WO2012020704A1 - Inorganic-oxide fluorescent material and thin film of white fluorescent material - Google Patents

Inorganic-oxide fluorescent material and thin film of white fluorescent material Download PDF

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WO2012020704A1
WO2012020704A1 PCT/JP2011/067934 JP2011067934W WO2012020704A1 WO 2012020704 A1 WO2012020704 A1 WO 2012020704A1 JP 2011067934 W JP2011067934 W JP 2011067934W WO 2012020704 A1 WO2012020704 A1 WO 2012020704A1
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thin film
catio
white
phosphor
atomic
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PCT/JP2011/067934
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French (fr)
Japanese (ja)
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浩 高島
徹 京免
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独立行政法人産業技術総合研究所
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Priority claimed from JP2010178264A external-priority patent/JP5674001B2/en
Priority claimed from JP2010188266A external-priority patent/JP5674005B2/en
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Publication of WO2012020704A1 publication Critical patent/WO2012020704A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/74—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing arsenic, antimony or bismuth
    • C09K11/7407—Chalcogenides
    • C09K11/7421—Chalcogenides with alkaline earth metals

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  • the present invention uses a phosphor of a perovskite oxide having excellent chemical stability and color rendering properties and a white phosphor thin film, a method for producing the same, and a phosphor and a white phosphor thin film.
  • the present invention relates to a light emitting device.
  • lighting fixtures mainly used are incandescent bulbs and fluorescent lamps.
  • a fluorescent lamp can efficiently emit ultraviolet rays of 254 nm and 185 nm by discharging mercury at a low vapor pressure. The ultraviolet light is converted into white light by the phosphor applied in the glass tube.
  • Fluorescent lamps generate much less heat than incandescent bulbs and require several percent of power to obtain the same brightness.
  • regulations have been issued in Europe to prohibit the use of harmful substances such as lead and mercury in electrical and electronic equipment related devices and devices in the future due to the RoHS directive. This is expected to limit the use of fluorescent lamps that have been used so far, and the development of new lighting devices is urgently needed.
  • Candidates for future lighting include white LEDs, organic / inorganic EL, etc., but what has been determined at this time has not been determined, and the development of white phosphors with excellent chemical stability is required. It has been.
  • Patent Documents 1 and 2 disclose fluorescence characteristics of a polycrystalline Sn perovskite oxide system.
  • Patent Document 2 shows that red, blue, and green are realized with a phosphor of a perovskite-based material using an oxide of an alkaline earth metal and zirconium as a fluorescent matrix.
  • Non-Patent Document 1 shows that fluorescence characteristics can be obtained by substituting Ca, Sr, and Ba in a polycrystalline ASnO 3 perovskite structure.
  • Non-Patent Document 2 shows that blue fluorescence can be obtained with a polycrystalline Sn-based layered perovskite structure.
  • Non-Patent Document 3 shows red fluorescence characteristics in a polycrystalline layered perovskite Sr n + 1 Ti n O 3n + 1 system.
  • Non-Patent Document 4 shows the red fluorescence characteristic of polycrystalline Pr atom substitution (CaSrBa) TiO 3 .
  • Non-Patent Document 5 shows the red fluorescence characteristic of CaTiO 3 : Pr.
  • Patent Document 3 shows the white phosphor.
  • Patent Document 3 discloses aM 1 O.bM 2 2 O 3 .cM 3 O 2 (where M 1 is one or more elements selected from the group consisting of Ba, Sr, Ca, Mg, and Zn; 2 is one or more elements selected from the group consisting of Al, Sc, Ga, Y, In, La, Gd and Lu, and M 3 is selected from the group consisting of Si, Ti, Ge, Zr, Sn and Hf.
  • An activator wherein a is 8 or more and 10 or less, b is 0.8 or more and 1.2 or less, and c is 5 or more and 7 or less.
  • the oxide of Patent Document 3 does not have a perovskite structure.
  • Non-Patent Document 6 shows that red, blue, green, and white fluorescence characteristics can be obtained by ultraviolet excitation in a tin-based perovskite structure-related oxide thin film.
  • Non-Patent Document 8 shows that red, blue, and green fluorescence appear by ultraviolet excitation by adding an appropriate rare earth element in a zirconia-based perovskite oxide thin film.
  • the present inventors have shown that red fluorescence appears by ultraviolet excitation when Pr is added in a (CaSr) TiO 3 perovskite oxide thin film (see Non-Patent Document 7).
  • Patent Document 4 an excellent red phosphor oxide epitaxial thin film formed by a pulse laser deposition method using a polycrystalline target material in which an aluminum element is added to a Pr-substituted SrTiO 3 perovskite oxide. It has been shown that the fluorescence characteristics of Specifically, it is shown that an oxide phosphor epitaxial thin film is formed on a substrate by epitaxial growth at a temperature of 600 ° C. or higher and 800 ° C. or lower by a pulse laser deposition method.
  • Patent Document 5 by the present inventors shows that red, blue, green, and white fluorescence characteristics can be obtained by ultraviolet excitation in a tin-based perovskite structure-related oxide thin film. Specifically, it is shown that an oxide phosphor epitaxial thin film is formed on a substrate by epitaxial growth at a temperature of 600 ° C. or higher and 800 ° C. or lower by a pulse laser deposition method.
  • the oxide polycrystal has been able to obtain a good phosphor in recent years, and the development of three primary colors of red, green, and blue, which are the basis of display production with the thin film, has been carried out. There was a problem that the color rendering was not sufficient.
  • EL development using thin films is indispensable, and development of oxide white phosphor epitaxial thin films is desired.
  • Non-Patent Document 6 and Patent Document 5 show a white fluorescent property in a tin-based perovskite structure-related oxide thin film, but a problem of poor color rendering because white was realized by the correlation of a plurality of sharp emission spectra. was there.
  • An object of the present invention is to solve these problems, and an object of the present invention is to provide a phosphor having a white fluorescent property with excellent color rendering property that can be used in a lighting fixture by using a perovskite oxide. To do. It is another object of the present invention to provide a manufacturing method that improves white fluorescent characteristics. It is another object of the present invention to provide a light emitting device using a perovskite oxide.
  • Another object of the present invention is to provide a phosphor epitaxial thin film having a white fluorescent property having excellent color rendering properties by ultraviolet excitation using a perovskite oxide. Moreover, it aims at providing the manufacturing method of the white fluorescent substance epitaxial thin film which improves a white fluorescence characteristic. It is another object of the present invention to provide a light emitting device using a perovskite oxide white phosphor epitaxial thin film.
  • the present invention introduces a small amount of bismuth Bi having an atomic number of 83 into CaTiO 3 , which is known as a perovskite type oxide, and has a white fluorescent property with excellent broad color rendering in a wavelength region having a center near 540 nm. Is realized.
  • the present invention realizes a phosphor thin film having the white fluorescence characteristic.
  • the present invention has the following features.
  • the present invention is a perovskite-type inorganic oxide phosphor, which is characterized in that a Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and has white fluorescent characteristics. It can be said that the amount of Bi added is mol% with respect to CaTiO 3 .
  • the ratio of Ca to Ti is 1: 1, and the amount of Bi added is atomic% when Ca or Ti is 100%.
  • the inorganic oxide phosphor of the present invention is characterized by having an emission spectrum in the entire wavelength range of 450 to 700 nm.
  • the present invention is a method for producing an inorganic oxide phosphor, wherein Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and fired at 900 ° C. to 1100 ° C. And Moreover, this invention relates to the light-emitting device, It has the inorganic oxide fluorescent substance of this invention, It is characterized by the above-mentioned.
  • the present invention is a white phosphor thin film of a perovskite oxide, characterized in that it is an epitaxial thin film in which Bi element is added in an amount of 0.1 atomic% to 0.4 atomic% to CaTiO 3 .
  • the epitaxial thin film can be produced by a manufacturing method described later.
  • the perovskite oxide phosphor thin film of the present invention has an emission spectrum with white fluorescence characteristics over the entire wavelength range of 450 to 700 nm.
  • the substrate used for the epitaxial thin film is preferably one of SrTiO 3 , LaAlO 3 , LaGaO 3 , MgO, and LaSrGaO 4 .
  • the present invention relates to a method for producing a white phosphor thin film of a perovskite oxide, wherein a perovskite oxide obtained by adding Bi element to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% is used as a target material.
  • a thin film is formed by epitaxial growth on a substrate. It can be said that the amount of Bi added is mol% with respect to CaTiO 3 .
  • the ratio of Ca to Ti is 1: 1, and the amount of Bi added is atomic% when Ca or Ti is 100%.
  • the thin film is preferably formed at a temperature of 600 ° C. or higher and 1000 ° C. or lower. Further, it is preferable to form the thin film in an oxygen pressure atmosphere of 200 mTorr or more and 1000 mTorr or less. Further, it is preferable to use a pulse laser deposition method.
  • the present invention is a light emitting device, and is characterized in that an epitaxial thin film of the present invention in which Bi element is added in an amount of 0.1 atomic% to 0.4 atomic% to CaTiO 3 is used as a phosphor thin film.
  • white fluorescence with excellent color rendering can be obtained by adding a Bi element to CaTiO 3 which is a perovskite oxide.
  • a white phosphor excellent in chemical stability can be obtained.
  • the addition amount of Bi element is 0.1 atomic% or more and 0.4 atomic% or less, a broad emission spectrum can be obtained in the entire wavelength range of 450 to 700 nm, and the emission intensity is large.
  • the emission intensity can be further improved in the wavelength region of 450 to 700 nm by firing at 900 ° C. or higher and 1100 ° C. or lower.
  • a white phosphor thin film with excellent color rendering can be obtained by adding Bi element to a CaTiO 3 thin film of a perovskite oxide.
  • a white phosphor thin film excellent in chemical stability can be obtained.
  • the addition amount of Bi element is 0.1 atomic% or more and 0.4 atomic% or less, a broad emission spectrum can be obtained in the entire wavelength range of 450 to 700 nm, and the emission intensity is large.
  • an epitaxial thin film having excellent fluorescence characteristics can be formed.
  • a perovskite oxide in which Bi element is added to CaTiO 3 by 0.1 atomic% or more and 0.4 atomic% or less can be epitaxially grown on the substrate, so that it is almost white.
  • a Bi-added CaTiO 3 thin film exhibiting fluorescence characteristics can be obtained. After the thin film is formed, excellent fluorescence characteristics can be obtained by performing a heat treatment at 900 ° C. to 1100 ° C. in the air.
  • the target material can be deposited with its stoichiometric composition by pulsed laser deposition. Further, by forming the thin film at a temperature of 600 ° C. or higher and 1000 ° C.
  • cluster growth becomes dominant, and the target material can be formed with its stoichiometric composition.
  • the target material can be formed with its stoichiometric composition.
  • a thin film in an oxygen pressure atmosphere of 200 mTorr or more and 1000 mTorr or less a broad emission spectrum can be obtained over the entire wavelength range of 450 to 700 nm.
