JP3945710B2 - Solid fluorescent material - Google Patents

Description

  The present invention relates to a solid material that exhibits fluorescence in the visible region and near infrared region when irradiated with ultraviolet rays or electron beams.

In recent years, development of materials having a wide fluorescence wavelength range is desired for application to white phosphors, continuous wavelength tunable solid-state lasers, and the like. Solid materials exhibiting fluorescence are roughly classified into two types: organic materials and inorganic materials. Organic materials have the disadvantage of short lifetime. Inorganic materials, such as semiconductors, exhibit fluorescence directly, and glass, such as glass, does not exhibit fluorescence itself, but becomes fluorescent when an impurity element is added (or a defect is generated) to this. There is a thing. The former fluorescence wavelength range is narrow. Among the latter, the impurity-added inorganic fluorescent material has a long life, but generally has a wavelength unique to the added impurity and exhibits fluorescence with a narrow wavelength range. For this reason, the search and development of an impurity-added inorganic fluorescent material having a wide fluorescent wavelength range has become an issue. Among the impurity-doped inorganic fluorescent materials that have been reported so far, a representative material that exhibits fluorescence in the visible range and in a wide wavelength range is sapphire (Al ₂ O ₃ ) crystal with titanium (Ti) added. The paper shows that the half-value width of fluorescence intensity is 180 nm and the half-value wavelength range of fluorescence intensity is 700 nm to 880 nm [P. f. Multon: J.M. Opt. Soc. Am. B3, 125 (1986)].

One of the alkaline earth thiogallate compounds, calcium thiogallate (2 gallium calcium tetrasulfide, CaGa ₂ S ₄ ) is a transparent inorganic material having a forbidden bandwidth of about 4.2 eV (corresponding to a wavelength of 295 nm). JP-A-10-199675 and JP-A-10-199676 show that when a cerium (Ce) element is added as an impurity to this, it becomes a light-emitting material for an EL element that emits blue light with good color purity. ing.

JP-A-10-199675 JP-A-10-199676 P. f. Multon: J.M. Opt. Soc. Am. B3,125 (1986)

  The impurity-doped inorganic fluorescent material that has been reported so far and exhibits fluorescence in a wide wavelength range from the near infrared to the visible range has a fluorescence wavelength range from near infrared to red. In order to develop environmentally friendly white phosphors and blue-green tunable solid-state lasers that can replace fluorescent lamps that use harmful mercury, the development of new phosphors whose fluorescence wavelength ranges from the near infrared to the blue-green region is hoped for. It is rare.

  Since the present invention is applied to a white phosphor and a new wavelength tunable laser material, a solid fluorescent material having a wide fluorescence wavelength range in which the short wavelength limit of fluorescence is in the blue-green range and the long wavelength limit is in the near infrared range. It is intended to provide.

  The gist of the present invention will be described with reference to the accompanying drawings.

Consists of a crystalline solid containing tin (Sn) as an additive element and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ), and continuously in a wide wavelength range covering almost the entire visible region and near infrared region. The present invention relates to a solid fluorescent material characterized by having a structure exhibiting fluorescence.

In addition, it is composed of crystalline solids containing tin (Sn) and cerium (Ce) as additive elements and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ), and covers almost the entire visible region and near infrared region. The present invention relates to a solid fluorescent material characterized in that it continuously exhibits fluorescence in a wide wavelength range.

Further, it is composed of a crystalline solid containing 0.1 mol% or more of tin (Sn) as an additive element and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ), and is substantially in the visible region and near infrared region. The present invention relates to a solid fluorescent material characterized in that it is configured to continuously exhibit fluorescence in a wide wavelength range over a wide range.

In addition, a crystalline solid containing 0.1 mol% or more of tin (Sn) and 0.1 mol% or more of cerium (Ce) as additive elements and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ). The solid-state fluorescent material is characterized in that it is configured to continuously exhibit fluorescence in a wide wavelength range covering almost the entire visible region and near infrared region.

  Since the present invention is configured as described above, when the material of the present invention is irradiated with ultraviolet light, the half-value wavelength range of the fluorescence shows, for example, from about 850 nm to about 500 nm from the near infrared to the visible range. That is, the material of the present invention has an epoch-making characteristic that cannot be obtained by a conventional inorganic solid fluorescent material, for example, showing fluorescence in a wide wavelength range of 350 nm in the visible-near infrared region. Since it is possible to obtain white light by irradiating the material of the present invention by using an ultraviolet semiconductor light-emitting diode, which has been rapidly improved in recent years, as an irradiation light source, it becomes possible to develop a power-saving all-solid-state white lamp. .

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention that are considered suitable (how to carry out the invention) will be briefly described with reference to the drawings, illustrating the operation of the present invention.

It is a crystalline solid containing tin (Sn) as an additive element and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ). It is continuous and fluorescent in the visible and near infrared regions. It is a solid fluorescent material characterized by showing.

