Yttrium aluminum garnet sintered body and method for producing the same

Abstract

Provided is a YAG sintered body that exhibits high transparency and can be produced by a short oxygen annealing treatment time. The glass contains silicon and a Group 2 element, and has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to the added element). -1 1. A yttrium aluminum garnet sintered body, characterized in that:

Description

[Technical Field]

[0001] The present invention relates to an yttrium aluminum garnet sintered body and a method for producing the same. [Background technology]

[0002] Conventionally, yttrium aluminum garnet (hereinafter also referred to as "YAG") sintered bodies have been used as laser oscillation elements. Laser beams are used for various purposes, such as medical scalpels and processing of materials such as metals, and YAG sintered bodies are required to function as high-power laser media. Such YAG sintered bodies are required to have high transparency.

[0003] As a transparent YAG sintered body, the optical loss coefficient when transmitting light with a wavelength of 300 to 1500 nm is 0.002 cm -1 The following polycrystalline YAG sintered body has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6502595 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, to obtain a transparent YAG sintered body, silicon is added as a sintering aid and high-temperature, high-pressure treatment in an inert atmosphere (hereinafter referred to as "HIP treatment") is required. However, in the case of a YAG sintered body to which only silicon is added, the originally trivalent Al 3+ A part of it is tetravalent silicon (Si 4+ ), so when HIP treatment is performed, the Y in the YAG sintered body 3+ is reduced to Y 2+This causes a problem of coloring of the YAG sintered body and a decrease in light transmittance. Such a YAG sintered body cannot be used as a high-power laser medium. Therefore, the YAG sintered body after HIP treatment must be heat-treated in an oxygen-containing atmosphere (hereinafter also referred to as "oxygen annealing") to eliminate the coloring. However, with thick YAG sintered bodies, the problem arises that oxygen annealing takes a long time.

[0006] In view of the above circumstances, the present invention aims to provide a YAG sintered body that exhibits high transparency and can be produced by a short oxygen annealing treatment time. Another object of the present invention is to provide a manufacturing method that can produce a YAG sintered body that exhibits high transparency and requires a short oxygen annealing treatment time. [Means for solving the problem]

[0007] As a result of extensive research, the inventors have discovered that by simultaneously adding silicon and a Group 2 element as sintering aids to a YAG sintered body, the oxygen annealing time required to eliminate the coloration of the sintered body after HIP processing can be significantly shortened, and a highly transparent YAG sintered body can be obtained.

[0008] That is, the present invention relates to the following YAG sintered body and a method for producing the same. 1. Contains silicon and Group 2 elements, and has a light loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to added elements). -1 1. A yttrium aluminum garnet sintered body, characterized in that: 2. The yttrium aluminum garnet sintered body according to Item 1, wherein the Group 2 element includes magnesium and / or calcium. 3. The yttrium aluminum garnet sintered body according to Item 2, wherein the molar ratio of the total number of moles of the magnesium and the calcium to the number of moles of the silicon ((Mg+Ca) / Si) is 15 or less. 4. The yttrium aluminum garnet sintered body according to any one of items 1 to 3, having an average crystal grain size of less than 5 μm. 5. The optical loss coefficient for light with a wavelength of 633 nm is 0.002 cm -1 5. The yttrium aluminum garnet sintered body according to any one of Items 1 to 4, which is as follows: 6. The optical loss coefficient for light with a wavelength of 1064 nm is 0.002 cm -1 6. The yttrium aluminum garnet sintered body according to any one of Items 1 to 5, which is as follows: 7. A method for producing a sintered yttrium aluminum garnet body, comprising: (1) Step 1: preparing a slurry containing yttrium aluminum garnet powder and a sintering aid, and hardening the slurry to produce a green body; (2) Step 2 of firing the molded body; (3) a step 3 of subjecting the fired compact to high temperature and high pressure treatment in an inert atmosphere; and (4) A step 4 of subjecting the high-temperature and high-pressure treated compact to an oxygen annealing treatment to produce a sintered compact, the sintering aid comprises a silicon-containing compound and a Group 2 element-containing compound; The sintered body has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to additive elements). -1 Below is the A manufacturing method characterized by: 8. The method of producing according to item 7, wherein the silicon-containing compound comprises SiO2. 9. The method according to item 7 or 8, wherein the Group 2 element-containing compound includes a magnesium-containing compound and / or a calcium-containing compound. 10. The manufacturing method according to item 9, wherein the molar ratio of the total number of moles of magnesium and calcium to the number of moles of silicon in the sintering aid ((Mg+Ca) / Si) is 15 or less. [Effects of the Invention]

[0009] The YAG sintered body of the present invention exhibits high transparency and can be produced by a short oxygen annealing treatment time. Furthermore, the method for producing a YAG sintered body of the present invention can produce a YAG sintered body that exhibits high transparency and requires a short oxygen annealing treatment time. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The following description of the components may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0011] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "to" means a numerical range that includes the numbers before and after "to" as the upper and lower limits.