  • Example 1 Diffuse reflection spectrum and (b) Excitation / emission spectrum of CaTiO 3 : Bi (0.2 at.%) Of Example 1 Diffuse reflection spectrum (upper) and excitation emission spectrum (lower) of CaTiO 3 : Bi added with 0, 0.1, 0.2, 0.3, 0.4, and 0.6 at.% Bi in Example 1 Luminescence intensity with respect to Bi concentration in Example 1 XRD pattern of CaTiO 3 : Bi (0.2 at.%) Baked at 900, 1000, 1100, 1200 ° C. in Example 2 Diffraction peaks on the (400), (242) and (004) planes of CaTiO 3 : Bi (0.2 at.%) Calcined at 900, 1000, 1100 and 1200 ° C. in Example 2.
  • Embodiments of the present invention will be described below.
  • the present inventors conducted the following investigation on the possibility of white fluorescence characteristics in bulk perovskite oxides. First, we searched for new perovskite phosphors under optimized synthesis conditions. CaTiO 3 , SrTiO 3 , and BaTiO 3 were used as the base material, and an element that could be expected as a luminescence center was added thereto. Table 1 shows the combinations of elements that can be expected as the base material and the emission center.
  • Luminescence was observed from a sample in which Bi was added to the combination of CaTiO 3 in Table 1. Luminescence could not be observed from other combinations.
  • CaTiO 3 uses CaCO 3 (99.99%), TiO 2 (99.99%), B 2 O 3 (99.9%), Bi 2 O 3 (99.9%), The procedure was as follows. CaCO 3 powder and TiO 2 powder were always dried in an oven at 120 ° C. to prevent moisture absorption. First, CaCO 3 and B 2 O 3 were dry-mixed and baked at 850 ° C. for 12 hours to synthesize CaB 2 O 4 serving as a flux (confirmed that there were no impurities by powder X-ray diffraction).
  • Bi 2 O 3 was dissolved in nitric acid, excess nitric acid was evaporated to bismuth nitrate, and this was dissolved in ethanol to prepare an ethanol solution of Bi (NO 3 ) 3 .
  • CaCO 3 , TiO 2 and CaB 2 O 4 were weighed at a molar ratio of 0.975: 1: 0.025 so that 1 g of CaTiO 3 : Bi was synthesized, and a Bi (NO 3 ) 3 ethanol solution was added to this.
  • Bi is added to CaTiO 3 so that it becomes 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mol%, and a few ml of ethanol is further added, and agate Wet mixing was performed until ethanol evaporated in the mortar.
  • This mixed powder was put into a platinum boat, heated to 1100 ° C. at 200 ° C./h, fired at that temperature for 6 h, and then cooled to room temperature to synthesize a CaTiO 3 : Bi powder sample.
  • the obtained powder was slightly agglomerated, but this was lightly pulverized to obtain a measurement sample.
  • FIG. 1 (a) and FIG. 1 (b) show diffuse reflection and excitation / emission spectra of CaTiO 3 : Bi (0.2 at.%), Respectively.
  • a broad emission was observed from 450 to 700 nm, which is a factor that appears white in the emission spectrum.
  • a peak A ′ at 335 nm and a shoulder B ′ at 365 nm were observed.
  • absorption due to the interband transition of CaTiO 3 was observed at 335 nm or less, and absorption due to the sp transition of Bi 3+ was observed near 365 nm.
  • FIG. 2 shows the diffuse reflection spectrum (upper stage) and excitation of the sample (CaTiO 3 : Bi) with Bi addition amounts of 0, 0.1, 0.2, 0.3, 0.4, and 0.6 at.%.
  • An emission spectrum (lower) is shown. Since the emission intensity of the sample to which Bi is added at 0.2 at.% Is maximum, the optimum amount of Bi added to CaTiO 3 is 0.2 at.%.
  • FIG. 3 shows the light emission intensity with respect to the Bi concentration. It can be seen that the emission intensity increases from 0 at.% To 0.2 at.% And then decreases. In addition, a sharp peak that was apparently emitted from CaTiO 3 : Pr was confirmed from the sample to which Bi was added at 0.6 at% (see FIG. 2). This is probably because Pr was mixed from the mortar during wet mixing or adhered between the cores, and mixed into the sample during firing.
  • the light emission of a phosphor using Bi is assumed to be a sp transition, and thus the light emission of the present invention is considered to be due to the Bi sp transition.
  • the wavelength of the peak A ′ in the excitation / emission spectrum shown in FIG. 1 corresponds to the band gap of CaTiO 3 , the energy of the electron-hole pair generated by the interband transition of the matrix moves to Bi and emits light. It is thought that there is.
  • the absorption near 365 nm in the reflection spectrum increases, and this absorption is considered to be due to the sp transition of Bi3 +. Therefore, the peak B ′ observed in the vicinity of 365 nm in the excitation / emission spectrum is considered to be due to the Bi3 + sp transition.
  • the amount of Bi added to CaTiO 3 is preferably 0.1 to 0.4 at.%. Further, 0.1 to 0.3 at.% Is more preferable because the emission intensity is high (FIGS. 2 and 3).
  • Example 2 firing conditions in the production of CaTiO 3 : Bi will be described.
  • the firing temperature was changed and examined.
  • a sample fired at 900, 1000, 1100, and 1200 ° C. with a firing time of 6 hours and an addition amount of Bi of 0.2 at.% was synthesized.
  • FIG. 4 shows an XRD pattern of CaTiO 3 : Bi (0.2 at.%) Fired at 900, 1000, 1100, and 1200 ° C. Only peaks attributed to CaTiO 3 were observed from the samples fired at 1100 ° C. and 1200 ° C. In addition to CaTiO 3 , peaks attributed to TiO 2 (rutile) were confirmed from the samples fired at 900 and 1000 ° C.
  • FIG. 5 shows an enlarged view of diffraction peaks on the (400), (242), and (004) planes.
  • the line width of the (242) plane in the synthesized sample is continuously narrowed from the firing temperature of 900 ° C. to 1200 ° C.
  • FIG. 6 shows a diffuse reflection spectrum (upper) and excitation / emission spectrum (lower) of CaTiO 3 : Bi (0.2 at.%) Fired at 900, 1000, 1100, and 1200 ° C.
  • the sample fired at 1200 ° C. had a marked decrease in emission intensity.
  • the shoulder B ′ near 365 nm as seen in the sample at 1100 ° C. was not seen. From the reflection spectrum, it was observed that the absorption due to the sp transition of Bi near 365 nm increased as the firing temperature was increased.
  • the firing conditions for producing the CaTiO 3 : Bi of the present invention are 900 ° C. or higher and 1100 ° C. or lower.
  • Examples 1 and 2 above examples of powder shape are shown, but the shape structure is not limited to powder, and it can be used in bulk shape, thin film shape and the like conventionally used as phosphors.
  • Example 3 an example of a thin film shape of a perovskite oxide in which Bi is added to CaTiO 3 will be described below.
  • a thin film was formed using a pulsed laser deposition method.
  • the pulse laser deposition method can form a thin film of about 500 nm in a short time (typical film formation time is 30 minutes), it is a film formation method expected to be applied to engineering. In addition, since the film can be formed in an oxygen stream, deterioration of electrical characteristics and fluorescence characteristics due to oxygen deficiency or the like can be extremely reduced during oxide thin film growth.
  • an ArF (wavelength: 193 nm) excimer laser is irradiated to a target material made of oxide in low-pressure oxygen of 1 Torr or less, and the target material is turned into plasma to form a plume, which counters the target material.
  • a superheated substrate is placed on the surface and a thin film is deposited. Cluster growth is dominant at a temperature of 1000 ° C. or lower, and the target material can be deposited with its stoichiometric composition.
  • a perovskite oxide in which Bi was added to CaTiO 3 was used as a polycrystalline target material, and the target material was irradiated with a pulse laser, and a thin film having the same composition as the target material was epitaxially grown on the substrate.
  • the polycrystalline target material is manufactured using the manufacturing method described in Examples 1 and 2. The distance between the substrate and the target was 32 mm. The laser irradiation frequency was 8 Hz, the film formation time was 30 minutes, and the film thickness was 300 nm. The laser energy is about 120 mJ.
  • a SrTiO 3 single crystal substrate polished so that the substrate surface was (001) was used as the substrate.
  • the crystal structure of SrTiO 3 is tetragonal and the lattice constant is 3.905 nm.
  • An oxide epitaxial thin film having excellent crystallinity can be grown because it has a lattice constant in the vicinity of the perovskite oxide obtained by adding Bi to CaTiO 3 of this example and has good lattice matching.
  • LaAlO 3 , LaGaO 3 , MgO, LaSrGaO 4 having good lattice matching can be used as the substrate.
  • Example 4 manufacturing conditions for manufacturing a white phosphor thin film made of CaTiO 3 to which Bi is added will be discussed below. The case where the best fluorescence characteristic was obtained and the addition amount of Bi was set to 0.2 atomic% was examined.
  • the film was formed under three conditions: the substrate temperature was 600 ° C., and the oxygen pressure during film formation was 10 mTorr, 100 mTorr, and 700 mTorr.
  • the substrate a SrTiO 3 (001) single crystal polishing substrate was used. X-ray diffraction was measured to investigate the crystal structure. As a result, it was confirmed that the (001) thin film was grown at all oxygen pressures.
  • FIG. 7 shows an X-ray diffraction pattern during growth at 600 ° C. and oxygen pressure of 700 mTorr as a typical example.
  • STO sub means SrTiO 3 substrate
  • BiCTO means Bi-added CaTiO 3 .
  • FIG. 8 shows fluorescence characteristics after film formation was performed under three conditions of a substrate temperature of 600 ° C. and an oxygen pressure of 10 mTorr, 100 mTorr, and 700 mTorr, and a heat treatment in the atmosphere at 1000 ° C. This is considered to be caused by the Bi3 + sp transition. From FIG. 8, it can be seen that a broad fluorescence characteristic cannot be obtained at an oxygen pressure of 10 mTorr or 100 mTorr, but a remarkable broad characteristic can be obtained at 700 mTorr.
  • the oxygen pressure condition is preferably 200 mTorr or more and 1000 Torr or less, and more preferably 400 mTorr or more and 1000 mTorr or less. Furthermore, the oxygen pressure conditions will be examined.
  • the pulse laser deposition method is a method in which a material having the same composition as the target material composition can be formed on the substrate by matching the distance between the substrate and the target and the mean free path of the target element particles.
  • the melting point of Bi element is 271 ° C., and a material having a low melting point temperature has a feature that it is easily scattered in plasma.
  • the mean free path of particles becomes long in low-pressure oxygen of 100 mTorr or less, only the Bi element in the Bi-added CaTiO 3 as the target material is scattered beyond the distance between the substrate and the target, and the Bi element is scattered in the thin film on the substrate. Lack. As a result, it is considered that fluorescence characteristics cannot be obtained.
  • the oxygen pressure is 700 mTorr, the mean free path and the distance between the substrate and the target match, so that the film adheres on the substrate with the composition of the target material.
  • a more preferable degree of vacuum (oxygen pressure) is 400 mTorr to 1000 mTorr.
