WO2024135132A1 - Céramique transparente de type grenat paramagnétique, matériau magnéto-optique et dispositif magnéto-optique - Google Patents

Céramique transparente de type grenat paramagnétique, matériau magnéto-optique et dispositif magnéto-optique Download PDF

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WO2024135132A1
WO2024135132A1 PCT/JP2023/040097 JP2023040097W WO2024135132A1 WO 2024135132 A1 WO2024135132 A1 WO 2024135132A1 JP 2023040097 W JP2023040097 W JP 2023040097W WO 2024135132 A1 WO2024135132 A1 WO 2024135132A1
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garnet
type transparent
transparent ceramic
optical
sintering
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祐紀 片岡
恵多 田中
新二 牧川
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信越化学工業株式会社
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  • the present invention relates to paramagnetic garnet-type transparent ceramics, magneto-optical materials, and magneto-optical devices, and more specifically to paramagnetic garnet-type transparent ceramics that are translucent in the visible and/or near-infrared range, magneto-optical materials made of the above paramagnetic garnet-type transparent ceramics that are suitable for forming magneto-optical devices such as optical isolators, and magneto-optical devices using the same.
  • TGG crystals terbium gallium garnet crystals
  • JP 2011-213552 A Patent Document 1
  • the magnitude of the Faraday effect is quantified by the Verdet constant, and the Verdet constant for TGG crystals is 40 rad/(T ⁇ m) (0.13 min/(Oe ⁇ cm)) and for terbium-doped glass it is 0.098 min/(Oe ⁇ cm).
  • the Verdet constant of TGG crystals is relatively large, they are widely used as standard Faraday rotators.
  • TAG crystal terbium aluminum garnet crystal
  • the Verdet constant of TAG crystal is about 1.3 times that of TGG crystal, so the length of the Faraday rotator can be shortened, making it a good crystal that can be used in fiber lasers (for example, JP 2002-293693 A (Patent Document 2), JP 2004-539464 A (Patent Document 3)).
  • Patent Document 4 International Publication No. 2017/033618 (Patent Document 4) and “High Verdet constant of Ti-doped terbium aluminum garnet (TAG) ceramics” (Non-Patent Document 1)).
  • TAG ceramics and YTAG ceramics are said to be suitable for high power applications because they have a small thermal lens effect compared to TGG single crystals.
  • the thermal lens effect is a phenomenon in which a Faraday element absorbs transmitted light and generates heat, causing a change in refractive index and becoming lens-like. If the focal position of a laser processing machine moves due to the thermal lens effect, the beam becomes defocused at the processing point, which is undesirable because it reduces the processing accuracy. Therefore, attempts are being made daily to minimize the thermal lens effect of the Faraday element. In order to reduce this thermal lens effect, it is necessary to reduce the absorption coefficient and increase the thermal conductivity.
  • Thermal conductivity is a value specific to a material, and is influenced by the crystal structure, composition, defects, grain boundaries, and the like.
  • the grain boundaries are very thin, at 1 nm or less, so the effect of the grain boundaries on thermal conductivity is small, and in the case of highly transparent ceramics without coloring, the defects are thought to be very few, and in fact, at room temperature, a thermal conductivity equivalent to that of a single crystal is obtained. Therefore, it is the crystal structure and composition that determine the thermal conductivity.
  • Non-Patent Document 6 examples of the effect of composition on thermal conductivity include "Effects of rare-earth doping on thermal conductivity in Y 3 Al 5 O 12 crystals" (Non-Patent Document 6) and “Crystal growth and properties of (Lu,Y) 3 Al 5 O 12 " (Non-Patent Document 7).
  • Non-Patent Document 6 when yttrium aluminum garnet is doped with other rare earths, the thermal conductivity drops sharply.
  • the thermal conductivity may decrease if so-called mixtures such as solid solutions are added.
  • Non-Patent Document 8 shows the thermal conductivity when ytterbium is added to lutetium aluminum garnet. Since the atomic weight difference between lutetium and ytterbium is small at 2, it can be seen that the decrease in thermal conductivity is minimized.
  • Non-Patent Document 9 presents information on the laser damage threshold of TGG single crystal and TGG transparent ceramics due to pulsed laser light with a wavelength of 1,064 nm. Damage to the Faraday rotator leads to deterioration of transmittance, isolation, and beam quality, and in the worst case, the optical isolator may break down.
  • Possible optical damage caused by pulsed lasers includes ionization due to multiphoton absorption, electron avalanche collapse, and absorption by impurities.
  • materials with a large absorption coefficient tend to have a high laser damage resistance, so absorption management is important in order to provide Faraday rotators with a high laser damage threshold.
  • the transmittance of transparent ceramics is a value that reflects absorption and scattering (and reflection). Because transparent ceramics contain many scattering sources, it can be difficult to accurately determine the small amount of absorption from the transmittance.
  • LuTAG transparent ceramics are expected to have high thermal conductivity and a small thermal lens effect, but when an optical isolator equipped with the Faraday rotator was tested, a problem occurred in which the Faraday rotator was damaged when a certain high-power pulsed laser was irradiated.
  • Tb-containing rare earth aluminum garnet which has Tb(III) ions as a constituent element, also emits green light due to terbium(III) ions when excited.
  • Tb-containing rare earth aluminum garnet is used as a luminescent material, it is important that the emission wavelength does not overlap with the absorption bands of other elements as a means of increasing its luminescence efficiency.
  • ions of first transition metals often have d-d transition absorption and charge transfer absorption bands with oxide ions in the visible range, if they are contained as impurities in Tb-containing rare earth aluminum garnet, the emission of Tb ions is reabsorbed by the impurity ions, inhibiting the emission.
  • Luminescence efficiency is an index that indicates whether a substance emits strong light, and its value is determined by the ratio of the rate constant of the radiative transition from the lowest excited state that accompanies luminescence to the rate constant of the non-radiative transition that does not accompany luminescence. Specifically, it is defined as the probability that the excited state returns to the ground state by radiative transition. If the lifetime of the excited state (the time until the number of excited states decreases to 1/e) is ⁇ , then there is a proportional relationship with the luminescence quantum yield.
  • the amount of impurity ions and defects that cause quenching can be indirectly estimated by measuring the lifetime of the excited state. Furthermore, since luminescence is a phenomenon that occurs within the crystals of the base material, it is not easily affected by scattering that is specific to ceramics.
  • the present invention has been made in consideration of the above circumstances, and aims to provide LuTAG-based paramagnetic garnet-type transparent ceramics, magneto-optical materials, and magneto-optical devices with high laser damage thresholds.