[0012] In this specification, the expressions "contain" and "comprise" include the concepts of "contain," "include," "consist essentially of," and "consist only of."

[0013] 1. YAG sintered body The YAG sintered body of the present invention contains silicon and a Group 2 element, and has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to the added element). -1 The YAG sintered body of the present invention having the above characteristics contains silicon and a group 2 element at the same time, thereby achieving a charge balance throughout the sintered body and eliminating Y in the YAG sintered body, which is the cause of coloration after HIP treatment. 2+ The generation of oxygen annealing can be suppressed and the time required for oxygen annealing can be shortened.

[0014] The YAG sintered body of the present invention (hereinafter also simply referred to as "sintered body") will be described in detail below.

[0015] The sintered body of the present invention contains silicon and a Group 2 element as sintering aids. In the sintered body of the present invention, the silicon and the Group 2 element are silicon derived from a silicon-containing compound and a Group 2 element derived from a Group 2 element compound, respectively, in the method for producing a sintered body of the present invention described below.

[0016] The Group 2 element is not particularly limited, and known Group 2 elements can be used. Specific examples of Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra. Among these, Mg and Ca are preferred, and Ca is more preferred, from the viewpoint of further improving the transparency of the sintered body.

[0017] The above Group 2 elements can be used alone or in combination of two or more.

[0018] In the YAG sintered compact of the present invention, the Y element constituting the YAG sintered compact may be replaced by a rare earth element ranging from Ce (atomic number 57) to Yb (atomic number 70) to form a solid solution, or the Al element constituting the YAG sintered compact may be replaced by a transition metal element ranging from Ti (atomic number 22) to Ni (atomic number 28) to form a solid solution. In this specification, these elements are referred to as "additive elements." Of course, the YAG sintered compact of the present invention may be YAG itself without any additives.

[0019] The molar ratio of the total number of moles of magnesium and calcium to the number of moles of silicon in the sintered body ((Mg+Ca) / Si) is preferably 15 or less, more preferably 10 or less, even more preferably 7.5 or less, particularly preferably 5 or less, and most preferably 3 or less. By setting the upper limit of the molar ratio within the above range, the oxygen annealing treatment time can be shortened without impairing transparency compared to a sintered body containing only silicon. Furthermore, the lower limit of the molar ratio is not particularly limited and may be 0, 0.1, 0.2, 0.3, 0.5, etc.

[0020] The total content of silicon and Group 2 elements in the sintered body is not particularly limited as long as the sintered body exhibits high transparency, and can be adjusted appropriately.

[0021] In this specification, the content of silicon and group 2 elements in the sintered body can be measured by crushing the sintered body, dissolving it in a strong acid aqueous solution, and measuring it by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0022] The sintered body of the present invention has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm. -1 The light loss coefficient is 0.002 cm or less. -1 If the optical loss coefficient exceeds 0.0015 cm, the transparency of the sintered body becomes insufficient. -1 Less than 0.001cm is preferable -1 The lower limit of the optical loss coefficient is not particularly limited, and is preferably 0 cm or less. -1 , 0.0001cm -1 , 0.0002cm -1 , 0.0003cm -1 , 0.0005cm -1 etc. may also be used.

[0023] In the present invention, the optical loss coefficient is measured excluding wavelengths where there is absorption by the additive element in the sintered body of the present invention. For example, when no additive element is introduced, the optical loss coefficient is measured in the wavelength range of 300 to 2500 nm. Furthermore, when, for example, Nd is added, there is absorption of light by the additive element in the wavelength range of 300 to 1000 nm, so the optical loss coefficient is measured at wavelengths other than that, for example, at a wavelength of 1064 nm. If the optical loss coefficient measured at these wavelengths is 0.002 cm -1 The following is fine.