  • a thin film can be formed at a substrate temperature of 600 ° C. or higher and 1000 ° C. or lower. This is because cluster growth is dominant at a temperature of 1000 ° C. or lower, and the target material can be deposited with its stoichiometric composition. In addition, at 500 degrees C or less, it becomes amorphous and a fluorescence characteristic is not acquired.
  • Examples 3 and 4 an example in which a film is formed by a pulse laser deposition method is shown.
  • a vapor phase growth method such as a sputtering method in addition to the pulse laser deposition method.
  • the thin film forming temperature, the oxygen pressure, and the heat treatment temperature are manufactured at the same temperature as the temperature shown in the embodiment, so that the same fluorescence characteristics as in the embodiment can be obtained.
  • the perovskite-type inorganic oxide phosphor of the present invention realizes a white fluorescent property with excellent color rendering properties and is excellent in chemical stability, and thus can be used for lighting equipment and the like.
  • the perovskite inorganic oxide phosphor thin film of the present invention realizes white fluorescent characteristics with excellent color rendering properties and is excellent in chemical stability. It can be used for luminescence devices.

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Abstract

Provided is a perovskite-type fluorescent oxide which has excellent chemical stability and the property of emitting white fluorescence and which is useful in thin-film electroluminescent devices for illuminators/light sources, displays, and the like. Also provided is a thin film of a fluorescent oxide. By adding Bi element to CaTiO3, which is a perovskite-type inorganic oxide, in an amount of 0.1-0.4 at.%, the property of emitting white fluorescence in which the fluorescent intensity is high throughout the whole wavelength range of 450-700 nm is imparted. This fluorescent material in any of particulate, bulk, and thin-film forms shows the white fluorescence properties. The fluorescent intensity can be further improved by burning, at 900-1,100ºC, the CaTiO3 to which Bi element has been added in the given amount. The thin film is obtained preferably by using a target comprising CaTiO3 containing Bi element to form a thin film by a pulsed laser deposition method at a given temperature in an atmosphere having a given oxygen pressure and by heat-treating the thin film in the air at a temperature of 900-1,100ºC.

Description

無機酸化物蛍光体及び白色蛍光体薄膜Inorganic oxide phosphor and white phosphor thin film
　本発明は、化学的安定性に優れ、演色性に優れた白色蛍光特性を有するペロブスカイト型酸化物の蛍光体及び白色蛍光体薄膜、それらの製造方法、並びに、蛍光体及び白色蛍光体薄膜を用いた発光装置に関する。 The present invention uses a phosphor of a perovskite oxide having excellent chemical stability and color rendering properties and a white phosphor thin film, a method for producing the same, and a phosphor and a white phosphor thin film. The present invention relates to a light emitting device.
　従来、主として利用されている照明器具は、白熱電球と蛍光灯である。蛍光灯は、水銀に低い蒸気圧で放電させることで効率良く２５４ｎｍおよび１８５ｎｍの紫外線を放出させることができる。該紫外線はガラス管内に塗布した蛍光体により白色光に変換される。蛍光灯は白熱電球に比べ発熱が極めて少なく同じ明るさを得るために必要な電力は数％である。しかし、近年になって欧州ではＲｏＨＳ指令により、電気電子機器関連装置・デバイスにおいて、鉛や水銀等の有害物質の使用を将来的に禁止する規制が発せられている。これによって、これまで利用してきた蛍光灯の使用が限定されることが予想され、新たな照明装置の開発が急務とされている。今後の照明としての候補は、白色ＬＥＤ、有機・無機ＥＬ等が挙げられるが、現時点で、何が先行するのかは決定されておらず、化学的安定性に優れた白色蛍光体の開発が求められている。 Conventionally, lighting fixtures mainly used are incandescent bulbs and fluorescent lamps. A fluorescent lamp can efficiently emit ultraviolet rays of 254 nm and 185 nm by discharging mercury at a low vapor pressure. The ultraviolet light is converted into white light by the phosphor applied in the glass tube. Fluorescent lamps generate much less heat than incandescent bulbs and require several percent of power to obtain the same brightness. In recent years, however, regulations have been issued in Europe to prohibit the use of harmful substances such as lead and mercury in electrical and electronic equipment related devices and devices in the future due to the RoHS directive. This is expected to limit the use of fluorescent lamps that have been used so far, and the development of new lighting devices is urgently needed. Candidates for future lighting include white LEDs, organic / inorganic EL, etc., but what has been determined at this time has not been determined, and the development of white phosphors with excellent chemical stability is required. It has been.
　従来、ペロブスカイト型構造の酸化物からなる蛍光体について研究開発が進められてきた（特許文献１～２、非特許文献１～５）。特許文献１には、多結晶体Ｓｎペロブスカイト酸化物系の蛍光特性が示されている。特許文献２には、アルカリ土類金属とジルコニウムの酸化物を蛍光母体とした、ペロブスカイト系材料の蛍光体で赤色、青色、緑色が実現されることが示されている。また、非特許文献１には、多結晶体ＡＳｎＯ3系ペロブスカイト構造においてＣａ、Ｓｒ、Ｂａで置換することで蛍光特性が得られることが示されている。非特許文献２には、多結晶体Ｓｎ系層状ペロブスカイト構造で青色蛍光が得られることが示されている。非特許文献３には、多結晶体層状ペロブスカイトＳｒn+1ＴｉnＯ3n+1系で赤色蛍光特性が示されている。非特許文献４には、多結晶体Ｐｒ原子置換（ＣａＳｒＢａ）ＴｉＯ3の赤色蛍光特性が示されている。非特許文献５には、ＣａＴｉＯ3：Ｐｒの赤色蛍光特性が示されている。 Conventionally, research and development have been conducted on phosphors made of oxides having a perovskite structure (Patent Documents 1 and 2, Non-Patent Documents 1 to 5). Patent Document 1 discloses fluorescence characteristics of a polycrystalline Sn perovskite oxide system. Patent Document 2 shows that red, blue, and green are realized with a phosphor of a perovskite-based material using an oxide of an alkaline earth metal and zirconium as a fluorescent matrix. Non-Patent Document 1 shows that fluorescence characteristics can be obtained by substituting Ca, Sr, and Ba in a polycrystalline ASnO 3 perovskite structure. Non-Patent Document 2 shows that blue fluorescence can be obtained with a polycrystalline Sn-based layered perovskite structure. Non-Patent Document 3 shows red fluorescence characteristics in a polycrystalline layered perovskite Sr n + 1 Ti n O 3n + 1 system. Non-Patent Document 4 shows the red fluorescence characteristic of polycrystalline Pr atom substitution (CaSrBa) TiO 3 . Non-Patent Document 5 shows the red fluorescence characteristic of CaTiO 3 : Pr.
　また白色蛍光体について先行技術を調査すると、特許文献３に白色蛍光体が示されている。特許文献３には、ａＭ1Ｏ・ｂＭ2 2Ｏ3・ｃＭ3Ｏ2（但し、Ｍ１はＢａ、Ｓｒ、Ｃａ、Ｍｇ及びＺｎからなる群から選ばれる１種以上の元素であり、Ｍ2はＡｌ、Ｓｃ、Ｇａ、Ｙ、Ｉｎ、Ｌａ、Ｇｄ及びＬｕからなる群から選ばれる１種以上の元素であり、Ｍ3はＳｉ、Ｔｉ、Ｇｅ、Ｚｒ、Ｓｎ及びＨｆからなる群から選ばれる１種以上の元素であり、ａは８以上１０以下、ｂは０.８以上１.２以下、ｃは５以上７以下の範囲の値である）で表される化合物に、付活剤として希土類元素、Ｍｎ及びＢｉからなる群より選ばれる１種以上の元素が含有されてなる蛍光体が記載されている。しかしながら、特許文献３の酸化物は、ペロブスカイト構造ではない。 Further, when the prior art is investigated for the white phosphor, Patent Document 3 shows the white phosphor. Patent Document 3 discloses aM 1 O.bM 2 2 O 3 .cM 3 O 2 (where M 1 is one or more elements selected from the group consisting of Ba, Sr, Ca, Mg, and Zn; 2 is one or more elements selected from the group consisting of Al, Sc, Ga, Y, In, La, Gd and Lu, and M 3 is selected from the group consisting of Si, Ti, Ge, Zr, Sn and Hf. An activator, wherein a is 8 or more and 10 or less, b is 0.8 or more and 1.2 or less, and c is 5 or more and 7 or less. Describes a phosphor containing one or more elements selected from the group consisting of rare earth elements, Mn and Bi. However, the oxide of Patent Document 3 does not have a perovskite structure.
　薄膜に関しては、近年、薄膜でディスプレイ作製の基礎となる赤色、緑色、青色の３原色の開発が進められている。ペロブスカイト型構造の酸化物薄膜からなる蛍光体については次のような研究開発が進められてきた（特許文献４、５。非特許文献６～８参照）。非特許文献６には、スズ系ペロブスカイト構造関連酸化物薄膜で、赤色、青色、緑色、白色の蛍光特性が紫外線励起で得られることが示されている。また、非特許文献８には、ジルコニア系ぺロブスカイト型酸化物薄膜で適切な希土類元素を添加することによって、赤色、青色、緑色蛍光が紫外線励起で出現することが示されている。また、本発明者等は、（ＣａＳｒ）ＴｉＯ3ぺロブスカイト型酸化物薄膜でＰｒを添加することによって赤色蛍光が紫外線励起で出現することを示した（非特許文献７参照）。 Regarding thin films, in recent years, the development of three primary colors of red, green, and blue, which are the basis of display production using thin films, has been promoted. The following research and development has been conducted on phosphors composed of oxide thin films having a perovskite structure (see Patent Documents 4 and 5; see Non-Patent Documents 6 to 8). Non-Patent Document 6 shows that red, blue, green, and white fluorescence characteristics can be obtained by ultraviolet excitation in a tin-based perovskite structure-related oxide thin film. Non-Patent Document 8 shows that red, blue, and green fluorescence appear by ultraviolet excitation by adding an appropriate rare earth element in a zirconia-based perovskite oxide thin film. In addition, the present inventors have shown that red fluorescence appears by ultraviolet excitation when Pr is added in a (CaSr) TiO 3 perovskite oxide thin film (see Non-Patent Document 7).
　本発明者等による特許文献４には、アルミニウム元素をＰｒ置換ＳｒＴｉＯ3ペロブスカイト型酸化物に添加した多結晶ターゲット材料を用い、パルスレーザー堆積法によって成膜した酸化物蛍光体エピタキシャル薄膜で優れた赤色の蛍光特性が得られることが示されている。具体的には、パルスレーザー堆積法によって、６００℃以上８００℃以下の温度でエピタキシャル成長により基板上に酸化物蛍光体エピタキシャル薄膜を形成することが示されている。 In Patent Document 4 by the present inventors, an excellent red phosphor oxide epitaxial thin film formed by a pulse laser deposition method using a polycrystalline target material in which an aluminum element is added to a Pr-substituted SrTiO 3 perovskite oxide. It has been shown that the fluorescence characteristics of Specifically, it is shown that an oxide phosphor epitaxial thin film is formed on a substrate by epitaxial growth at a temperature of 600 ° C. or higher and 800 ° C. or lower by a pulse laser deposition method.