  • the present inventors have intensively investigated the emission lifetime derived from the 5D4 ⁇ 7F5 transition of Tb(III) ions and the laser damage threshold as a Faraday rotator for Tb-containing rare earth aluminum garnet (LuTAG system ) , and found that Tb-containing rare earth aluminum garnet (paramagnetic garnet-type transparent ceramics) with a long emission lifetime has a high laser damage threshold, and Tb-containing rare earth aluminum garnet (paramagnetic garnet-type transparent ceramics) with a short emission lifetime has a low laser damage threshold, that is, they discovered that there is a correlation between the emission lifetime derived from the 5D4 ⁇ 7F5 transition of Tb(III ) ions and the laser damage threshold in paramagnetic garnet-type transparent ceramics.
  • the inventors have discovered that since the measurement of the luminescence lifetime is carried out non-destructively, it is possible to easily evaluate the laser damage resistance of the Faraday rotator. Based on these findings, the inventors have conducted extensive research and have completed the present invention.
  • one aspect of the present invention is a paramagnetic garnet-type transparent ceramic, which includes a sintered body of a garnet-type composite oxide containing terbium, lutetium, and aluminum and represented by the following formula (1): (Tb 1-x Lu x ) 3 Al 5 O 12 (1) (Wherein, 0.05 ⁇ x ⁇ 0.80.)
  • the lifetime of the luminescence originating from the 5 D 4 ⁇ 7 F 5 transition of the Tb(III) ions contained in the sintered body is 370 ⁇ s or more.
  • the paramagnetic garnet-type transparent ceramic according to the present invention preferably has a laser damage threshold of 10 J/cm 2 or more at a wavelength of 1,064 nm and a pulse width of 5 ns.
  • the paramagnetic garnet-type transparent ceramics according to the present invention preferably have a maximum emission intensity with excitation light of 350 nm wavelength between 500 and 600 nm wavelength.
  • the paramagnetic garnet-type transparent ceramics preferably further contain Sc as an additive in an amount of more than 10 ppm by mass and not more than 1,000 ppm by mass.
  • the paramagnetic garnet-type transparent ceramics preferably further contain Si as a sintering aid in an amount of 100 ppm by mass to 1,000 ppm by mass.
  • the paramagnetic garnet-type transparent ceramics of the present invention preferably have a thermal conductivity of 4.0 W/(m ⁇ K) or more at room temperature.
  • the paramagnetic garnet-type transparent ceramics according to the present invention preferably have a Verdet constant of 10 Rad/Tm or more at a wavelength of 1,064 nm.
  • the present invention is a magneto-optical material that is made of the above-mentioned paramagnetic garnet-type transparent ceramics.
  • the present invention is a magneto-optical device that is constructed using the above-mentioned magneto-optical material.
  • the magneto-optical device may be an optical isolator that has the paramagnetic garnet-type transparent ceramic as a Faraday rotator and has polarizing materials in front of and behind the optical axis of the Faraday rotator and can be used in the wavelength range of 0.9 ⁇ m to 1.1 ⁇ m.
  • the present invention provides a method for producing a paramagnetic garnet-type transparent ceramic, comprising the steps of: A step of pressure sintering a sintered body of a garnet-type composite oxide containing terbium, lutetium, and aluminum and represented by the following formula (1); (Tb 1-x Lu x ) 3 Al 5 O 12 (1) (Wherein, 0.05 ⁇ x ⁇ 0.80.)
  • the method includes a step of re-sintering the obtained pressure-sintered body by heating it to a temperature higher than the processing temperature in the pressure sintering, and a step of subjecting the obtained re-sintered body to an oxidation annealing treatment in an oxidation atmosphere at 1,400° C. or higher.
  • a paramagnetic garnet-type transparent ceramic having a laser damage threshold of 10 J/cm2 or more at a wavelength of 1,064 nm and a pulse width of 5 ns, and thus to provide a material suitable for forming magneto-optical devices such as optical isolators.
  • FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an optical isolator using the paramagnetic garnet-type transparent ceramic according to the present invention as a Faraday rotator.
  • the paramagnetic garnet-type transparent ceramic according to the present embodiment includes a sintered body of a garnet-type composite oxide represented by the following formula (1): (Tb 1-x Lu x ) 3 Al 5 O 12 (1) (Wherein, 0.05 ⁇ x ⁇ 0.80.)
  • the sintered body is characterized in that the lifetime of the luminescence derived from the 5D4 ⁇ 7F5 transition of the Tb(III) ions contained therein is 370 ⁇ s or more.
  • the site primarily occupied by Tb i.e., the first half of the parentheses in formula (1)
  • the site primarily occupied by Al is referred to as the B site.
  • terbium (Tb) is the element with the largest Verdet constant among trivalent rare earth ions, and has extremely small absorption in the 1,070 nm region (wavelength band 0.9 ⁇ m to 1.1 ⁇ m) used in fiber lasers, making it the most suitable element for use as a material for optical isolators in this wavelength range.
  • Tb(III) ions are easily oxidized to generate Tb(IV) ions.
  • Tb(IV) ions When Tb(IV) ions are generated in metal oxides, they absorb light over a wide range of wavelengths from ultraviolet to near infrared, so it is desirable to eliminate them as much as possible.
  • One strategy to prevent the generation of Tb(IV) ions is to adopt a crystal structure in which Tb(IV) ions are unstable, i.e., a garnet structure.
  • Lutetium (Lu) is an element that can be preferably used in this patent because it forms a garnet phase more stably than a perovskite phase when combined with aluminum to form a composite oxide.
  • it does not have characteristic absorption (ff transition) in the visible to near infrared region, and the difference in atomic weight with terbium is small at 16, making it an ideal element to add in developing a Faraday rotator with high thermal conductivity.
  • aluminum (Al) is a material with the smallest ionic radius among trivalent ions that can exist stably in oxides having a garnet structure, and is the element that can minimize the lattice constant of Tb-containing paramagnetic garnet-type oxides. If the lattice constant of the garnet structure can be reduced without changing the Tb content, it is preferable because the Verdet constant per unit length can be increased. Furthermore, since aluminum is a light metal, it has weak diamagnetism compared to gallium, and is expected to have the effect of relatively increasing the magnetic flux density generated inside the Faraday rotator, which is also preferable because it can increase the Verdet constant per unit length.
  • the Verdet constant of TAG ceramics is improved to 1.25 to 1.5 times that of TGG. Therefore, even if the relative concentration of terbium is reduced by replacing some of the terbium ions with lutetium ions, it is possible to keep the Verdet constant per unit length equal to or greater than that of TGG, or slightly lower, making it a suitable constituent element in the present invention.