[0024] If the sintered body becomes opaque due to uneven sintering or other reasons, the optical loss coefficient will decrease over the entire measurement wavelength range (300 to 2500 nm), so there will be no particular problems even if the optical loss coefficient for the wavelength range where light is absorbed by the added element is excluded, as described above. Note that the wavelength of light absorbed by the added element can be determined in advance, for example, by producing or procuring a YAG single crystal into which the added element has been introduced and measuring its absorption spectrum.

[0025] The light loss coefficient in the present invention is calculated by the following formula using the light transmittance at each wavelength measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.). [Optical loss coefficient (% / cm)]=(-1 / L)×ln(T / T0) Here, L is the distance (cm) of the light passing through the measurement sample, and T is the light The transmittance, T0, is the light transmittance of a 0.2 mm thick YAG sintered substrate containing no added elements. The parallelism (deviation from perfectly parallelism) of both end faces of each sample is set to 30 seconds or less, and the flatness is set to λ / 10 or less (λ is the measurement wavelength) and the surface roughness (Ra) is set to 0.5 nm or less by polishing. However, in measuring the optical loss coefficient, wavelengths that are absorbed by added elements are excluded.

[0026] In the sintered body of the present invention, the average crystal grain size is preferably less than 5 μm, more preferably 3 μm or less. The average crystal grain size is preferably 1.0 μm or more, more preferably 1.5 μm or more. By setting the upper limit of the average crystal grain size within the above range, the annealing time of the sintered body can be shortened. Furthermore, by setting the lower limit of the average crystal grain size within the above range, the transparency of the sintered body can be further improved.

[0027] average crystal grain The diameter (μm) can be determined by the following measurement method using the following formula: crystal Particle size (μm)=1.56×L / (N-1) The surface of the obtained sintered body is flattened with a surface grinder and then mirror-polished. The mirror-polished sample is then heat-treated, for example, in air, at 1400-1500°C for 1 hour to cause intergranular corrosion. A surface photograph of this sample is taken with an SEM or optical microscope, and five straight lines are drawn randomly on the photograph. The number of grain boundaries present on each line is defined as N, and the distance of the lines calculated from the magnification and scale of the surface photograph is defined as L (μm). The average of the five calculated values ​​is defined as the average crystallinity. grain This is the measured diameter.

[0028] 2. Manufacturing method of YAG sintered body The method for producing the YAG sintered body of the present invention is as follows: (1) Step 1: preparing a slurry containing YAG powder and a sintering aid, and curing the slurry to prepare a green body; (2) Step 2 of firing the molded body; (3) a step 3 of subjecting the fired compact to high temperature and high pressure treatment in an inert atmosphere; and (4) A step 4 of subjecting the high-temperature and high-pressure treated compact to an oxygen annealing treatment to produce a sintered compact, the sintering aid comprises a silicon-containing compound and a Group 2 element-containing compound; The sintered body has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to additive elements). -1 The manufacturing method of the present invention is characterized by the following: Each step of the manufacturing method of the present invention will be described in detail below.

[0029] (Process 1) Step 1 is a step of preparing a slurry containing YAG powder and a sintering aid, and hardening the slurry to produce a compact.

[0030] The YAG powder is not particularly limited, and can be obtained by dropping a mixed solution containing an yttrium-containing compound and an aluminum-containing compound into an aqueous solution containing an ammonium salt, causing the reaction, and then firing the resulting amorphous precipitate. Alternatively, a commercially available YAG powder can be used. Alternatively, a mixed powder of aluminum oxide and yttrium oxide powders weighed to achieve the YAG composition can be used.

[0031] The sintering aids used in step 1 include silicon-containing compounds and Group 2 element-containing compounds. The silicon and Group 2 elements added as sintering aids exist as tetravalent and divalent cations, respectively, in the YAG sintered body. In the case of a YAG sintered body containing only silicon as a sintering aid, the Y in the YAG is converted into silicon by the HIP treatment in step 3 described below. 3+ A portion of the YAG is reduced to zero the overall charge, 2+ The Y 2+ is the cause of coloration of the YAG sintered body, but in the manufacturing method of the present invention, for example, Si 4+ and Ca 2+ By containing divalent cations derived from Group 2 element compounds such as Y 2+ This suppresses the generation of oxidative stress and reduces the coloring of the YAG sintered body produced. This makes it possible to shorten the oxygen annealing time required to eliminate the coloring of the YAG sintered body after HIP treatment.

[0032] The silicon-containing compound is not particularly limited as long as it contains silicon, and any known silicon-containing compound can be used. Examples of such silicon-containing compounds include SiO2 and TEOS (tetraethoxysilane, Si(OC2H5)4), and among these, SiO2 is preferably used.