　また、本発明者等による特許文献５には、スズ系ペロブスカイト構造関連酸化物薄膜で、赤色、青色、緑色、白色の蛍光特性が紫外線励起で得られることが示されている。具体的には、パルスレーザー堆積法によって、６００℃以上８００℃以下の温度でエピタキシャル成長により基板上に酸化物蛍光体エピタキシャル薄膜を形成することが示されている。 Also, Patent Document 5 by the present inventors shows that red, blue, green, and white fluorescence characteristics can be obtained by ultraviolet excitation in a tin-based perovskite structure-related oxide thin film. Specifically, it is shown that an oxide phosphor epitaxial thin film is formed on a substrate by epitaxial growth at a temperature of 600 ° C. or higher and 800 ° C. or lower by a pulse laser deposition method.
特開２００７－１４６１０２号公報JP 2007-146102 A 特開２００９－３５６２３号公報JP 2009-35623 A 特開２００７－７７３０７号公報JP 2007-77307 A 特開２００９－１５５３７６号公報JP 2009-155376 A 特開２００８－１９３１７号公報JP 2008-19317 A
　従来、有機ＥＬ、無機ＥＬ等多数の蛍光体が得られているが、酸化によって結晶性が低下し、蛍光特性の経年劣化が著しいという問題があった。 Conventionally, a large number of phosphors such as organic EL and inorganic EL have been obtained, but there is a problem that crystallinity is lowered due to oxidation, and aged deterioration of fluorescence characteristics is remarkable.
　化学的安定性に優れた白色蛍光体が求められているが、従来の結晶構造が単純なペロブスカイト型の無機酸化物においては、白色蛍光特性が実現できなかった。 Although white phosphors excellent in chemical stability are demanded, white fluorescent properties cannot be realized with conventional perovskite inorganic oxides having a simple crystal structure.
　また、薄膜に関して、酸化物多結晶体では、近年良好な蛍光体が得られ、薄膜でディスプレイ作製の基礎となる赤色、緑色、青色の３原色の開発が遂行されているが、白色蛍光体薄膜については、その演色性が十分ではないという問題があった。また、照明、液晶モニター用バックライト応用の際には、薄膜によるＥＬ開発が必要不可欠であり、酸化物白色蛍光体エピタキシャル薄膜の開発が望まれている。 In addition, regarding the thin film, the oxide polycrystal has been able to obtain a good phosphor in recent years, and the development of three primary colors of red, green, and blue, which are the basis of display production with the thin film, has been carried out. There was a problem that the color rendering was not sufficient. In addition, in the application of lighting and backlights for liquid crystal monitors, EL development using thin films is indispensable, and development of oxide white phosphor epitaxial thin films is desired.
　このように、化学的安定性に優れた白色蛍光体薄膜が求められているが、従来の結晶構造が単純なペロブスカイト型の無機酸化物薄膜においては、白色蛍光特性が実現できなかった。非特許文献６や特許文献５では、スズ系ペロブスカイト構造関連酸化物薄膜で、白色蛍光特性が示されているが、複数の鋭い発光スペクトルの相関によって白色を実現していたため演色性に乏しいという問題があった。 Thus, although a white phosphor thin film excellent in chemical stability is demanded, a white phosphor characteristic cannot be realized in a conventional perovskite-type inorganic oxide thin film having a simple crystal structure. Non-Patent Document 6 and Patent Document 5 show a white fluorescent property in a tin-based perovskite structure-related oxide thin film, but a problem of poor color rendering because white was realized by the correlation of a plurality of sharp emission spectra. was there.
　本発明は、これらの問題を解決しようとするものであり、ぺロブスカイト型酸化物を用いて、照明器具で使用可能な演色性の優れた白色蛍光特性を有する蛍光体を提供することを目的とする。また、白色蛍光特性を向上させる製造方法を提供することを目的とする。また、ペロブスカイト型酸化物を用いた発光装置を提供することを目的とする。 An object of the present invention is to solve these problems, and an object of the present invention is to provide a phosphor having a white fluorescent property with excellent color rendering property that can be used in a lighting fixture by using a perovskite oxide. To do. It is another object of the present invention to provide a manufacturing method that improves white fluorescent characteristics. It is another object of the present invention to provide a light emitting device using a perovskite oxide.
　また、本発明は、ぺロブスカイト型酸化物を用いて、紫外線励起により演色性の優れた白色蛍光特性を有する蛍光体エピタキシャル薄膜を提供することを目的とする。また、白色蛍光特性を向上させる白色蛍光体エピタキシャル薄膜の製造方法を提供することを目的とする。また、ペロブスカイト型酸化物白色蛍光体エピタキシャル薄膜を用いた発光装置を提供することを目的とする。 Another object of the present invention is to provide a phosphor epitaxial thin film having a white fluorescent property having excellent color rendering properties by ultraviolet excitation using a perovskite oxide. Moreover, it aims at providing the manufacturing method of the white fluorescent substance epitaxial thin film which improves a white fluorescence characteristic. It is another object of the present invention to provide a light emitting device using a perovskite oxide white phosphor epitaxial thin film.
　本発明は、ぺロブスカイト型酸化物として知られているＣａＴｉＯ3に原子番号８３番のビスマスＢｉを少量導入することによって、５４０ｎｍ近傍に中心を持つ波長領域でブロードな演色性に優れた白色蛍光特性を実現する。また、本発明は、該白色蛍光特性を備えた蛍光体薄膜を実現する。本発明は、前記目的を達成するために、以下の特徴を有する。 The present invention introduces a small amount of bismuth Bi having an atomic number of 83 into CaTiO 3 , which is known as a perovskite type oxide, and has a white fluorescent property with excellent broad color rendering in a wavelength region having a center near 540 nm. Is realized. In addition, the present invention realizes a phosphor thin film having the white fluorescence characteristic. In order to achieve the above object, the present invention has the following features.
　本発明は、ペロブスカイト型の無機酸化物蛍光体であって、ＣａＴｉＯ3にＢｉ元素を０.１原子％以上０.４原子％以下添加し、白色蛍光特性を有することを特徴とする。Ｂｉの添加量は、ＣａＴｉＯ3に対するモル％ともいえる。ＣａＴｉＯ3は、ＣａとＴｉの比は１：１で、Ｂｉの添加量は、ＣａまたはＴｉを１００％としたときの原子％である。また、本発明の無機酸化物蛍光体は、４５０から７００ｎｍの波長全域で発光スペクトルを有することを特徴とする。 The present invention is a perovskite-type inorganic oxide phosphor, which is characterized in that a Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and has white fluorescent characteristics. It can be said that the amount of Bi added is mol% with respect to CaTiO 3 . In CaTiO 3 , the ratio of Ca to Ti is 1: 1, and the amount of Bi added is atomic% when Ca or Ti is 100%. In addition, the inorganic oxide phosphor of the present invention is characterized by having an emission spectrum in the entire wavelength range of 450 to 700 nm.
　本発明は、無機酸化物蛍光体の製造方法であって、ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加し、９００℃以上１１００℃以下で焼成することを特徴とする。また、本発明は、発光装置に関し、本発明の無機酸化物蛍光体を有することを特徴とする。 The present invention is a method for producing an inorganic oxide phosphor, wherein Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and fired at 900 ° C. to 1100 ° C. And Moreover, this invention relates to the light-emitting device, It has the inorganic oxide fluorescent substance of this invention, It is characterized by the above-mentioned.
　本発明は、ペロブスカイト型酸化物の白色蛍光体薄膜であって、ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０．４原子％以下添加したエピタキシャル薄膜であることを特徴とする。該エピタキシャル薄膜は、後述の製造方法により作成することができる。本発明のペロブスカイト型酸化物蛍光体薄膜は、４５０から７００ｎｍの波長全域で白色蛍光特性の発光スペクトルを有する。本発明のペロブスカイト型酸化物の白色蛍光体薄膜において、エピタキシャル薄膜に用いる基板は、ＳｒＴｉＯ3、ＬａＡｌＯ3、ＬａＧａＯ3、ＭｇＯ、ＬａＳｒＧａＯ4のうちのいずれかの基板であることが好ましい。 The present invention is a white phosphor thin film of a perovskite oxide, characterized in that it is an epitaxial thin film in which Bi element is added in an amount of 0.1 atomic% to 0.4 atomic% to CaTiO 3 . The epitaxial thin film can be produced by a manufacturing method described later. The perovskite oxide phosphor thin film of the present invention has an emission spectrum with white fluorescence characteristics over the entire wavelength range of 450 to 700 nm. In the white phosphor thin film of the perovskite oxide of the present invention, the substrate used for the epitaxial thin film is preferably one of SrTiO 3 , LaAlO 3 , LaGaO 3 , MgO, and LaSrGaO 4 .
　本発明は、ペロブスカイト型酸化物の白色蛍光体薄膜の製造方法であって、ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加したペロブスカイト型酸化物をターゲット材料として、基板上に、エピタキシャル成長により薄膜を形成することを特徴とする。Ｂｉの添加量は、ＣａＴｉＯ3に対するモル％ともいえる。ＣａＴｉＯ3は、ＣａとＴｉの比は１：１で、Ｂｉの添加量は、ＣａまたはＴｉを１００％としたときの原子％である。本発明の白色蛍光体薄膜の製造方法においては、薄膜を形成後、大気中で、９００℃以上１１００℃以下の熱処理を行うことが好ましい。また、６００℃以上１０００℃以下の温度で薄膜を形成することが好ましい。また、２００ｍＴｏｒｒ以上１０００ｍＴｏｒｒ以下の酸素圧雰囲気で薄膜を形成することが好ましい。また、パルスレーザー堆積法を用いることが好ましい。 The present invention relates to a method for producing a white phosphor thin film of a perovskite oxide, wherein a perovskite oxide obtained by adding Bi element to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% is used as a target material. A thin film is formed by epitaxial growth on a substrate. It can be said that the amount of Bi added is mol% with respect to CaTiO 3 . In CaTiO 3 , the ratio of Ca to Ti is 1: 1, and the amount of Bi added is atomic% when Ca or Ti is 100%. In the method for producing a white phosphor thin film of the present invention, it is preferable to perform heat treatment at 900 ° C. or higher and 1100 ° C. or lower in the air after forming the thin film. In addition, the thin film is preferably formed at a temperature of 600 ° C. or higher and 1000 ° C. or lower. Further, it is preferable to form the thin film in an oxygen pressure atmosphere of 200 mTorr or more and 1000 mTorr or less. Further, it is preferable to use a pulse laser deposition method.
　本発明は、発光装置であって、本発明の、ＣａＴｉＯ3にＢｉ元素を０.１原子％以上０.４原子％以下添加したエピタキシャル薄膜を蛍光体薄膜として用いることを特徴とする。 The present invention is a light emitting device, and is characterized in that an epitaxial thin film of the present invention in which Bi element is added in an amount of 0.1 atomic% to 0.4 atomic% to CaTiO 3 is used as a phosphor thin film.