  • the range of x is 0.05 ⁇ x ⁇ 0.80, and 0.05 ⁇ x ⁇ 0.45 is more preferable.
  • the Verdet constant at room temperature (23 ⁇ 15°C) and wavelength of 1,064 nm is 10 rad/(T ⁇ m) or more, and the material can be used as a Faraday rotator.
  • the Verdet constant at a wavelength of 1,064 nm is preferably 10 rad/(T ⁇ m) or more, more preferably 30 rad/(T ⁇ m) or more, and particularly preferably 36 rad/(T ⁇ m) or more.
  • the Verdet constant is 36 rad/(T ⁇ m) or more, it can be easily and particularly preferably replaced with the existing material, TGG single crystal, without changing the design of the part.
  • the range 0.05 ⁇ x ⁇ 0.45 is more preferable, in which the thermal lens effect is small and the total length required to rotate the 1,064 nm laser light by 45 degrees becomes short.
  • the paramagnetic garnet-type transparent ceramic of this embodiment contains the composite oxide represented by the above formula (1) as a main component. It is preferable to further add, as sub-components, SiO2 acting as a sintering aid and Sc2O3 as an additive for stabilizing the garnet structure, each in a range of 1,000 mass ppm or less in terms of metal.
  • Adding a small amount of SiO2 is preferable because it vitrifies during sintering at 1,400 ° C or higher, resulting in a liquid phase sintering effect and promoting the densification of the garnet-type ceramic sintered body.
  • the amount is less than 100 ppm by mass, the above effect cannot be sufficiently obtained, which is not preferable.
  • the Si content exceeds 1,000 ppm by mass, it is not preferable because a small amount of light absorption may occur due to crystal defects caused by the excess Si. Therefore, it is preferable to adjust the amount of addition so that it is 100 ppm by mass or more and 1,000 ppm by mass or less.
  • the source of silicon to be added is not limited to SiO2 , and molecular silicon such as tetraethoxysilane (TEOS) may also be used. In this case, it is preferable to adjust the amount of silicon added so that the amount is 1,000 mass ppm or less in terms of silicon.
  • TEOS tetraethoxysilane
  • the amount of Sc added is preferably more than 0 ppm, more preferably 5 ppm or more, and even more preferably 10 ppm or more.
  • the more Sc is added the higher the risk of antisite defect absorption occurs in which Tb and Lu enter the B site and Al enters the A site, which is not preferable.
  • Sc 2 O 3 in a range of 1,000 mass ppm or less in terms of metal Sc.
  • the paramagnetic garnet-type transparent ceramic of this embodiment exhibits Tb emission.
  • the lifetime of the emission derived from the 5 D 4 ⁇ 7 F 5 transition of the Tb (III) ion contained in the sintered body is 370 ⁇ s or more, preferably 500 ⁇ s or more.
  • the target paramagnetic garnet-type transparent ceramic is irradiated with excitation light having a wavelength of 350 nm, and the emission lifetime of the component having a wavelength of 545 nm in the emission is measured with a fluorescence spectrophotometer.
  • the time dependence of the emission decay of the emission component having a wavelength of 545 nm is measured, and the time at which the emission intensity becomes 1/e (about 37%) of the emission intensity at the start of emission is taken as the emission lifetime, assuming that this is a single emission lifetime.
  • the strongest intensity of the emission by the excitation light having a wavelength of 350 nm is preferably between 500 and 600 nm.
  • the paramagnetic garnet-type transparent ceramic of this embodiment preferably has a laser damage threshold of 10 J/cm2 or more at a wavelength of 1,064 nm and a pulse width of 5 ns. Since the paramagnetic garnet-type transparent ceramic of the present invention is intended to be used as a Faraday rotator, it is preferable that it is not damaged by a pulse laser (has laser damage resistance).
  • the method for determining whether or not "the laser damage threshold of a wavelength of 1,064 nm and a pulse width of 5 ns is 10 J/ cm2 or more" is to irradiate a laser beam having an energy density of 10 J/ cm2 , a wavelength of 1,064 nm, and a pulse width of 5 ns to any multiple locations (five or more, preferably ten or more) of the target paramagnetic garnet-type transparent ceramic, and observe the target area with an optical (polarized) microscope or the like. If the entire area is not damaged, it is determined that the "laser damage threshold is 10 J/ cm2 or more," and if even one location is damaged, it is determined that the "laser damage threshold is not 10 J/ cm2 or more.”
  • the laser damage threshold depends on the wavelength, pulse width and beam spot diameter of the irradiated laser light. Therefore, if it is not possible to perform a laser damage test with a wavelength of 1,064 nm, a wavelength of 5 ns and an irradiation beam diameter of 100 ⁇ m (Gaussian distribution 1/ e2 intensity), the laser damage threshold may be set to a wavelength of 1,064 nm and a pulse width of 5 ns by using LIDT scaling.
  • the formula (S1) can be applied as a general rule for scaling (converting) the initial conditions of wavelength ( ⁇ 1), pulse width ( ⁇ 1) and irradiation beam diameter ( ⁇ 1) to new wavelength ( ⁇ 2), pulse width ( ⁇ 2) and irradiation beam diameter ( ⁇ 2).
  • LIDT ( ⁇ 2, ⁇ 2, ⁇ 2) LIDT ( ⁇ 1, ⁇ 1, ⁇ 1) ⁇ ( ⁇ 1/ ⁇ 2) ⁇ ( ⁇ 2/ ⁇ 1) 1/2 ⁇ ( ⁇ 1/ ⁇ 2) 2 (S1) Therefore, using the following formula (S2), it is possible to convert the laser damage threshold (LIDT ) measured under conditions of wavelength ( ⁇ 1 (nm)), pulse width ( ⁇ 1 (ns)), and irradiation beam diameter ( ⁇ 1 ( ⁇ m)) different from those of wavelength 1,064 nm, wavelength 5 ns, and irradiation beam diameter 100 ⁇ m (Gaussian distribution 1/e2 intensity) to the laser damage threshold of a wavelength of 1,064 nm and a pulse width of 5 ns (irradiation beam diameter 100 ⁇ m).
  • LIDT (1064, 5, 100) LIDT ( ⁇ 1, ⁇ 1, ⁇ 1) ⁇ ( ⁇ 1/1064) ⁇ (5/ ⁇ 1) 1/2 ⁇ ( ⁇ 1/100) 2 (S2)
  • the laser damage threshold at a wavelength of 1,064 nm is 10 J/ cm2 or more.
  • the thermal conductivity of the paramagnetic garnet-type ceramic of this embodiment is 4.0 W/(m ⁇ K) or more.
  • Methods for measuring thermal conductivity are broadly divided into steady-state methods and unsteady-state methods.