In the above description, including tin (Sn) as an additive element does not necessarily mean that only tin is added, but at least tin may be included, and a case where another element is included is also applicable. For example, as shown in claim 2 and Example 3 , the case of containing cerium (Ce) in addition to tin is applicable.

Based on the fact that digallium calcium tetrasulfide (CaGa ₂ S ₄ ) is the parent material, the material itself or powder obtained by pulverizing the material is identified by 2 gallium calcium tetrasulfide (CaGa ₂ S ₄ ). Is observed, and it can be determined that a crystalline solid of 2 gallium calcium tetrasulfide (CaGa ₂ S ₄ ) is formed.

  The crystalline solid means a polycrystalline sintered body, a polycrystalline or single crystalline film or a bulk body. In addition, fine particles of a polycrystalline sintered body, a thin piece of a polycrystalline or single crystalline film, a polycrystalline or single crystalline microcrystal dispersed in a liquid or an organic polymer, etc. Even if it is in a liquid form or an amorphous form, the basic element exhibiting fluorescence is a crystalline solid, and thus corresponds to the crystalline solid mentioned here.

  Among the materials of the present invention, a method capable of easily producing a material based on 2 gallium calcium tetrasulfide as a base material uses calcium sulfide powder and gallium sulfide powder as a base material, and uses tin powder as an additive raw material. In this method, pellets obtained by press forming powder are sealed in a vacuum ampule and sintered at a temperature of about 800 ° C.

The present invention material 4 sulfide 2 gallium calcium as a host, since there is novelty combination of the additive element of tin, method for producing the actual film or crystal, the method of various existing can be used.

  A specific embodiment 1 of claim 3 that can implement an embodiment of the invention described in claim 1 will be described with reference to the drawings.

  A method for producing a sintered body of 2 gallium calcium tetrasulfide to which tin is added, a fluorescence spectrum of the sintered body by excitation with ultraviolet light, and a fluorescence excitation spectrum will be described.

  The manufacturing method will be described next. Calcium sulfide powder (0.2317 g) and gallium sulfide powder (0.7644 g) are used as the base material, tin powder (3.9 mg) is used as the additive material, and these mixed powders are used using a tablet former. Pressurization was performed on a disk-shaped pellet having a diameter of 10 mm. This was sealed in an ampule made of quartz glass and sintered in an electric furnace at a temperature of 800 ° C. for 24 hours. Thereafter, it was gradually cooled to room temperature. It was confirmed from the X-ray diffraction measurement of the powder obtained by pulverizing the sintered body that the obtained sintered body was crystalline 2 gallium calcium tetrasulfide.

  A measurement example of the fluorescence spectrum will be described next. An ultraviolet light component having a wavelength of 345 nm was extracted from the 150 W xenon lamp light using the spectroscope 1 having f = 10 cm, and the sintered body sample was irradiated. The fluorescence from the sample was condensed into the entrance slit of the spectrometer 2 with f = 1 m using a lens. The intensity of the separated fluorescence appearing from the exit slit of the spectroscope 2 was detected using a photomultiplier tube (R2949). While changing the wavelength of the spectroscope 2, the relationship between the fluorescence intensity obtained from the output of the photomultiplier tube and the wavelength was measured and shown in FIG. However, since the diffraction / transmission efficiency of the spectroscope 2 and the sensitivity of the photomultiplier tube change depending on the wavelength, they were calibrated in advance using a standard lamp. From this figure, it can be seen that the wavelength range where the fluorescence intensity is ½ of the maximum value is from 500 nm to 850 nm.

  A measurement example of the fluorescence excitation spectrum will be described next. The measuring device is the device used for the above-described measurement of the fluorescence spectrum. The wavelength of the spectrometer 2 was fixed at 600 nm, and the 600 nm component of fluorescence was detected with a photomultiplier tube. While changing the wavelength of the spectroscope 1, that is, changing the wavelength at which the sample is irradiated, the relationship between the output of the photomultiplier tube (that is, the intensity of the 600 nm component of the fluorescence) and the irradiation wavelength is measured. was gotten. From this figure, it can be seen that the fluorescent component at 600 nm is mainly generated by irradiation with wavelengths of 315 nm, 345 nm, and 365 nm.

Concrete second embodiment of the present invention of claim 3 which may be made of an embodiment of the invention according to claim 1 will be described with reference to the drawings.

  A method for producing a thin film of digallium calcium tetrasulfide doped with tin, a fluorescence spectrum of this thin film by excitation with ultraviolet light, and a fluorescence excitation spectrum will be described.

The manufacturing method will be described next. First, sintered pellets of 2 gallium calcium tetrasulfide to which tin was added by the method of Example 1 were prepared. Next, a thin film was produced using a standard pulsed laser deposition method using a KrF excimer laser targeting this pellet. Quartz glass was used for the substrate. The substrate was not heated and used at room temperature. The repetition rate of the KrF excimer laser pulse is 30 pulses / second, the pulse energy is 67 mJ, the energy density on the target is 0.7 J / cm ² , the number of irradiation pulses to the target is 36000 pulses, and the distance between the target and the substrate is 4. It was 7 cm. The obtained thin film was heat-treated in a nitrogen atmosphere at 700 ° C. for 30 minutes. The film thickness was 3.7 μm. It was confirmed from the measurement of X-ray diffraction that the obtained thin film was crystalline 2 gallium calcium tetrasulfide.