　本発明によれば、ぺロブスカイト型酸化物のＣａＴｉＯ3にＢｉ元素を添加することにより、演色性の優れた白色蛍光を得ることができる。ペロブスカイト型酸化物を用いることにより、化学的安定性に優れた白色蛍光体が得られる。特にＢｉ元素の添加量が０.１原子％以上０.４原子％以下であると、４５０から７００ｎｍの波長全域でブロードな発光スペクトルを得ることができ発光強度が大である。本発明に製造方法によれば、９００℃以上１１００℃以下で焼成することにより、４５０から７００ｎｍの波長域で発光強度をさらに向上させることできる。 According to the present invention, white fluorescence with excellent color rendering can be obtained by adding a Bi element to CaTiO 3 which is a perovskite oxide. By using the perovskite oxide, a white phosphor excellent in chemical stability can be obtained. In particular, when the addition amount of Bi element is 0.1 atomic% or more and 0.4 atomic% or less, a broad emission spectrum can be obtained in the entire wavelength range of 450 to 700 nm, and the emission intensity is large. According to the production method of the present invention, the emission intensity can be further improved in the wavelength region of 450 to 700 nm by firing at 900 ° C. or higher and 1100 ° C. or lower.
　本発明によれば、ぺロブスカイト型酸化物のＣａＴｉＯ3薄膜にＢｉ元素を添加することにより、演色性の優れた白色蛍光体薄膜を得ることができる。ペロブスカイト型酸化物薄膜を用いることにより、化学的安定性に優れた白色蛍光体薄膜が得られる。特にＢｉ元素の添加量が０.１原子％以上０.４原子％以下であると、４５０から７００ｎｍの波長全域でブロードな発光スペクトルを得ることができ発光強度が大である。基板として、ＳｒＴｉＯ3、ＬａＡｌＯ3、ＬａＧａＯ3、ＭｇＯ、ＬａＳｒＧａＯ4のうちのいずれかの基板を用いることにより、蛍光特性の優れたエピタキシャル薄膜を成膜することができる。 According to the present invention, a white phosphor thin film with excellent color rendering can be obtained by adding Bi element to a CaTiO 3 thin film of a perovskite oxide. By using a perovskite oxide thin film, a white phosphor thin film excellent in chemical stability can be obtained. In particular, when the addition amount of Bi element is 0.1 atomic% or more and 0.4 atomic% or less, a broad emission spectrum can be obtained in the entire wavelength range of 450 to 700 nm, and the emission intensity is large. By using any one of SrTiO 3 , LaAlO 3 , LaGaO 3 , MgO, and LaSrGaO 4 as the substrate, an epitaxial thin film having excellent fluorescence characteristics can be formed.
　本発明では、ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加したペロブスカイト型酸化物をターゲット材料として用いて、基板上にエピタキシャル成長させることができたので、白色に近い蛍光特性を示すＢｉ添加ＣａＴｉＯ3薄膜を得ることができる。薄膜を形成後、大気中で、９００℃以上１１００℃以下の熱処理を行うことにより、優れた蛍光特性が得られる。パルスレーザー堆積法により、ターゲット材料をその化学量論組成で成膜させることができる。また、６００℃以上１０００℃以下の温度で薄膜を形成することにより、クラスター成長が支配的となり、ターゲット材料をその化学量論組成で成膜することができる。また、２００ｍＴｏｒｒ以上１０００ｍＴｏｒｒ以下の酸素圧雰囲気で薄膜を形成することにより、４５０から７００ｎｍの波長全域でブロードな発光スペクトルを得ることができる。 In the present invention, a perovskite oxide in which Bi element is added to CaTiO 3 by 0.1 atomic% or more and 0.4 atomic% or less can be epitaxially grown on the substrate, so that it is almost white. A Bi-added CaTiO 3 thin film exhibiting fluorescence characteristics can be obtained. After the thin film is formed, excellent fluorescence characteristics can be obtained by performing a heat treatment at 900 ° C. to 1100 ° C. in the air. The target material can be deposited with its stoichiometric composition by pulsed laser deposition. Further, by forming the thin film at a temperature of 600 ° C. or higher and 1000 ° C. or lower, cluster growth becomes dominant, and the target material can be formed with its stoichiometric composition. Further, by forming a thin film in an oxygen pressure atmosphere of 200 mTorr or more and 1000 mTorr or less, a broad emission spectrum can be obtained over the entire wavelength range of 450 to 700 nm.
実施例１のＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の（ａ）拡散反射スペクトルと（ｂ）励起・発光スペクトル(A) Diffuse reflection spectrum and (b) Excitation / emission spectrum of CaTiO 3 : Bi (0.2 at.%) Of Example 1 実施例１におけるＢｉを０、０.１、０.２、０.３、０.４、０.６ａｔ.％添加したＣａＴｉＯ3：Ｂｉの拡散反射スペクトル（上段）と励起発光スペクトル（下段）Diffuse reflection spectrum (upper) and excitation emission spectrum (lower) of CaTiO 3 : Bi added with 0, 0.1, 0.2, 0.3, 0.4, and 0.6 at.% Bi in Example 1 実施例１におけるＢｉの濃度に対する発光強度Luminescence intensity with respect to Bi concentration in Example 1 実施例２における９００、１０００、１１００、１２００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）のＸＲＤパターンXRD pattern of CaTiO 3 : Bi (0.2 at.%) Baked at 900, 1000, 1100, 1200 ° C. in Example 2 実施例２における９００、１０００、１１００、１２００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の（４００）、（２４２）、（００４）面における回折ピークDiffraction peaks on the (400), (242) and (004) planes of CaTiO 3 : Bi (0.2 at.%) Calcined at 900, 1000, 1100 and 1200 ° C. in Example 2. 実施例２における９００、１０００、１１００、１２００℃で焼成したＣａＴｉＯ３：Ｂｉ（０.２ａｔ.％）の拡散反射スペクトル（上段）と励起・発光スペクトル（下段）Diffuse reflection spectrum (upper) and excitation / emission spectrum (lower) of CaTiO 3 : Bi (0.2 at.%) Calcined at 900, 1000, 1100, 1200 ° C. in Example 2 実施例４における酸素圧７００ｍＴｏｒｒ６００℃で成長した時のＸ線回折パターンX-ray diffraction pattern when grown at an oxygen pressure of 700 mTorr 600 ° C. in Example 4 実施例４における、酸素圧を１０ｍＴｏｒｒ、１００ｍＴｏｒｒ、７００ｍＴｏｒｒの３種の条件で成膜をしたときの蛍光特性Fluorescence characteristics when film was formed under three conditions of Example 4 with an oxygen pressure of 10 mTorr, 100 mTorr, and 700 mTorr
　本発明の実施の形態について、以下説明する。本発明者等は、バルク状のペロブスカイト型酸化物において、白色蛍光特性の可能性について次の調査を行った。まず、最適化された合成条件でペロブスカイト型新規蛍光体の探索を行った。母体にはＣａＴｉＯ3、ＳｒＴｉＯ3、ＢａＴｉＯ3を用いて、これに発光中心として期待できる元素を添加した。調査した母体と発光中心として期待できる元素の組み合わせを表１に示す。 Embodiments of the present invention will be described below. The present inventors conducted the following investigation on the possibility of white fluorescence characteristics in bulk perovskite oxides. First, we searched for new perovskite phosphors under optimized synthesis conditions. CaTiO 3 , SrTiO 3 , and BaTiO 3 were used as the base material, and an element that could be expected as a luminescence center was added thereto. Table 1 shows the combinations of elements that can be expected as the base material and the emission center.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の組み合わせのＣａＴｉＯ3にＢｉを添加した試料から発光が観測された。その他の組み合わせからは、発光が観測できなかった。 Luminescence was observed from a sample in which Bi was added to the combination of CaTiO 3 in Table 1. Luminescence could not be observed from other combinations.
（実施例１）
　本発明の実施例１について、図及び表を参照して以下詳しく説明する。 Example 1
Embodiment 1 of the present invention will be described in detail below with reference to the drawings and tables.
　ＣａＴｉＯ3にＢｉを添加した試料の製造について説明する。ＣａＴｉＯ3：Ｂｉは、ＣａＣＯ3（９９.９９％）、ＴｉＯ2（９９.９９％）、Ｂ2Ｏ3（９９.９％）、Ｂｉ2Ｏ3（９９.９％）を用いて、以下の手順で合成した。ＣａＣＯ3粉末とＴｉＯ2粉末は吸湿を防ぐため、１２０℃のオーブンで常時乾燥させた。まず、ＣａＣＯ3とＢ2Ｏ3を乾式混合し、８５０℃で１２ｈ焼成することで、フラックスとなるＣａＢ2Ｏ4を合成した（粉末Ｘ線回折で不純物がないことを確かめた）。次に、Ｂｉ2Ｏ3を硝酸で溶解し、過剰な硝酸を蒸発させて硝酸ビスマスとした後、これをエタノールに溶解してＢｉ（ＮＯ3）3のエタノール溶液を作製した。ＣａＴｉＯ3：Ｂｉが１ｇ合成されるように、ＣａＣＯ3、ＴｉＯ2、ＣａＢ2Ｏ4を０.９７５：１：０.０２５のモル比で秤量し、これにＢｉ（ＮＯ3）3エタノール溶液をＣａＴｉＯ3に対してＢｉが、０、０.１、０.２、０.３、０.４、０.５、０.６モル％になるように加え、さらにエタノールを数ｍｌ加えて、メノウ乳鉢中でエタノールが蒸発するまで湿式混合した。この混合粉末を白金ボートに入れ、２００℃／ｈで１１００℃まで昇温し、その温度で６ｈ焼成した後、室温まで炉冷することによって、ＣａＴｉＯ3：Ｂｉ粉末試料を合成した。得られた粉末は少し凝集しているが、これを軽く粉砕し、測定試料とした。 The production of a sample obtained by adding Bi to CaTiO 3 will be described. CaTiO 3 : Bi uses CaCO 3 (99.99%), TiO 2 (99.99%), B 2 O 3 (99.9%), Bi 2 O 3 (99.9%), The procedure was as follows. CaCO 3 powder and TiO 2 powder were always dried in an oven at 120 ° C. to prevent moisture absorption. First, CaCO 3 and B 2 O 3 were dry-mixed and baked at 850 ° C. for 12 hours to synthesize CaB 2 O 4 serving as a flux (confirmed that there were no impurities by powder X-ray diffraction). Next, Bi 2 O 3 was dissolved in nitric acid, excess nitric acid was evaporated to bismuth nitrate, and this was dissolved in ethanol to prepare an ethanol solution of Bi (NO 3 ) 3 . CaCO 3 , TiO 2 and CaB 2 O 4 were weighed at a molar ratio of 0.975: 1: 0.025 so that 1 g of CaTiO 3 : Bi was synthesized, and a Bi (NO 3 ) 3 ethanol solution was added to this. Bi is added to CaTiO 3 so that it becomes 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 mol%, and a few ml of ethanol is further added, and agate Wet mixing was performed until ethanol evaporated in the mortar. This mixed powder was put into a platinum boat, heated to 1100 ° C. at 200 ° C./h, fired at that temperature for 6 h, and then cooled to room temperature to synthesize a CaTiO 3 : Bi powder sample. The obtained powder was slightly agglomerated, but this was lightly pulverized to obtain a measurement sample.