  • Steady-state methods include the heat flow meter method
  • unsteady-state methods include the laser flash method, cyclic heating method, and hot-wire method.
  • any method may be used for measurement.
  • the laser flash method is the most preferred method from the viewpoint of allowing a smaller sample size than other measurement methods and facilitating the production of truly transparent ceramics.
  • the paramagnetic garnet-type transparent ceramics of this embodiment are preferably obtained by subjecting a pre-sintered body of the garnet-type composite oxide to hot-injection sintering (HIP), re-sintering this pressure-sintered body by heating it to a temperature exceeding the processing temperature of pressure sintering, and then annealing it in an oxidizing atmosphere, as described below.
  • HIP hot-injection sintering
  • a raw powder for sintering containing a garnet-type composite oxide powder (ceramic powder) represented by the above formula (1) is prepared, and this raw powder for sintering is used to press-form a predetermined shape, followed by degreasing and then pre-sintering to produce a densified sintered body.
  • HIP treatment As a subsequent step, it is preferable to perform HIP treatment as pressure sintering.
  • re-sintering is performed at a temperature higher than the HIP treatment temperature.
  • an annealing treatment is performed in an oxidizing atmosphere to recover oxygen deficiencies. This makes it possible to obtain a transparent garnet-type oxide ceramic with extremely low defect absorption and light scattering.
  • the raw powder for sintering and each step will be described below.
  • the method for producing the raw powder for sintering of the garnet-type complex oxide is not particularly limited, but may be a coprecipitation method, a pulverization method, a spray pyrolysis method, a sol-gel method, an alkoxide hydrolysis method, or any other synthesis method.
  • the obtained ceramic raw material of the rare earth complex oxide may be appropriately processed by a wet ball mill, a bead mill, a jet mill, a dry jet mill, a hammer mill, or the like to obtain a desired particle size.
  • the starting materials can be preferably terbium, lutetium, scandium, or aluminum metal powders, or the metal powders dissolved in an aqueous solution of nitric acid, sulfuric acid, uric acid, or the like, or oxide powders of the above metals.
  • the purity of the above raw materials is preferably 99.9% by mass or more, and particularly preferably 99.99% by mass or more.
  • the starting materials are weighed out in a predetermined amount so as to have a composition corresponding to formula (1), mixed, and then fired to obtain a calcined raw material of the desired metal oxide, which is then pulverized to obtain a raw material powder for sintering.
  • the calcination temperature at this time is preferably 900°C or more and less than 1,100°C, more preferably 900°C or more and 1,050°C or less, and even more preferably 1,000°C. If the calcination temperature is less than 900°C, the uniformity of the sintering raw material powder due to thermal diffusion becomes insufficient, and the volume change due to the phase change of terbium oxide during the sintering process increases the risk of the sintered body cracking.
  • the calcination time may be 1 hour or more, and the heating rate at that time is preferably 100°C/h or more and 500°C/h or less.
  • the atmosphere for the calcination is not particularly limited, but air, oxygen, and oxygen-containing atmospheres are particularly preferred.
  • the calcination device may be a vertical muffle furnace, a horizontal tubular furnace, a rotary kiln, etc., and is not particularly limited as long as it can reach the target temperature and oxygen flow.
  • "mainly composed” here refers to the main peak obtained from the powder X-ray diffraction results of the calcination raw material being a diffraction peak derived from the garnet structure. Note that when the ratio of the perovskite-type heterophase to the garnet parent phase is 1 ppm or less, the powder X-ray diffraction pattern will essentially only detect a garnet single phase pattern.
  • the raw powder for sintering preferably contains a sintering aid.
  • a sintering aid for example, tetraethoxysilane (TEOS) is added as a sintering aid together with the above starting raw material in an amount of 100 mass ppm to 1,000 mass ppm in terms of Si in the entire raw powder (garnet-type complex oxide powder + sintering aid), or SiO 2 powder is added in an amount of 100 mass ppm to 1,000 mass ppm in terms of Si in the entire raw powder (garnet-type complex oxide powder + sintering aid), mixed and fired to obtain a fired raw material.
  • the purity is preferably 99.9 mass% or more, and particularly preferably 99.99 mass% or more.
  • the sintering aid may be added during the preparation of the raw powder slurry described later.
  • a raw powder for sintering i.e., the above complex oxide powder
  • Such a selection may be made appropriately.
  • the obtained firing raw material is pulverized to obtain a raw material powder for sintering.
  • Either a dry or wet pulverization method can be selected, but it is necessary to pulverize so that the target ceramics are highly transparent.
  • the firing raw material is slurried by various pulverization (dispersion) methods such as a ball mill, a bead mill, a homogenizer, a jet mill, and ultrasonic irradiation, and then pulverized (dispersed) to primary particles.
  • the dispersion medium of this wet slurry is not particularly limited as long as it can make the final ceramics highly transparent, and examples of the dispersion medium include alcohols such as lower alcohols with 1 to 4 carbon atoms and pure water.
  • various organic additives may be added to this wet slurry for the purpose of improving the quality stability and yield in the subsequent ceramic manufacturing process. In the present invention, these are also not particularly limited. In other words, various dispersants, binders, lubricants, plasticizers, etc. can be suitably used. However, it is preferable to select high-purity types of organic additives that do not contain unnecessary metal ions.
  • wet pulverization the dispersion medium of the slurry is finally removed to obtain a raw material powder for sintering.
  • a normal press molding process can be suitably used. That is, a very common press process in which the material is filled in a mold and pressed from a certain direction, or a process in which the material is sealed in a deformable waterproof container, A cold isostatic pressing (CIP) process or a warm isostatic pressing (WIP) process using hydrostatic pressure can be suitably used.
  • CIP cold isostatic pressing
  • WIP warm isostatic pressing
  • the applied pressure can be appropriately adjusted while checking the relative density of the resulting molded body, and there is no particular restriction.
  • the manufacturing cost can be reduced by controlling the pressure within a range of about 300 MPa or less, which is compatible with a commercially available CIP device.
  • a hot press process in which not only the molding process but also sintering is performed at once during molding may be performed.
  • a discharge plasma sintering process, a microwave heating process, etc. can be suitably used.
  • press molding it is also possible to manufacture a molded body by a casting method. Pressure casting, centrifugal casting, extrusion molding, etc.
  • the forming method of the above can also be adopted by optimizing the combination of the shape and size of the oxide powder, which is the starting material, and various organic additives.
  • a normal degreasing process can be suitably used. That is, a temperature-raising degreasing process using a heating furnace can be used.
  • the type of atmospheric gas used in this process is not particularly limited.