[0033] The Group 2 element-containing compound is not particularly limited as long as it contains a Group 2 element. Specific examples of Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra. Among these, Mg and Ca are preferred from the viewpoints of shortening the annealing treatment time of the sintered body and further improving the transparency of the sintered body.

[0034] As the Group 2 element-containing compound, magnesium-containing compounds and calcium-containing compounds are preferred, and calcium-containing compounds are more preferred. Furthermore, examples of the Group 2 element-containing compound include oxides, chlorides, fluorides, carbonates, etc. of the above Group 2 elements, and among these, oxides and carbonates are preferably used. Specific examples of the Group 2 element-containing compound include magnesium oxide, calcium oxide, magnesium chloride, calcium chloride, magnesium carbonate, calcium carbonate, etc. Among these, magnesium oxide and calcium carbonate are preferred, and calcium carbonate is more preferred, from the viewpoints of being able to further shorten the annealing treatment time of the sintered body and further improving the transparency of the sintered body.

[0035] The molar ratio ((Mg+Ca) / Si) of the total number of moles of magnesium and calcium to the number of moles of silicon in the sintered body used in step 1 is preferably 15 or less, more preferably 10 or less, even more preferably 7.5 or less, particularly preferably 5 or less, and most preferably 3 or less. When the upper limit of the molar ratio is within the above range, the annealing treatment time of the sintered body can be shortened and the transparency of the sintered body can be further improved. In addition, the lower limit of the molar ratio is not particularly limited and may be 0, 0.1, 0.2, 0.3, 0.5, etc.

[0036] The slurry used in step 1 may contain a surfactant. Such surfactant is not particularly limited, and any known polymer compound used as a surfactant can be used.

[0037] Examples of the surfactant include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. The surfactants can be used alone or in combination of two or more.

[0038] The slurry used in step 1 may contain water and / or alcohol as a dispersion medium. The alcohol is not particularly limited as long as it can disperse the YAG powder and the sintering aid, and any known alcohol can be used.

[0039] The alcohol may, for example, be an alcohol having 1 to 10 carbon atoms. The number of carbon atoms in the alcohol is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. Specifically, methanol and ethanol are preferably used as such alcohols.

[0040] In step 1, a slurry containing the YAG powder and a sintering aid is prepared and hardened to produce a molded body. The method for hardening the slurry is not particularly limited. For example, the slurry is poured into a plaster mold and hardened under a pressure of about 490 kPa (about 5 kgf / cm). 2 ) pressure and molding.

[0041] The compact formed as described above may be degreased in step 1. The degreasing method is not particularly limited, and may involve heating at a temperature of 400 to 800°C, for example.

[0042] By the above-described step 1, the slurry containing the YAG powder and the sintering aid is hardened to prepare a compact.

[0043] (Process 2) Step 2 is a step of firing the molded body. The firing method is not particularly limited, and firing can be performed by a known method such as leaving the molded body in a high-temperature electric furnace for a certain period of time.

[0044] The firing temperature may be adjusted as appropriate, and is, for example, preferably from 1000 to 1800°C, more preferably from 1300 to 1750°C, and even more preferably from 1500 to 1700°C.

[0045] The firing time may be appropriately set depending on the firing temperature and the like, and is, for example, preferably 1 to 10 hours, more preferably 1.5 to 7 hours, and even more preferably 2 to 5 hours.

[0046] In step 2, the firing is preferably carried out under vacuum conditions. By carrying out vacuum firing, transparency is further improved.

[0047] In step 2 described above, the molded body prepared in step 1 is fired.

[0048] (Step 3) In step 3, the sintered compact is subjected to high-temperature and high-pressure treatment in an inert atmosphere. This is known as HIP (Hot Isostatic Pressing). Step 3 improves the transparency, mechanical impact resistance, and thermal impact resistance of the YAG sintered compact produced.

[0049] In step 3, HIP treatment is performed under an inert atmosphere, and the Y in the YAG containing only silicon derived from the sintering aid is removed. 3+ A part of the YAG is reduced to make the total charge zero, 2+ The Y 2+ However, in the manufacturing method of the present invention, by performing oxygen annealing in step 4 described later, Y 2+ Oxygen ions that cancel out the charge of YAG are supplied to the YAG sintered body. 2+ The charge of the YAG becomes zero and the color disappears, allowing the YAG sintered body to exhibit high transparency.