　ＣａＴｉＯ3：Ｂｉの詳細な発光特性について以下調べた。まず、紫外線（３３０ｎｍ）をＣａＴｉＯ3：Ｂｉに照射した時、白色の発光を示すことが分かった。図１（ａ）と図１（ｂ）に、ＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の拡散反射と励起・発光スペクトルをそれぞれ示す。発光スペクトルに白色に見える要因の４５０から７００ｎｍにブロードな発光が観測された。励起スペクトルからは３３５ｎｍにピークＡ’、３６５ｎｍに肩Ｂ’が観測された。反射スペクトルからは３３５ｎｍ以下にＣａＴｉＯ3のバンド間遷移による吸収と、３６５ｎｍ付近にＢｉ３＋のｓ－ｐ遷移による吸収が観測された。 The detailed light emission characteristics of CaTiO 3 : Bi were examined below. First, it was found that white light was emitted when CaTiO 3 : Bi was irradiated with ultraviolet rays (330 nm). FIG. 1 (a) and FIG. 1 (b) show diffuse reflection and excitation / emission spectra of CaTiO 3 : Bi (0.2 at.%), Respectively. A broad emission was observed from 450 to 700 nm, which is a factor that appears white in the emission spectrum. From the excitation spectrum, a peak A ′ at 335 nm and a shoulder B ′ at 365 nm were observed. From the reflection spectrum, absorption due to the interband transition of CaTiO 3 was observed at 335 nm or less, and absorption due to the sp transition of Bi 3+ was observed near 365 nm.
　次に、発光強度のＢｉ濃度依存性について説明する。Ｂｉの添加量を、０、０.１、０.２、０.３、０.４、０.６ａｔ.％とした試料を合成し、Ｂｉの最適な組成比を調べた。またＢｉを添加することによりＣａＴｉＯ3の格子定数が変化するか粉末Ｘ線回折実験により得た回折ピーク位置を比較し調べた。表２に、Ｂｉを０ａｔ.％添加して合成した試料と０.６ａｔ.％添加して合成した試料の格子定数を示す。なお、括弧内の数値は最後の桁の数値の誤差を示す。 Next, the Bi concentration dependency of the emission intensity will be described. Samples with Bi addition amounts of 0, 0.1, 0.2, 0.3, 0.4, and 0.6 at.% Were synthesized, and the optimum composition ratio of Bi was examined. In addition, the diffraction peak positions obtained by powder X-ray diffraction experiments were compared to investigate whether the lattice constant of CaTiO 3 was changed by adding Bi. Table 2 shows the lattice constants of a sample synthesized by adding Bi at 0 at.% And a sample synthesized by adding 0.6 at.%. In addition, the numerical value in parenthesis shows the error of the numerical value of the last digit.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２において、０ａｔ.％添加して合成した試料と０.６ａｔ.％添加して合成した試料の格子定数は、誤差内で一致したことから、０.６ａｔ.％の添加では格子定数の変化は観測されないことが分かる。 In Table 2, the lattice constants of the sample synthesized with the addition of 0 at.% And the sample synthesized with the addition of 0.6 at.% Matched within the error. Is not observed.
　図２に、Ｂｉの添加量を０、０.１、０.２、０.３、０.４、０.６ａｔ.％とした試料（ＣａＴｉＯ3：Ｂｉ）の拡散反射スペクトル（上段）と励起発光スペクトル（下段）を示す。Ｂｉを０.２ａｔ.％添加した試料の発光強度が最大であることから、ＣａＴｉＯ3に対するＢｉの最適な添加量は０.２ａｔ.％である。 FIG. 2 shows the diffuse reflection spectrum (upper stage) and excitation of the sample (CaTiO 3 : Bi) with Bi addition amounts of 0, 0.1, 0.2, 0.3, 0.4, and 0.6 at.%. An emission spectrum (lower) is shown. Since the emission intensity of the sample to which Bi is added at 0.2 at.% Is maximum, the optimum amount of Bi added to CaTiO 3 is 0.2 at.%.
　図３に、Ｂｉの濃度に対する発光強度を示す。発光強度は０ａｔ.％から０.２ａｔ.％まで増大しそれ以降減少していることがわかる。またＢｉを０.６ａｔ.％添加した試料から明らかにＣａＴｉＯ3：Ｐｒの発光と思われる先鋭なピークが確認された（図２参照）。これはＰｒが湿式混合の際乳鉢から混入したか炉心間に付着していており、焼成の際試料に混入したものと考えられる。 FIG. 3 shows the light emission intensity with respect to the Bi concentration. It can be seen that the emission intensity increases from 0 at.% To 0.2 at.% And then decreases. In addition, a sharp peak that was apparently emitted from CaTiO 3 : Pr was confirmed from the sample to which Bi was added at 0.6 at% (see FIG. 2). This is probably because Pr was mixed from the mortar during wet mixing or adhered between the cores, and mixed into the sample during firing.
　本実施例によれば、ＣａＴｉＯ3にＢｉを添加することにより、白色蛍光体としての特性を有することがわかる。一般にＢｉを用いた蛍光体の発光はｓ－ｐ遷移とされているため、本発明の発光は、Ｂｉのｓ－ｐ遷移によるものと考えられる。図１に示した励起・発光スペクトルにおけるピークＡ’の波長はＣａＴｉＯ3のバンドギャップに相当することから、母体のバンド間遷移により生成した電子正孔対のエネルギーがＢｉに移動して発光しているものと考えられる。Ｂｉの添加濃度を増やしていくと反射スペクトルにおける３６５ｎｍ付近の吸収が大きくなったことから、この吸収はＢｉ３＋のｓ－ｐ遷移によるものと考えられる。したがって、励起・発光スペクトルにおいて３６５ｎｍ付近に観測されたピークＢ’はＢｉ３＋のｓ－ｐ遷移によるものと考えられる。 According to this embodiment, by adding Bi to the CaTiO 3, it is found to have the characteristics of a white phosphor. In general, the light emission of a phosphor using Bi is assumed to be a sp transition, and thus the light emission of the present invention is considered to be due to the Bi sp transition. Since the wavelength of the peak A ′ in the excitation / emission spectrum shown in FIG. 1 corresponds to the band gap of CaTiO 3 , the energy of the electron-hole pair generated by the interband transition of the matrix moves to Bi and emits light. It is thought that there is. As the additive concentration of Bi increases, the absorption near 365 nm in the reflection spectrum increases, and this absorption is considered to be due to the sp transition of Bi3 +. Therefore, the peak B ′ observed in the vicinity of 365 nm in the excitation / emission spectrum is considered to be due to the Bi3 + sp transition.
　以上のことから、本発明において、ＣａＴｉＯ3に対するＢｉの添加量は、０.１～０.４ａｔ.％が好ましい。さらに、０.１～０.３ａｔ.％であれば、発光強度が大であるので（図２、３）より好ましい。 From the above, in the present invention, the amount of Bi added to CaTiO 3 is preferably 0.1 to 0.4 at.%. Further, 0.1 to 0.3 at.% Is more preferable because the emission intensity is high (FIGS. 2 and 3).
（実施例２）
　本実施例では、ＣａＴｉＯ3：Ｂｉの製造における焼成条件について説明する。実施例１で示した同じ条件の製造方法において、焼成温度を変えて調べた。焼成時間６ｈ、Ｂｉの添加量を０.２ａｔ.％とし、９００、１０００、１１００、１２００℃で焼成した試料を合成した。 (Example 2)
In this example, firing conditions in the production of CaTiO 3 : Bi will be described. In the manufacturing method of the same conditions shown in Example 1, the firing temperature was changed and examined. A sample fired at 900, 1000, 1100, and 1200 ° C. with a firing time of 6 hours and an addition amount of Bi of 0.2 at.% Was synthesized.
　図４に、９００、１０００、１１００、１２００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）のＸＲＤパターンを示す。１１００℃と１２００℃で焼成した試料からはＣａＴｉＯ3に帰属するピークのみ観測された。９００、１０００℃で焼成した試料からはＣａＴｉＯ3のほかにＴｉＯ2（ｒｕｔｉｌｅ）に帰属するピークが確認された。 FIG. 4 shows an XRD pattern of CaTiO 3 : Bi (0.2 at.%) Fired at 900, 1000, 1100, and 1200 ° C. Only peaks attributed to CaTiO 3 were observed from the samples fired at 1100 ° C. and 1200 ° C. In addition to CaTiO 3 , peaks attributed to TiO 2 (rutile) were confirmed from the samples fired at 900 and 1000 ° C.
　図５に、（４００）、（２４２）、（００４）面の回折ピークの拡大図を示す。合成した試料における（２４２）面の線幅は、焼成温度９００℃から１２００℃まで連続的に狭くなっている。 FIG. 5 shows an enlarged view of diffraction peaks on the (400), (242), and (004) planes. The line width of the (242) plane in the synthesized sample is continuously narrowed from the firing temperature of 900 ° C. to 1200 ° C.
　図６に、９００、１０００、１１００、１２００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の拡散反射スペクトル（上段）と励起・発光スペクトル（下段）を示す。１２００℃で焼成した試料は発光強度が著しく下がった。９００℃と１０００℃で焼成した試料の発光スペクトルからは、１１００℃の試料で見られたような３６５ｎｍ付近の肩Ｂ’は見られなかった。反射スペクトルからは、焼成温度を高くするにつれ３６５ｎｍ付近のＢｉのｓ－ｐ遷移による吸収が大きくなっていることが観測された。 FIG. 6 shows a diffuse reflection spectrum (upper) and excitation / emission spectrum (lower) of CaTiO 3 : Bi (0.2 at.%) Fired at 900, 1000, 1100, and 1200 ° C. The sample fired at 1200 ° C. had a marked decrease in emission intensity. From the emission spectra of the samples fired at 900 ° C. and 1000 ° C., the shoulder B ′ near 365 nm as seen in the sample at 1100 ° C. was not seen. From the reflection spectrum, it was observed that the absorption due to the sp transition of Bi near 365 nm increased as the firing temperature was increased.
　１２００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の発光強度は、９００、１０００、１１００℃で焼成したＣａＴｉＯ3：Ｂｉ（０.２ａｔ.％）の発光強度より大幅に低かった。この原因として、まず、低融点のＢｉ2Ｏ3が焼成中に蒸発したことが考えられる。しかし、１２００℃で焼成したＣａＴｉＯ3：Ｂｉの反射スペクトルにおける３６５ｎｍ付近のＢｉの吸収は消失していないことから、Ｂｉは蒸発していないと考えられる。別の原因として、１２００℃で焼成したＣａＴｉＯ3：Ｂｉに酸素欠損が生じ、この酸素欠損が照射光や発光を吸収し、発光効率が低下したことが考えられる。実際に、１２００℃で焼成したＣａＴｉＯ3：Ｂｉの反射スペクトルでは可視領域の反射率が低下し、新たな吸収が現れている。 The luminescence intensity of CaTiO 3 : Bi (0.2 at.%) Fired at 1200 ° C. was significantly lower than that of CaTiO 3 : Bi (0.2 at.%) Baked at 900, 1000 and 1100 ° C. As a cause of this, it is conceivable that Bi 2 O 3 having a low melting point evaporates during firing. However, since the absorption of Bi near 365 nm in the reflection spectrum of CaTiO 3 : Bi baked at 1200 ° C. has not disappeared, it is considered that Bi is not evaporated. As another cause, it is considered that oxygen deficiency occurred in CaTiO 3 : Bi baked at 1200 ° C., and this oxygen deficiency absorbed irradiation light and light emission, resulting in a decrease in light emission efficiency. Actually, in the reflection spectrum of CaTiO 3 : Bi baked at 1200 ° C., the reflectance in the visible region is lowered and new absorption appears.