  • the degreasing temperature is not particularly limited, but if a raw material containing organic additives is used, the temperature should be raised to a temperature at which the organic components can be decomposed and eliminated. It is preferred.
  • a pre-sintered body is prepared as a sintered body before pressure sintering, which is preferably densified to a relative density of 94% or more and preferably has an average sintered grain size of 5 ⁇ m or less. At this time, it is necessary to determine the conditions of temperature and holding time so that the sintered grain size falls within the desired range.
  • a general sintering process can be preferably used. That is, a heating sintering process such as a resistance heating method or an induction heating method can be preferably used.
  • the atmosphere is not particularly limited, and various atmospheres such as air, inert gas, oxygen gas, hydrogen gas, and helium gas can be preferably used, but sintering under reduced pressure (in a vacuum) is more preferably used.
  • the degree of vacuum for pre-sintering is preferably less than 1 ⁇ 10 ⁇ 1 Pa, and more preferably less than 1 ⁇ 10 ⁇ 2 Pa.
  • the sintering temperature in the pre-sintering step is preferably 1,450 to 1,650°C, and particularly preferably 1,500 to 1,600°C. This range of sintering temperature is preferable because it promotes densification while suppressing heterophase precipitation and grain growth.
  • a sintering hold time of several hours in the pre-sintering step of the present invention is sufficient, but it is preferable to densify the pre-sintered body to a relative density of 94% or more. If the relative density of the pre-sintered body exceeds 99%, it becomes difficult for plastic deformation to occur in the particles inside the sintered body during the subsequent hot-press sintering (HIP), and it becomes difficult to remove any bubbles remaining in the sintered body. For this reason, the relative density of the pre-sintered body is preferably 99% or less at most, and more preferably 98% or less.
  • the average sintered grain size of the crystal grains of the pre-sintered body is preferably 5 ⁇ m or less, more preferably 3 ⁇ m or less, even more preferably 2.5 ⁇ m or less, and particularly preferably 1 ⁇ m or less.
  • the average sintered grain size of the sintered grains can be adjusted in consideration of the raw material type, atmosphere, sintering temperature, and holding time. If the sintered grain size is larger than 5 ⁇ m, plastic deformation will be difficult to occur in the subsequent hot-ip sintering, and it may be difficult to remove any air bubbles remaining in the pre-sintered body.
  • a hot isostatic pressing (HIP) process can be performed as a pressure sintering process.
  • the type of pressurized gas medium at this time can be an inert gas such as argon or nitrogen, or Ar- O2 .
  • the pressure applied by the pressurized gas medium is preferably 50 to 300 MPa, more preferably 100 to 300 MPa. If the pressure is less than 50 MPa, the transparency improvement effect may not be obtained, and if the pressure exceeds 300 MPa, even if the pressure is increased, no further transparency improvement can be obtained, and the load on the device may be excessive, which may damage the device. It is convenient and preferable that the applied pressure is 196 MPa or less, which can be processed with a commercially available HIP device.
  • the processing temperature in the HIP treatment is preferably 1000°C or higher, and more preferably 1100°C or higher, since there is a risk that the transparency improvement effect of the sintered body will be almost ineffective if the processing temperature is less than 1000°C.
  • the processing temperature in the HIP treatment is preferably 1780°C or lower, and more preferably 1700°C or lower, since if grain growth occurs during the HIP treatment, it will become difficult to remove bubbles.
  • the heater material, heat insulating material, and processing vessel for HIP treatment are not particularly limited, but graphite, molybdenum (Mo), tungsten (W), and platinum (Pt) can be preferably used, and yttrium oxide and gadolinium oxide can also be preferably used as the processing vessel.
  • Mo molybdenum
  • W tungsten
  • Pt platinum
  • yttrium oxide and gadolinium oxide can also be preferably used as the processing vessel.
  • platinum (Pt) can be used as the heater material, heat insulating material, and processing vessel, and the pressurized gas medium can be Ar- O2 , which is preferable because it can prevent the occurrence of oxygen deficiency during HIP treatment.
  • graphite is preferable as the heater material and heat insulating material, but in this case, it is preferable to select graphite, molybdenum (Mo), or tungsten (W) as the processing vessel, and further select yttrium oxide or gadolinium oxide as a double vessel inside it, and then fill the vessel with an oxygen release material, since the amount of oxygen deficiency during HIP treatment can be suppressed to a minimum.
  • Mo molybdenum
  • W tungsten
  • re-sintering process In the manufacturing method of this embodiment, after the pressure sintering (HIP) step is completed, re-sintering can be performed in order to grow the grains of the obtained transparent ceramics.
  • the temperature of re-sintering is a temperature higher than the processing temperature in pressure sintering, specifically, 1,650°C or higher is preferable, and 1,700°C or higher is even more preferable. Temperatures below 1,650°C are not preferable because grain growth does not occur.
  • the average grain size of the crystal grains by re-sintering is preferably 10 ⁇ m or more, more preferably 15 ⁇ m or more, and particularly preferably 20 ⁇ m or more.
  • the holding time for the resintering process is not particularly limited, but is preferably 5 hours or more, more preferably 10 hours or more, and even more preferably 20 hours or more. By holding for a long time, particularly 20 hours or more, the crystal grains will grow and scattering can be reduced.
  • the temperature and holding time for the resintering process can be adjusted appropriately after checking the average grain size. However, generally, if the sintering temperature is raised too high, unexpected abnormal grain growth will occur, making it difficult to obtain a homogeneous sintered body. Therefore, it is preferable to allow a certain amount of leeway for the resintering temperature, and to adjust the size of the average grain size of the resintered body by extending the holding time.
  • Oxidation annealing treatment process The resintered body that has undergone the above series of treatments may have some oxygen deficiency, especially due to reduction in the pressure sintering (HIP) process, and may have a gray to dark blue appearance. Therefore, an oxidation annealing treatment (oxygen deficiency recovery treatment) is performed in an oxidizing atmosphere (oxygen-containing atmosphere) such as air.
  • the annealing temperature is 1,400°C or higher, preferably 1,450°C or higher. It is also preferable that it is 1,500°C or lower.
  • the holding time is not particularly limited, but it is sufficient to perform the treatment for a time sufficient to recover the oxygen deficiency, preferably 10 hours or more, and more preferably 20 hours or more.
  • a slight oxidation HIP treatment may be performed.
  • the oxygen deficiency can be restored, so that the size and number of the scattering source (scattering contrast source) can be controlled within a specified range, and a paramagnetic garnet-type transparent ceramic body with little absorption due to oxygen deficiency can be obtained.
  • the essential coloring (absorption) of the material due to the addition of colored elements such as dopants and impurities for imparting functions cannot be removed.
