of cerium oxide added to the aluminum oxide is less than 5 mole percent, the corundum phase forms a continuous phase, which is the main constituent phase, and CeAl 11 O 18 The phases are present in a dispersed state. Specifically, a backscattered electron image of a polished surface of the ceramic composition is shown in FIG.

[0017] As shown in FIG. 3, the ceramic composition according to the present embodiment is composed of a corundum phase 110 forming a continuous phase shown in gray in the figure and a crystalline CeAl 2 O 3 shown in white in the figure. 11 O 18 phases 120a and 120b. 11 O 18 The crystals 120a and 120b of the CeAl phase are dispersed in the corundum phase 110. In FIG. 3, the crystals 120a are planar, whereas the crystals 120b are linear. 11 O 18 It is believed that the crystals 120a were observed from the front, whereas the crystals 120b were observed from the side, because the crystals have a flat plate-like shape. Note that, because the ceramic composition is produced by firing, the corundum phase 110 contains bubbles 130, shown in black in the figure.

[0018] Thus, the ceramic composition contains a continuous corundum phase and dispersed CeAl 11 O 18 Since the ceramic composition is composed of two phases, the alumina ceramic and the cerium oxide phase, it has mechanical strength, thermal conductivity, and electrical insulation properties equivalent to those of alumina ceramics, making it a material that can be used for a variety of functional or structural components. Furthermore, the method for producing this ceramic composition can also be applied to the production of ordinary alumina ceramics, except that cerium oxide is mixed in, and the production cost does not increase. In other words, the ceramic composition according to this embodiment can be produced inexpensively.

[0019] Fig. 4 shows a specific example of light emission from the ceramic composition according to the present embodiment, in which a normal alumina ceramic 210 and a cerium-added ceramic composition 220 are irradiated with ultraviolet light having a wavelength of 254 nm.

[0020] As shown in Figure 4, when exposed to ultraviolet light, a typical alumina ceramic 210 does not emit light, whereas the ceramic composition 220 according to this embodiment emits strong light. As described above, the ceramic composition 220 according to this embodiment contains 0.5 mol percent or more of cerium oxide, and therefore can achieve sufficient excitation luminescence intensity. When the excitation wavelength of the ultraviolet light irradiated on the ceramic composition 220 is 254 nm, the emitted light color is, for example, bluish-white. This emitted light color changes with changes in the excitation wavelength.

[0021] Fig. 5 is a diagram showing a specific example of the relationship between excitation wavelength and emission wavelength. Fig. 5 shows an emission spectrum when the excitation wavelength of the electromagnetic wave irradiated to the ceramic composition according to this embodiment is 306 to 402 nm. However, the ceramic composition according to this embodiment emits light in the emission wavelength range of 300 to 550 nm as long as the excitation wavelength is at least 250 nm or more.

[0022] As shown in Figure 5, in the excitation wavelength range of 306 to 322 nm, as the excitation wavelength increases, the peak emission wavelength gradually shifts from approximately 440 nm to the shorter wavelength side, and the peak intensity decreases. Furthermore, when the excitation wavelength is 314 nm or shorter, emission with an emission wavelength of approximately 350 nm is observed. That is, when the excitation wavelength is 314 nm or shorter, the shortest emission wavelength is approximately 350 nm, and emission with this emission wavelength disappears when the excitation wavelength is 322 nm or longer.

[0023] On the other hand, in the excitation wavelength range of 330 nm or more, as the excitation wavelength increases, the peak emission wavelength gradually shifts from approximately 440 nm to approximately 480 nm, and the peak intensity decreases slightly. At excitation wavelengths of 322 nm or more, the emission at approximately 350 nm disappears, and the shortest emission wavelength becomes equal to the peak emission wavelength. Therefore, in the excitation wavelength range of 314 nm or more, the shortest emission wavelength increases from 350 nm as the excitation wavelength increases.

[0024] CeAl contained in the ceramic composition according to this embodiment 11 O 18 Although it has a distorted magnetoplumbite-type structure, it is thought that partial substitutions and defects exist due to its non-stoichiometric composition. CeAl 11 O 18 As a result of this effect, it is thought that the emission wavelength also changes with the change in excitation wavelength.

[0025] In this way, since the emission wavelength and the emission intensity change when the excitation wavelength changes, the emission color of the ceramic composition can be changed by irradiating it with electromagnetic waves of different wavelengths. In other words, the emission color of the ceramic composition makes it possible to identify the wavelength of the electromagnetic waves irradiated onto the ceramic composition.

[0026] As described above, according to this embodiment, the corundum phase forming the continuous phase and the CeAl phase dispersed in the continuous phase can be obtained by a simple process. 11 O18 This results in a ceramic composition consisting of two phases: alumina and SiO2. This allows for the production of a material that has the same mechanical strength, thermal conductivity, and electrical insulation as alumina ceramics, while also having luminescent properties. In other words, it is possible to provide an inexpensive material that has luminescent properties. [Explanation of symbols]

[0027] 110 Corundum phase 120a, 120b CeAl 11 O 18 phase 130 bubbles

Claims

1. Corundum phase and CeAl 11 O 18 The CeAl phase is composed of two phases. 11 O 18 phase containing 0.5 mol percent to 5 mol percent A ceramic composition characterized by:

2. It is excited by electromagnetic waves having a wavelength of at least 250 nm or more and 402 nm or less, and the wavelength at which the emission spectrum peaks is in the range of 300 nm or more and 550 nm or less, and When excited by electromagnetic waves with wavelengths of 314 nm or more, the shortest emission wavelength increases with increasing excitation wavelength. The ceramic composition of claim 1.

3. The corundum phase forms a continuous phase, The CeAl 11 O 18 The phase is dispersed in the continuous phase 3. The ceramic composition according to claim 1 or 2.

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