　以上のことから、本発明のＣａＴｉＯ3：Ｂｉを製造する際の、焼成条件は、９００℃以上１１００℃以下であることが好ましい。 From the above, it is preferable that the firing conditions for producing the CaTiO 3 : Bi of the present invention are 900 ° C. or higher and 1100 ° C. or lower.
　上記実施例１、２では、粉末形状の例を示したが、その形状構造は粉末に限定されず、従来、蛍光体として用いられているバルク状、薄膜状等で用いることができる。 In Examples 1 and 2 above, examples of powder shape are shown, but the shape structure is not limited to powder, and it can be used in bulk shape, thin film shape and the like conventionally used as phosphors.
（実施例３）
　本実施例では、ＣａＴｉＯ3にＢｉを添加したペロブスカイト型酸化物の、薄膜形状の例について、以下説明する。本実施例では、パルスレーザー堆積法を用いて薄膜を作製した。 (Example 3)
In this example, an example of a thin film shape of a perovskite oxide in which Bi is added to CaTiO 3 will be described below. In this example, a thin film was formed using a pulsed laser deposition method.
　パルスレーザー堆積法は短時間（典型的成膜時間は３０分）で５００ｎｍ程度の薄膜を形成することができることから、工学的応用が期待されている成膜方法である。また、酸素気流中で成膜することができるため、酸化物薄膜成長時には酸素欠損等による電気的特性、蛍光特性の劣化を極めて少なくすることができる。パルスレーザー堆積法では、１Ｔｏｒｒ以下の低圧酸素中で、酸化物からなるターゲット材料にＡｒＦ（波長１９３ｎｍ）のエキシマレーザーを照射し、ターゲット材料をプラズマ化させプルームを形成し、そのターゲット材料に対抗した面に過熱した基板を配置し、薄膜を堆積させる。１０００℃以下の温度ではクラスター成長が支配的であり、ターゲット材料をその化学量論組成で成膜させることができることを特徴とする。 Since the pulse laser deposition method can form a thin film of about 500 nm in a short time (typical film formation time is 30 minutes), it is a film formation method expected to be applied to engineering. In addition, since the film can be formed in an oxygen stream, deterioration of electrical characteristics and fluorescence characteristics due to oxygen deficiency or the like can be extremely reduced during oxide thin film growth. In the pulsed laser deposition method, an ArF (wavelength: 193 nm) excimer laser is irradiated to a target material made of oxide in low-pressure oxygen of 1 Torr or less, and the target material is turned into plasma to form a plume, which counters the target material. A superheated substrate is placed on the surface and a thin film is deposited. Cluster growth is dominant at a temperature of 1000 ° C. or lower, and the target material can be deposited with its stoichiometric composition.
　本実施例では、多結晶ターゲット材料として、ＣａＴｉＯ３にＢｉを添加したペロブスカイト型酸化物を用い、パルスレーザーを該ターゲット材料に照射し、ターゲット材料と同じ組成の薄膜を基板上にエピタキシャル成長させた。該多結晶ターゲット材料は、実施例１、２に記載した製造方法を用いて製造したものである。基板とターゲット間距離は３２ｍｍとした。レーザー照射周波数は８Ｈｚであり、成膜時間は３０分で、膜厚３００ｎｍであった。レーザーエネルギーは約１２０ｍＪである。 In this example, a perovskite oxide in which Bi was added to CaTiO 3 was used as a polycrystalline target material, and the target material was irradiated with a pulse laser, and a thin film having the same composition as the target material was epitaxially grown on the substrate. The polycrystalline target material is manufactured using the manufacturing method described in Examples 1 and 2. The distance between the substrate and the target was 32 mm. The laser irradiation frequency was 8 Hz, the film formation time was 30 minutes, and the film thickness was 300 nm. The laser energy is about 120 mJ.
　基板は、基板面が（００１）となるよう研磨したＳｒＴｉＯ3単結晶基板を用いた。ＳｒＴｉＯ3の結晶構造は正方晶であり、格子定数は３.９０５ｎｍである。本実施例のＣａＴｉＯ3にＢｉを添加したペロブスカイト型酸化物の近傍の格子定数を持ち、その格子整合性が良いため、結晶性の優れた酸化物エピタキシャル薄膜を成長させることができた。 As the substrate, a SrTiO 3 single crystal substrate polished so that the substrate surface was (001) was used. The crystal structure of SrTiO 3 is tetragonal and the lattice constant is 3.905 nm. An oxide epitaxial thin film having excellent crystallinity can be grown because it has a lattice constant in the vicinity of the perovskite oxide obtained by adding Bi to CaTiO 3 of this example and has good lattice matching.
　基板として、ＳｒＴｉＯ3基板の他に、格子整合性のよい、ＬａＡｌＯ3、ＬａＧａＯ3、ＭｇＯ、ＬａＳｒＧａＯ4を用いることができる。 In addition to the SrTiO 3 substrate, LaAlO 3 , LaGaO 3 , MgO, LaSrGaO 4 having good lattice matching can be used as the substrate.
（実施例４）
　本実施例においては、Ｂｉを添加したＣａＴｉＯ3からなる白色蛍光体薄膜を製造する製造条件について以下検討する。最も良い蛍光特性が得られた、Ｂｉの添加量を０.２原子％とした場合について調べた。 Example 4
In this example, manufacturing conditions for manufacturing a white phosphor thin film made of CaTiO 3 to which Bi is added will be discussed below. The case where the best fluorescence characteristic was obtained and the addition amount of Bi was set to 0.2 atomic% was examined.
　パルスレーザー堆積法において、基板温度は６００℃で，成膜時の酸素圧は１０ｍＴｏｒｒ，１００ｍＴｏｒｒ，７００ｍＴｏｒｒの３種の条件で成膜を行った。基板は、ＳｒＴｉＯ3（００１）単結晶研磨基板を用いた。結晶構造を調べるためＸ線回折を測定した。その結果、全ての酸素圧で（００１）薄膜が成長していることが確認された。図７に、典型的例として６００℃、酸素圧７００ｍＴｏｒｒ成長時のＸ線回折パターンを示す。図中、ＳＴＯsubはＳｒＴｉＯ3基板を意味し、ＢｉＣＴＯは、Ｂｉ添加ＣａＴｉＯ3を意味する。（００ｌ）で指数付けされるピーク以外の出現が確認されず、不純物ピークは確認されていない。図７中の枠内に拡大表示したように、（００２）のピークは基板のピークと薄膜のピークに明確に分離していることが分かり、基板ＳＴＯよりも薄膜ＢｉＣＴＯの方が、格子定数が小さいため高角側にピークが出現している。この結果、ＳｒＴｉＯ3（００２）／ＣａＴｉＯ3：Ｂｉ（００２）の格子ミスマッチは２.５％程度であるが、エピタキシャル成長が達成されていることが分かる。 In the pulse laser deposition method, the film was formed under three conditions: the substrate temperature was 600 ° C., and the oxygen pressure during film formation was 10 mTorr, 100 mTorr, and 700 mTorr. As the substrate, a SrTiO 3 (001) single crystal polishing substrate was used. X-ray diffraction was measured to investigate the crystal structure. As a result, it was confirmed that the (001) thin film was grown at all oxygen pressures. FIG. 7 shows an X-ray diffraction pattern during growth at 600 ° C. and oxygen pressure of 700 mTorr as a typical example. In the figure, STO sub means SrTiO 3 substrate, and BiCTO means Bi-added CaTiO 3 . Appearance other than the peak indexed by (00l) is not confirmed, and no impurity peak is confirmed. As shown in the enlarged frame in FIG. 7, it can be seen that the peak of (002) is clearly separated into the peak of the substrate and the peak of the thin film, and the thin film BiCTO has a lattice constant higher than that of the substrate STO. Since it is small, a peak appears on the high angle side. As a result, the lattice mismatch of SrTiO 3 (002) / CaTiO 3 : Bi (002) is about 2.5%, but it can be seen that the epitaxial growth is achieved.
　薄膜成長直後試料の蛍光特性を調べたところ、明確な蛍光特性は得られなかった。しかし、それらに対し大気中１０００℃で熱処理を行ったところ、７００ｍＴｏｒｒで成長した試料において紫外線波長３３０ｎｍで励起したところ５４０ｎｍ付近にブロードなピークが観測された。図８に、基板温度６００℃で酸素圧を１０ｍＴｏｒｒ、１００ｍＴｏｒｒ、７００ｍＴｏｒｒの３種の条件で成膜を行い、１０００℃で大気中熱処理を行った後の蛍光特性を示す。これはＢｉ３＋のｓ－ｐ遷移に起因するものと考えられる。図８から、酸素圧１０ｍＴｏｒｒや１００ｍＴｏｒｒではブロードな蛍光特性は得られないものの、７００ｍＴｏｒｒでは顕著なブロードな特性が得られることが分かる。 When the fluorescence characteristics of the sample were examined immediately after the growth of the thin film, no clear fluorescence characteristics were obtained. However, when they were heat-treated at 1000 ° C. in the atmosphere, a broad peak was observed around 540 nm when excited at an ultraviolet wavelength of 330 nm in a sample grown at 700 mTorr. FIG. 8 shows fluorescence characteristics after film formation was performed under three conditions of a substrate temperature of 600 ° C. and an oxygen pressure of 10 mTorr, 100 mTorr, and 700 mTorr, and a heat treatment in the atmosphere at 1000 ° C. This is considered to be caused by the Bi3 + sp transition. From FIG. 8, it can be seen that a broad fluorescence characteristic cannot be obtained at an oxygen pressure of 10 mTorr or 100 mTorr, but a remarkable broad characteristic can be obtained at 700 mTorr.