  • the optical loss is preferably ⁇ /2 or less, and more preferably ⁇ /8 or less.
  • the optical loss can be further reduced by forming an anti-reflection film on the optically polished surface. It is possible.
  • a paramagnetic garnet-type transparent ceramic which is a sintered body of a paramagnetic garnet-type composite oxide containing terbium represented by the above formula (1), and in which the lifetime of the emission derived from the 5D4 ⁇ 7F5 transition of the Tb(III ) ion contained in the sintered body is 370 ⁇ s or more.
  • the laser damage threshold at a wavelength of 1,064 nm and a pulse width of 5 ns can be preferably 10 J/ cm2 or more.
  • the magneto-optical device of this embodiment is constructed using the above-mentioned paramagnetic garnet-type transparent ceramic.
  • the above-mentioned paramagnetic garnet-type transparent ceramic can be used as a magneto-optical material, and specifically, it is preferable to configure and use a magneto-optical device by applying a magnetic field parallel to the optical axis of this paramagnetic garnet-type transparent ceramic, and then setting a polarizer and an analyzer so that their optical axes are shifted by 45 degrees from each other.
  • the paramagnetic garnet-type transparent ceramic of this embodiment is suitably used as a magneto-optical device, particularly as a Faraday rotator of an optical isolator with a wavelength of 0.9 to 1.1 ⁇ m.
  • the optical isolator 100 is a cross-sectional view showing an example of an optical isolator, which is a magneto-optical device having a Faraday rotator made of the paramagnetic garnet-type transparent ceramic of this embodiment as an optical element.
  • the optical isolator 100 has a Faraday rotator 110 made of the above-mentioned paramagnetic garnet-type transparent ceramic, a polarizer 120 made of a polarizing material, and an analyzer 130 inside its housing 150. These are arranged in the order of the polarizer 120, the Faraday rotator 110, and the analyzer 130 along the optical axis 112 of the Faraday rotator.
  • the polarized light vibration plane of the polarizer 120 and the polarized light vibration plane of the analyzer 130 are arranged so that the relative angle is 45°.
  • the optical isolator 100 also has a magnet 140 for applying a magnetic field to the Faraday rotator 110 on at least one of the side surfaces of the Faraday rotator 110 inside the housing 150.
  • Such an optical isolator 100 can be suitably used in an industrial fiber laser device (not shown).
  • the optical isolator can prevent the reflected light of the laser light emitted from the laser light source from returning to the light source, causing the oscillation to become unstable.
  • the method for judging the laser damage resistance of a paramagnetic garnet-type transparent ceramic according to the present embodiment judges the laser damage resistance of a paramagnetic garnet-type transparent ceramic including a sintered body of a garnet-type composite oxide represented by the following formula (1) based on the lifetime of the emission derived from the 5D4 ⁇ 7F5 transition of Tb(III) ions included in the sintered body. (Tb 1-x Lu x ) 3 Al 5 O 12 (1) (Wherein, 0.05 ⁇ x ⁇ 0.80.)
  • the lifetime of the emission derived from the 5D4 ⁇ 7F5 transition of the Tb(III) ion is 370 ⁇ s or more, it is preferable to judge that the laser damage threshold at a wavelength of 1,064 nm and a pulse width of 5 ns is 10 J/ cm2 or more.
  • the method for measuring the emission lifetime has been described above, so a description thereof will be omitted here.
  • Example 1 shows the case where the value of x in formula (1) is 0.05 ⁇ x ⁇ 0.80.
  • Lutetium oxide powder, terbium oxide powder, and scandium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd., and aluminum oxide powder manufactured by Taimei Chemical Co., Ltd. were obtained.
  • tetraethyl orthosilicate (TEOS) manufactured by Kishida Chemical Co., Ltd. and polyvinyl alcohol manufactured by Kanto Chemical Co., Ltd. were obtained.
  • the purity of the powder raw materials was 99.9 mass% or more, and the purity of the liquid raw materials was 99.999 mass% or more.
  • a total of seven types of raw material powders with the final composition shown in Table 1 were prepared by adjusting the mixing ratio as follows.
  • each was placed in a polyethylene pot, taking care to prevent mixing, and each was dispersed and mixed in ethanol using a ball mill.
  • the processing time was 24 hours.
  • Polyvinyl alcohol was added as a binder to the oxide powder at 1.0% by mass. After that, a spray drying process was carried out to produce granular raw materials with an average particle size of 20 ⁇ m.
  • the degreased molded body was placed in a vacuum furnace and pre-sintered at 1,600°C for 2 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa to obtain a total of seven pre-sintered bodies.
  • the sintered relative density of each sample was 94% or more.
  • Each pre-sintered body obtained was placed in a HIP furnace made of a carbon heater and subjected to pressure sintering (HIP) treatment under conditions of 196 MPa, 1,600°C, and 3 hours in Ar.
  • HIP pressure sintering
  • the pressure sintered body was placed in a vacuum furnace again and re-sintered at 1,700°C for 20 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa to obtain a re-sintered body.
  • the re-sintered body was subjected to oxidation annealing treatment at 1,450°C in air for 30 hours.
  • Each of the transparent ceramics and TGG single crystals thus obtained was ground into a cylindrical shape with a diameter of 10 mm, and then ground and polished to a length of 10 mm to produce samples.
  • Thermal conductivity was measured according to JIS R 1611-1997 (Testing method for thermal diffusivity, specific heat, and thermal conductivity of fine ceramics by laser flash method). For each sample, a disk-shaped transparent ceramic sintered body with a diameter of 10 mm and a thickness of 2 mm was prepared, and laser irradiation was performed on one side. The difference in temperature rise between the laser irradiated side and the opposite side was measured, and the thermal diffusivity ⁇ was determined by the half-time method. The density ⁇ was measured by the Archimedes method, and the specific heat C was measured by differential scanning thermogravimetry. The thermal conductivity was determined by the product of the thermal diffusivity ⁇ , density ⁇ , and specific heat C.
  • each obtained sample was inserted into the center of a neodymium-iron-boron magnet with an outer diameter of 32 mm, an inner diameter of 6 mm, and a length of 40 mm, and polarizers were inserted at both ends.
  • a high-power laser beam diameter 1.6 mm
  • a high-power laser beam with a wavelength of 1,064 nm was incident from both end faces to determine the Faraday rotation angle ⁇ .
  • the Faraday rotation angle ⁇ was defined as the angle showing the maximum transmittance when the polarizer on the output side was rotated.
  • the Verdet constant was calculated based on the following formula.