[0050] In step 3, the firing is carried out in an inert atmosphere. The inert atmosphere is not particularly limited and may be appropriately selected, for example, a nitrogen atmosphere, an argon atmosphere, etc. Among these, an argon atmosphere is more preferable.

[0051] The treatment temperature may be adjusted as appropriate, and is preferably 1350 to 1850°C, for example.

[0052] The treatment pressure may be adjusted as appropriate, and is preferably, for example, 50 to 200 MPa.

[0053] The treatment time may be appropriately set depending on the firing temperature and the like, and is preferably, for example, 1 to 30 hours.

[0054] In step 3 described above, the fired compact is subjected to high-temperature and high-pressure treatment in an inert atmosphere.

[0055] (Step 4) In step 4, the high-temperature, high-pressure treated compact is oxygen annealed to produce a sintered compact. Oxygen annealing is a heat treatment process in an oxygen-containing atmosphere, either in the air or under a certain pressure. By subjecting the compact to oxygen annealing, the coloring of the sintered compact is eliminated.

[0056] By carrying out the oxygen annealing treatment in step 4, it is possible to make the YAG sintered body, which has been colored by the HIP treatment in step 3, transparent. 2+ However, by performing oxygen annealing in step 4, Y 2+ Oxygen ions that cancel out the electric charge are supplied to the YAG sintered body, eliminating the coloring of the YAG sintered body.

[0057] The oxygen annealing temperature may be adjusted appropriately, and is preferably 1000 to 1500°C, for example.

[0058] The pressure during oxygen annealing may be adjusted appropriately, and is preferably, for example, atmospheric pressure to 200 MPa.

[0059] The oxygen annealing time may be adjusted as appropriate, and the treatment can be carried out for any time until the coloring of the YAG sintered body disappears.

[0060] By the above-described step 4, the compact that has been subjected to high temperature and high pressure treatment is subjected to oxygen annealing treatment, and a sintered body can be produced.

[0061] The YAG sintered body manufactured by the manufacturing method of the present invention has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to additive elements). -1 or less, and even if the thickness of the sintered body is thick, the time required for the coloring to be eliminated by oxygen annealing treatment (oxygen annealing time) is shortened. Such a YAG sintered body of the present invention can be usefully used as a laser oscillation element. The YAG sintered body of the present invention can be usefully used as a high-power laser oscillation element for various applications such as medical scalpels and processing of materials such as metals. [Example]

[0062] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0063] Example 1 A 0.5 mol / L yttrium nitrate solution and a 0.5 mol / L aluminum nitrate solution were weighed to a molar ratio of yttrium to aluminum of 3:5 and mixed in a reaction vessel to produce a YAG-composition mixed solution. This solution was added dropwise at a rate of 28 mL / min to a 2 mol / L ammonium bicarbonate solution adjusted to pH 8.0 with aqueous ammonia. Both the YAG-composition mixed solution and the ammonium bicarbonate solution were maintained at 25°C in a thermostatic bath. The pH reached a minimum of 7.0 during the addition and reached a constant value of 8.0 approximately 3 hours after the addition. After the addition, the mixture was aged for 24 hours at 25°C, and then filtered and washed four times. Repeated filtration and washing reduced the impurity anions in the precipitate, nitrate ions and free carbonate ions, to less than 2000 wtppm. The precipitate after washing was amorphous, but granular and easy to filter and wash with water, and its composition was carbonate or basic carbonate.

[0064] This amorphous precipitate was dried in air at 120°C and then calcined in air at 1300°C for 3 hours to produce a highly dispersible YAG powder with an average particle size of 0.1 μm for primary particles and 0.18 μm for secondary particles.

[0065] 75 g of the prepared YAG raw material powder, 50 g of ethanol, 1 g of Floren G-7000 (Kyoeisha Chemical Co., Ltd.) as a dispersant, nylon balls, and SiO2, a silicon-containing compound, were added to a nylon pot for ball milling. The amount of sintering aid added was 80 wtppm in terms of metal relative to the YAG powder. The mixture was then mixed for approximately 20 hours. The resulting slurry was defoamed in a vacuum defoamer for approximately 30 minutes and poured into a plaster mold at approximately 490 kPa (approximately 5 kgf / cm). 2 The resulting compact was thoroughly dried at room temperature and degreased at 750°C for 100 hours in air (Step 1).

[0066] Next, the compact was vacuum-sintered at 1650°C for 3 hours (step 2).

[0067] The fired compact was subjected to high-temperature and high-pressure treatment under conditions of a temperature of 1720°C and a pressure of 147 MPa in an inert atmosphere (argon) (step 3).