　図８から、酸素圧の条件は、２００ｍＴｏｒｒ以上１０００Ｔｏｒｒ以下が好ましく、４００ｍＴｏｒｒ以上１０００ｍＴｏｒｒ以下がより好ましい。さらに、酸素圧の条件について検討する。パルスレーザー堆積法は、基板－ターゲット間距離とターゲットの元素粒子の平均自由行程がマッチすることで、ターゲット材料組成と同一の材料を基板上に成膜することができる方法である。Ｂｉ元素の融点は２７１℃であり、融点温度の低い材料は、プラズマ中で飛散しやすい特長を持つ。１００ｍＴｏｒｒ以下の低圧酸素中では粒子の平均自由行程が長くなるため、基板－ターゲット間距離以上にターゲット材料であるＢｉ添加ＣａＴｉＯ3中のＢｉ元素のみが飛散し、基板上の薄膜にはＢｉ元素が欠如する。この結果、蛍光特性は得られないと考えられる。酸素圧７００ｍＴｏｒｒの場合には平均自由行程と基板－ターゲット間距離がマッチするためターゲット材料の組成で基板上に膜が付着する。この結果、より好ましい真空度（酸素圧）は４００ｍＴｏｒｒから１０００ｍＴｏｒｒである。 From FIG. 8, the oxygen pressure condition is preferably 200 mTorr or more and 1000 Torr or less, and more preferably 400 mTorr or more and 1000 mTorr or less. Furthermore, the oxygen pressure conditions will be examined. The pulse laser deposition method is a method in which a material having the same composition as the target material composition can be formed on the substrate by matching the distance between the substrate and the target and the mean free path of the target element particles. The melting point of Bi element is 271 ° C., and a material having a low melting point temperature has a feature that it is easily scattered in plasma. Since the mean free path of particles becomes long in low-pressure oxygen of 100 mTorr or less, only the Bi element in the Bi-added CaTiO 3 as the target material is scattered beyond the distance between the substrate and the target, and the Bi element is scattered in the thin film on the substrate. Lack. As a result, it is considered that fluorescence characteristics cannot be obtained. When the oxygen pressure is 700 mTorr, the mean free path and the distance between the substrate and the target match, so that the film adheres on the substrate with the composition of the target material. As a result, a more preferable degree of vacuum (oxygen pressure) is 400 mTorr to 1000 mTorr.
　以上の結果から、バルク材料と同様の蛍光特性を得るためには、酸素圧２００ｍＴｏｒｒ以上の雰囲気で作製した後、１０００℃で大気中熱処理が必要であることが分かった。また、大気中熱処理温度を、９００℃、１１００℃とした場合についても、同様の蛍光が得られたことから、熱処理温度は９００℃以上１１００℃が好適である。 From the above results, it was found that heat treatment in the atmosphere at 1000 ° C. was necessary after producing in an atmosphere having an oxygen pressure of 200 mTorr or more in order to obtain the same fluorescence characteristics as the bulk material. In addition, when the heat treatment temperature in the atmosphere is 900 ° C. and 1100 ° C., similar fluorescence was obtained, and thus the heat treatment temperature is preferably 900 ° C. or higher and 1100 ° C.
　成膜時の基板温度が、６００℃の場合について述べたが、基板温度は、６００℃以上１０００℃以下の温度で薄膜を形成することができる。１０００℃以下の温度ではクラスター成長が支配的であり、ターゲット材料をその化学量論組成で成膜させることができるからである。なお、５００℃以下では非晶質となり蛍光特性は得られない。 Although the case where the substrate temperature during film formation is 600 ° C. has been described, a thin film can be formed at a substrate temperature of 600 ° C. or higher and 1000 ° C. or lower. This is because cluster growth is dominant at a temperature of 1000 ° C. or lower, and the target material can be deposited with its stoichiometric composition. In addition, at 500 degrees C or less, it becomes amorphous and a fluorescence characteristic is not acquired.
　紫外線波長３３０ｎｍで励起した場合について述べたが、励起波長２５０ｎｍ以上、３５０ｎｍ以下の領域で励起した場合についても、同様の結果が得られる。 Although the case where excitation is performed at an ultraviolet wavelength of 330 nm has been described, the same result can be obtained when excitation is performed in a region where the excitation wavelength is 250 nm or more and 350 nm or less.
　本実施例では、Ｂｉの添加量を０.２原子％とした場合について調べたが、同様の傾向が、Ｂｉの添加量０.１～０.４原子％においても得られる。 In this example, the case where the addition amount of Bi was set to 0.2 atomic% was examined, but the same tendency can be obtained even when the addition amount of Bi is 0.1 to 0.4 atomic%.
　実施例３、４では、パルスレーザー堆積法で成膜する例を示したが、基板上にエピタキシャル膜を成長させる成膜法として、パルスレーザー堆積法の他に、スパッタリング法等の気相成長法を用いることができる。その際、薄膜化の温度、酸素圧、及び熱処理温度は、実施例で示した温度と同様の温度で製造することで、実施例と同様の蛍光特性を得ることができる。 In Examples 3 and 4, an example in which a film is formed by a pulse laser deposition method is shown. However, as a film formation method for growing an epitaxial film on a substrate, a vapor phase growth method such as a sputtering method in addition to the pulse laser deposition method. Can be used. At that time, the thin film forming temperature, the oxygen pressure, and the heat treatment temperature are manufactured at the same temperature as the temperature shown in the embodiment, so that the same fluorescence characteristics as in the embodiment can be obtained.
　上記実施の形態等で示した例は、発明を理解しやすくするために記載したものであり、この形態に限定されるものではない。 The examples shown in the above embodiment and the like are described for easy understanding of the invention, and are not limited to this embodiment.
　本発明のペロブスカイト型の無機酸化物蛍光体は、演色特性の優れた白色蛍光特性を実現するものであり、かつ化学的安定性に優れるので、照明器具等に利用できる。また、本発明のペロブスカイト型の無機酸化物蛍光体薄膜は、演色特性の優れた白色蛍光特性を実現するものであり、かつ化学的安定性に優れるので、照明・光源、ディスプレイ用等の薄膜エレクトロルミネッセンスデバイスに利用できる。 The perovskite-type inorganic oxide phosphor of the present invention realizes a white fluorescent property with excellent color rendering properties and is excellent in chemical stability, and thus can be used for lighting equipment and the like. In addition, the perovskite inorganic oxide phosphor thin film of the present invention realizes white fluorescent characteristics with excellent color rendering properties and is excellent in chemical stability. It can be used for luminescence devices.

Claims (13)

  1. 　ペロブスカイト型の無機酸化物蛍光体であって、
    　ＣａＴｉＯ3にＢｉ元素を０.１原子％以上０.４原子％以下添加し、白色蛍光特性を有することを特徴とする無機酸化物蛍光体。     A perovskite-type inorganic oxide phosphor,
    An inorganic oxide phosphor characterized in that a Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and has white fluorescent characteristics.
  2. 　４５０から７００ｎｍの波長全域で発光スペクトルを有することを特徴とする請求項１記載の無機酸化物蛍光体。 2. The inorganic oxide phosphor according to claim 1, wherein the phosphor has an emission spectrum over a wavelength range of 450 to 700 nm.
  3. 　ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加し、９００℃以上１１００℃以下で焼成することを特徴とする請求項１記載の無機酸化物蛍光体の製造方法。 2. The method for producing an inorganic oxide phosphor according to claim 1, wherein Bi element is added to CaTiO 3 in an amount of 0.1 atomic% to 0.4 atomic% and fired at 900 ° C. to 1100 ° C.
  4. 　請求項１乃至２のいずれか１項記載の無機酸化物蛍光体を有することを特徴とする発光装置。 A light emitting device comprising the inorganic oxide phosphor according to claim 1.
  5. 　ペロブスカイト型酸化物の白色蛍光体薄膜であって、
    　ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加したエピタキシャル薄膜であることを特徴とする白色蛍光体薄膜。     A white phosphor thin film of perovskite oxide,
    A white phosphor thin film characterized by being an epitaxial thin film in which Bi element is added in an amount of 0.1 atomic% to 0.4 atomic% to CaTiO 3 .
  6. 　４５０から７００ｎｍの波長全域で白色蛍光特性の発光スペクトルを有することを特徴とする請求項５記載の白色蛍光体薄膜。 6. The white phosphor thin film according to claim 5, wherein the white phosphor thin film has an emission spectrum of white fluorescence characteristics in the entire wavelength range of 450 to 700 nm.
  7. 　前記エピタキシャル薄膜に用いる基板が、ＳｒＴｉＯ3、ＬａＡｌＯ3、ＬａＧａＯ3、ＭｇＯ、ＬａＳｒＧａＯ4のうちのいずれかの基板であることを特徴とする請求項５又は６記載の白色蛍光体薄膜。 The white phosphor thin film according to claim 5 or 6, wherein the substrate used for the epitaxial thin film is any one of SrTiO 3 , LaAlO 3 , LaGaO 3 , MgO, and LaSrGaO 4 .
  8. 　ペロブスカイト型酸化物の白色蛍光体薄膜の製造方法であって、
    　ＣａＴｉＯ3に、Ｂｉ元素を０.１原子％以上０.４原子％以下添加したペロブスカイト型酸化物をターゲット材料として、基板上に、エピタキシャル成長により薄膜を形成することを特徴とする白色蛍光体薄膜の製造方法。     A method for producing a white phosphor thin film of perovskite oxide,
    A white phosphor thin film characterized in that a thin film is formed on a substrate by epitaxial growth using a perovskite oxide in which Bi element is added at 0.1 atomic% or more and 0.4 atomic% or less to CaTiO 3. Production method.
  9. 　前記薄膜を形成後、大気中で、９００℃以上１１００℃以下の熱処理を行うことを特徴とする請求項８記載の白色蛍光体薄膜の製造方法。 The method for producing a white phosphor thin film according to claim 8, wherein after the thin film is formed, heat treatment is performed at 900 ° C to 1100 ° C in the air.
  10. 　６００℃以上１０００℃以下の温度で前記薄膜を形成することを特徴とする請求項８又は９記載の白色蛍光体薄膜の製造方法。 The method for producing a white phosphor thin film according to claim 8 or 9, wherein the thin film is formed at a temperature of 600 ° C or higher and 1000 ° C or lower.
  11. 　２００ｍＴｏｒｒ以上１０００ｍＴｏｒｒ以下の酸素圧雰囲気で前記薄膜を形成することを特徴とする請求項８乃至１０のいずれか１項記載の白色蛍光体薄膜の製造方法。 The method for producing a white phosphor thin film according to any one of claims 8 to 10, wherein the thin film is formed in an oxygen pressure atmosphere of 200 mTorr or more and 1000 mTorr or less.
  12. 　パルスレーザー堆積法によって、前記薄膜を形成することを特徴とする請求項８乃至１１のいずれか１項記載の白色蛍光体薄膜の製造方法。 The method for producing a white phosphor thin film according to any one of claims 8 to 11, wherein the thin film is formed by a pulse laser deposition method.
  13. 　請求項５乃至７のいずれか1項記載の白色蛍光体薄膜を有することを特徴とする発光装置。 A light emitting device comprising the white phosphor thin film according to any one of claims 5 to 7.
PCT/JP2011/067934 2010-08-09 2011-08-05 Inorganic-oxide fluorescent material and thin film of white fluorescent material WO2012020704A1 (en)

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CN114082412A (en) * 2021-12-07 2022-02-25 温州大学 Method for improving calcium titanate photocatalytic activity by using pulse laser

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CN102634339A (en) * 2012-03-31 2012-08-15 昆明理工大学 Red long-afterglow fluorescent material of alkaline earth titanate activated by Bi<2+> and preparation method thereof
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