  • the magnitude (H) of the magnetic field applied to the sample was calculated by simulation from the dimensions of the above measurement system, the residual magnetic flux density (Br), and the coercive force (Hc).
  • ⁇ V ⁇ H ⁇ L (In the formula, ⁇ is the Faraday rotation angle (Rad), V is the Verdet constant (Rad/T ⁇ m), H is the magnitude of the magnetic field (T), and L is the length of the Faraday rotator (0.020 m in this case).)
  • the luminescence lifetime was measured using a modular fluorescence spectrophotometer Fluorolog-3 (manufactured by HORIBA Seisakusho). The measurement location was a cylindrically ground rough surface. The excitation light was 350 nm, and the lifetime was measured for the luminescence component with a wavelength of 545 nm. When the excitation light was applied, the measured sample became excited and returned to the ground state while releasing energy via the lowest excited state 5D4 . At this time, luminescence occurred. Note that luminescence with maximum intensity was observed between wavelengths of 500 and 600 nm in all samples. In this case, the change in emission intensity over time F(t) is given by the following formula.
  • the luminescence lifetime ⁇ was determined by measuring the time dependence of luminescence decay and by the least squares method using the above formula, assuming a single luminescence lifetime.
  • the laser damage threshold was measured using a Nd:YAG laser with a wavelength of 1,064 nm and a pulse width of 5 ns.
  • the irradiation angle was perpendicular to the polished surface (optical end surface of the sample), the irradiation size was a beam diameter of 100 ⁇ m (Gaussian distribution 1/e 2 intensity), and the energy density was 10 to 11 J/cm 2.
  • 10 shots were irradiated while changing the position within the optical effective area of the optical end surface of the sample, and the number of damages was counted with a polarizing microscope.
  • the emission lifetime of the transparent ceramics of Examples 1-1 to 1-7 was 383 ⁇ s to 1080 ⁇ s.
  • the number of laser damages of all the transparent ceramics at this time was 0.
  • the emission lifetime of the TGG single crystal was 182 ⁇ s, and the number of laser damages at this time was 10.
  • the transparent ceramics with an emission lifetime of 383 ⁇ s or more had a laser damage threshold of 10 J/cm 2 or more.
  • the transparent ceramics containing lutetium Examples 1-1 to 1-7) had a higher thermal conductivity than the TGG single crystal (Reference Example 1-1), and a Verdet constant of 10 Rad/T ⁇ m or more.
  • Example 2 As Example 2, the case where the amount of Si and Sc added was changed is shown. Lutetium oxide powder, terbium oxide powder, and scandium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd., and aluminum oxide powder manufactured by Taimei Chemical Co., Ltd. were obtained. In addition, tetraethyl orthosilicate (TEOS) manufactured by Kishida Chemical Co., Ltd. and polyvinyl alcohol manufactured by Kanto Chemical Co., Ltd. were obtained. The purity of the powder raw material was 99.9 mass% or more, and the purity of the liquid raw material was 99.999 mass% or more. Using the above raw materials, a total of seven types of raw material powders with the final composition shown in Table 2 were prepared by adjusting the mixing ratio as follows.
  • TEOS tetraethyl orthosilicate
  • the degreased molded body was placed in a vacuum furnace and pre-sintered at 1,600°C for 2 hours under reduced pressure of less than 1.0 ⁇ 10-2 Pa to obtain a total of seven pre-sintered bodies. At this time, the sintered relative density of each sample was 94% or more.
  • Each pre-sintered body obtained was placed in a carbon heater HIP furnace and subjected to pressure sintering (HIP) treatment under conditions of 196 MPa, 1,600°C, and 3 hours in Ar.
  • HIP pressure sintering
  • the pressure sintered body was placed in a vacuum furnace again and re-sintered at 1,700°C for 20 hours under reduced pressure of less than 1.0 ⁇ 10-2 Pa to obtain a re-sintered body.
  • the re-sintered body was subjected to oxidation annealing treatment at 1,450°C in air for 30 hours.
  • Each transparent ceramic thus obtained was ground into a cylindrical shape with a diameter of 10 mm, and then ground and polished to a length of 10 mm.
  • the emission lifetime of all transparent ceramics with an Si addition amount of 100 mass ppm or more and 1,000 mass ppm or less and an Sc addition amount of 100 mass ppm was 370 ⁇ s or more, and the number of laser damages of the transparent ceramics at this time was all 0.
  • the emission lifetime of all transparent ceramics with an Si addition amount of 100 mass ppm and an Sc addition amount of 0 mass ppm or more and 1,000 mass ppm or less was 374 ⁇ s or more.
  • the number of laser damages of the transparent ceramics at this time was all 0.
  • Comparative Examples 2-1 to 2-2 were not made transparent, and measurements could not be performed.
  • the emission lifetime of all transparent ceramics was 370 ⁇ s or more and the laser damage threshold of transparent ceramics with an Si addition amount of 100 mass ppm or more and 1,000 mass ppm or less was 10 J / cm 2 or more. It was also confirmed that the emission lifetime of all the transparent ceramics was 374 ⁇ s or more, and that the transparent ceramics having an Sc addition amount of 0 mass ppm or more and 1,000 mass ppm or less had a laser damage threshold of 10 J/cm 2 or more.
  • Example 3 As Example 3, the case where oxidation annealing was performed at 1,450°C for 30 hours in air and the case where oxidation annealing was not performed are shown. Lutetium oxide powder, terbium oxide powder, and scandium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd., and aluminum oxide powder manufactured by Taimei Chemical Co., Ltd. were obtained. In addition, tetraethyl orthosilicate (TEOS) manufactured by Kishida Chemical Co., Ltd. and polyvinyl alcohol manufactured by Kanto Chemical Co., Ltd. were obtained. The purity of the powder raw material was 99.9% by mass or more, and the purity of the liquid raw material was 99.999% by mass or more. Using the above raw materials, a total of two types of raw material powders with the final composition shown in Table 3 were prepared by adjusting the mixing ratio as follows.
  • each was placed in a polyethylene pot, taking care to prevent mixing, and each was dispersed and mixed in ethanol using a ball mill.
  • the processing time was 24 hours.
  • Polyvinyl alcohol was added as a binder to the oxide powder at 1.0% by mass. After that, a spray drying process was carried out to produce granular raw materials with an average particle size of 20 ⁇ m.
  • the degreased molded body was placed in a vacuum furnace and pre-sintered at 1,600°C for 2 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa to obtain a total of two types of pre-sintered bodies.
  • the sintered relative density of each sample was 94% or more.
  • Each pre-sintered body obtained was placed in a carbon heater HIP furnace and subjected to pressure sintering (HIP) treatment under conditions of 196 MPa, 1,600°C, and 3 hours in Ar.