[0068] The high-temperature, high-pressure treated compact was then oxygen annealed in air at 1200°C for 100 hours to produce a sintered compact (Step 4). The molar ratio of calcium atoms to silicon atoms (Ca / Si) of the produced sintered compact was 0, as calcium was not used as a sintering aid.

[0069] (Examples 2 to 8, Comparative Examples 1 and 2) Sintered bodies were produced in the same manner as in Example 1, except that SiO2, a silicon-containing compound, and calcium carbonate, a Group 2 element, were added as sintering aids to change the molar ratio of calcium atoms to silicon atoms (Ca / Si) of the sintered body as shown in Table 1, and the oxygen annealing time was adjusted as shown in Table 1.

[0070] (Evaluation method) The following evaluations were carried out for the Examples and Comparative Examples.

[0071] Molar ratio of calcium atoms to silicon atoms in sintered body (Ca / Si) The molar ratio of calcium atoms to silicon atoms (Ca / Si) of the sintered body was measured by the following method: the YAG sintered body was finely pulverized, dissolved in a strong acid solution, and measured by ICP atomic emission spectroscopy (ICP-AES).

[0072] Light Loss Coefficient The optical loss coefficient when light with wavelengths of 300 to 2500 nm was transmitted through the sintered body was measured by the following method: That is, the optical transmittance at each wavelength was measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.) and calculated using the following formula. [Optical loss coefficient (% / cm)]=(-1 / L)×ln(T / T0) Here, L is the distance (cm) of the light passing through the measurement sample, and T is the light The transmittance, T0, is the light transmittance of a 0.2 mm thick YAG sintered substrate containing no added elements. The parallelism (deviation from perfectly parallel) of both end faces of each sample was set to 30 seconds or less, and the flatness was set to λ / 10 or less (λ is the measurement wavelength) and the surface roughness (Ra) to 0.5 nm or less by polishing. However, in measuring the optical loss coefficient, wavelengths that are absorbed by added elements were excluded.

[0073] transparency The sintered body was visually observed and the transparency was evaluated according to the following evaluation criteria. ◯: No colored portion of the sintered body was present. ×: Colored parts were present in the sintered body.

[0074] The results are shown in Table 1.

[0075] [Table 1]

Claims

1. It contains silicon and a Group 2 element, and has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths where absorption occurs due to the added element). －１ 1. A yttrium aluminum garnet sintered body, characterized in that:

2. 2. The yttrium aluminum garnet sintered body according to claim 1, wherein the Group 2 element includes magnesium and / or calcium.

3. 3. The yttrium aluminum garnet sintered body according to claim 2, wherein a molar ratio ((Mg+Ca) / Si) of the total number of moles of said magnesium and said calcium to the number of moles of said silicon is 15 or less.

4. 2. The yttrium aluminum garnet sintered body according to claim 1, wherein the average crystal grain size is less than 5 μm.

5. The optical loss coefficient for light with a wavelength of 633 nm is 0.002 cm －１ 2. The yttrium aluminum garnet sintered body according to claim 1, wherein:

6. The optical loss coefficient for light with a wavelength of 1064 nm is 0.002 cm －１ 2. The yttrium aluminum garnet sintered body according to claim 1, wherein:

7. A method for producing a sintered yttrium aluminum garnet body, comprising: (1) Step 1: preparing a slurry containing yttrium aluminum garnet powder and a sintering aid, and hardening the slurry to produce a green body; (2) Step 2 of firing the molded body; (3) a step 3 of subjecting the fired compact to high-temperature and high-pressure treatment in an inert atmosphere; and (4) a step 4 of subjecting the high-temperature and high-pressure treated compact to an oxygen annealing treatment to produce a sintered compact, the sintering aid comprises a silicon-containing compound and a Group 2 element-containing compound; The sintered body has an optical loss coefficient of 0.002 cm when transmitting light with a wavelength of 300 to 2500 nm (excluding wavelengths that are absorbed by additive elements). －１ Below is the A manufacturing method characterized by:

8. The silicon-containing compound is SiO ２ The method of claim 7, comprising:

9. The method of claim 7 , wherein the Group 2 element-containing compound comprises a magnesium-containing compound and / or a calcium-containing compound.

10. 10. The manufacturing method according to claim 9, wherein the molar ratio ((Mg+Ca) / Si) of the total number of moles of magnesium and calcium to the number of moles of silicon in the sintering aid is 15 or less.

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