The measurement method of the fluorescence spectrum was the same as that of Example 1 except that the sample was a thin film of 2 gallium calcium tetrasulfide to which tin was added. The results are shown in Figure 3.

The measurement method of the fluorescence excitation spectrum was the same as Example 1 except that the sample was a thin film of 2 gallium calcium tetrasulfide to which tin was added. The results are shown in Figure 4.

A specific third embodiment of the present invention according to claim 4 that can constitute one embodiment of the second invention will be described with reference to the drawings.

  A method for producing a sintered body of 2 gallium calcium tetrasulfide to which tin and cerium are added, a fluorescence spectrum of this sintered body by excitation with ultraviolet light, and a fluorescence excitation spectrum will be described.

  The manufacturing method will be described next. Calcium sulfide powder (0.2297 g) and gallium sulfide powder (0.7503 g) are used as the base material, and tin powder (7.7 mg) and cerium sulfide powder (12.2 mg) are used as additive materials, and these are mixed. The powder was pressed into a disk-shaped pellet having a diameter of 10 mm using a tablet forming machine. This was sealed in an ampule made of quartz glass and sintered in an electric furnace at a temperature of 800 ° C. for 24 hours. Thereafter, it was gradually cooled to room temperature. It was confirmed from the X-ray diffraction measurement of the powder obtained by pulverizing the sintered body that the obtained sintered body was crystalline 2 gallium calcium tetrasulfide.

The measurement method of the fluorescence spectrum was the same as that of Example 1 except that the sample was a sintered body of 2 gallium calcium tetrasulfide to which tin and cerium were added. The results are shown in Figure 5.

The measurement method of the fluorescence excitation spectrum was the same as that of Example 1 except that the sample was a sintered body of 2 gallium calcium tetrasulfide to which tin and cerium were added. The results are shown in Figure 6.

The present invention is not limited to the first to third embodiments, and the specific configuration of each component can be designed as appropriate.

It is a figure of the fluorescence spectrum by the ultraviolet-light excitation of the sintered compact of 2 gallium calcium tetrasulfide which added the tin of Example 1. FIG. 2 is a diagram of a fluorescence excitation spectrum of a sintered body of 2 gallium calcium tetrasulfide to which tin of Example 1 is added. FIG. It is a figure of the fluorescence spectrum by ultraviolet light excitation of the thin film of 2 gallium calcium tetrasulfide which added the tin of Example 2. FIG. 6 is a fluorescence excitation spectrum of a thin film of 2 gallium calcium tetrasulfide to which tin of Example 2 is added. FIG. It is a figure of the fluorescence spectrum by ultraviolet light excitation of the sintered compact of 2 gallium calcium tetrasulfide which added the tin and cerium of Example 3. FIG. It is a figure of the fluorescence excitation spectrum of the sintered compact of 2 gallium calcium tetrasulfide which added the tin and cerium of Example 3. FIG.

Claims (4)

It is composed of a crystalline solid containing tin (Sn) as an additive element and based on digallium calcium tetrasulfide (CaGa ₂ S ₄ ), and has a wavelength range of about 500 nm to about 850 nm with a fluorescence intensity of half or more. A solid fluorescent material characterized in that it is configured to continuously exhibit fluorescence in a wide wavelength range covering almost the entire visible range and near infrared range. Includes tin (Sn) cerium (Ce) as an additive element, 4 sulfide 2 gallium calcium (CaGa ₂ S ₄₎ constituted by crystalline solid as a matrix, about 450nm fluorescence intensity wavelength range of more than half the 2. The solid fluorescent material according to claim 1, wherein the fluorescent material is continuously configured to exhibit fluorescence in a wide wavelength range extending from approximately 850 nm to approximately 850 nm and in the near-infrared region. Contains 0.1 mol% or more of tin (Sn) as an additive element, digallium calcium tetrasulfide (CaGa) ₂ S _Four ) Is a crystalline solid having a matrix whose fluorescence intensity is half or more, and has a wavelength range from about 500 nm to about 850 nm, and continuously shows fluorescence in a wide wavelength range covering almost the entire visible range and near infrared range. A solid fluorescent material characterized by that. It contains 0.1 mol% or more of tin (Sn) and 0.1 mol% or more of cerium (Ce) as additive elements. ₂ S _Four ) Is a crystalline solid having a matrix whose fluorescence intensity is more than half-value, and has a wavelength range from about 450 nm to about 850 nm, and continuously shows fluorescence in a wide wavelength range from the visible region to the near infrared region. A solid fluorescent material characterized by that.

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