  • HIP pressure sintering
  • the pressure sintered body was placed in a vacuum furnace again and re-sintered at 1,700°C for 20 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa to obtain a re-sintered body.
  • the re-sintered body was subjected to oxidation annealing treatment at 1,450°C in air for 30 hours.
  • the degreased molded body was placed in a vacuum heating furnace and treated at 1,600°C for 2 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa to obtain a total of two types of pre-sintered bodies.
  • the sintered relative density of each sample was 94% or more and 99% or less.
  • Each of the obtained sintered bodies was placed in a HIP furnace made of a carbon heater and HIP-treated under conditions of 196 MPa, 1,600°C, and 3 hours in Ar to obtain a transparent body.
  • the HIP-treated sintered body was placed again in a vacuum heating furnace and treated at 1,700°C for 20 hours under reduced pressure of less than 1.0 ⁇ 10 ⁇ 2 Pa.
  • the sintered body was not subjected to oxidation annealing treatment.
  • the transparent ceramics (Examples 3-1 to 3-2) annealed in air at 1,450°C for 30 hours had an emission lifetime of 378 ⁇ s or more, and the number of laser damages at this time was 0.
  • the transparent ceramics (Comparative Examples 3-1 to 3-2) that were not subjected to oxidation annealing had an emission lifetime of 221 ⁇ s or less, and the number of laser damages at this time was 10.
  • the emission lifetime became 378 ⁇ s or more, and a transparent ceramic with a laser damage threshold of 10 J/ cm2 or more was obtained.
  • Example 4 In Example 3-1, the oxidation annealing temperature was 1,300° C. (Comparative Example 4-1), 1,400° C. (Example 4-1), and 1,500° C. (Example 4-2), and treatment was performed for 30 hours under the same conditions as in Example 3-1, and paramagnetic garnet-type transparent ceramic samples were produced. The evaluation results are shown in Table 4.
  • the luminescence lifetime of the paramagnetic garnet-type transparent ceramics with oxidation annealing temperatures of 1,400°C and 1,500°C was 371 to 388 ⁇ s, and the number of laser damages was 0.
  • the luminescence lifetime of the paramagnetic garnet-type transparent ceramics with oxidation annealing temperatures of 1,300°C was 264 ⁇ s, and the number of laser damages was 10.
  • the luminescence lifetime of the paramagnetic garnet-type transparent ceramics with oxidation annealing temperatures of 1,400°C or higher was 371 ⁇ s or higher, and the laser damage threshold at this time was 10 J/ cm2 or higher.
  • Example 5 As an example of a magneto-optical device, an optical isolator is constructed using a paramagnetic garnet-type transparent ceramic with zero laser damage (Example 2-1) as Example 5 and a paramagnetic garnet-type transparent ceramic with 10 laser damage (Comparative Example 2-1) as Comparative Example 5. Optical isolators with the same configuration as in Patent Document 5 were fabricated using each transparent ceramic as a Faraday rotator.
  • the durability test of the optical isolator was evaluated by transmitting a pulsed laser beam with a wavelength of 1,030 nm, a pulse width of 14 ps, an average power of 150 W, and a repetition rate of 600 kHz through the optical isolator.
  • the beam diameter was set to approximately parallel light with a diameter of 1.0 mm (Gaussian distribution 1/ e2 intensity).
  • the durability of the optical isolator was evaluated by expanding the transmitted light with an expander and observing the time dependence of the transmitted light intensity with a power meter.

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  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

L'invention concerne une céramique transparente de type grenat paramagnétique qui est basée sur LuTAG et a un seuil d'endommagement laser élevé, un matériau magnéto-optique et un dispositif magnéto-optique.　La céramique transparente de type grenat paramagnétique peut être obtenue par frittage sous pression d'un corps fritté d'un oxyde composite de type grenat représenté par la formule (1), par re-frittage du corps fritté sous pression par chauffage à une température supérieure à la température de traitement dans le frittage sous pression, et par recuit oxydatif du corps re-fritté dans une atmosphère oxydante à 1400°C ou plus. Dans la céramique transparente de type grenat paramagnétique, la durée de vie de la luminescence dérivée de la transition 5D4→7F5 des ions Tb(III) contenus dans le corps fritté est de 370 µs ou plus.　Formule (1) : (Tb1-xLux)3Al5O12 (où 0,05≦x≦0,80).　Le dispositif magnéto-optique est un isolateur optique qui est pourvu d'un rotateur de Faraday formé de la céramique transparente de type grenat paramagnétique et d'un matériau polarisant positionné devant et derrière l'axe optique de celui-ci, et qui peut être utilisé dans une plage de longueurs d'onde de 0,9 à 1,1 µm inclus.
PCT/JP2023/040097 2022-12-20 2023-11-07 Céramique transparente de type grenat paramagnétique, matériau magnéto-optique et dispositif magnéto-optique WO2024135132A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019199387A (ja) * 2018-05-18 2019-11-21 信越化学工業株式会社 常磁性ガーネット型透明セラミックス、磁気光学材料及び磁気光学デバイス
JP2019207340A (ja) * 2018-05-30 2019-12-05 信越化学工業株式会社 ファラデー回転子用透明セラミックスの製造方法
WO2022054593A1 (fr) * 2020-09-09 2022-03-17 信越化学工業株式会社 Procédé de production de céramique transparente de type grenat paramagnétique, céramique transparente de type grenat paramagnétique, matériau optique magnétique et dispositif optique magnétique
WO2022085679A1 (fr) * 2020-10-20 2022-04-28 株式会社ワールドラボ CÉRAMIQUE DE GRENAT DE TERRE RARE-ALUMINIUM CONTENANT DU Tb ET PROCÉDÉ POUR LA FABRICATION DE CELLE-CI

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019199387A (ja) * 2018-05-18 2019-11-21 信越化学工業株式会社 常磁性ガーネット型透明セラミックス、磁気光学材料及び磁気光学デバイス
JP2019207340A (ja) * 2018-05-30 2019-12-05 信越化学工業株式会社 ファラデー回転子用透明セラミックスの製造方法
WO2022054593A1 (fr) * 2020-09-09 2022-03-17 信越化学工業株式会社 Procédé de production de céramique transparente de type grenat paramagnétique, céramique transparente de type grenat paramagnétique, matériau optique magnétique et dispositif optique magnétique
WO2022085679A1 (fr) * 2020-10-20 2022-04-28 株式会社ワールドラボ CÉRAMIQUE DE GRENAT DE TERRE RARE-ALUMINIUM CONTENANT DU Tb ET PROCÉDÉ POUR LA FABRICATION DE CELLE-CI

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