TW202104547A - Red phosphor and method for producing same - Google Patents

Abstract

Provided are: a red phosphor exhibiting excellent optical characteristics and durability even in high temperature, high humidity environments; and a method for producing the same. The red phosphor according to the present invention is characterized by containing an Mn-activated complex fluoride represented by general formula (1), and bismuth. (1) A2MF6:Mn4+ (In the formula, A represents at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and M represents at least one tetravalent element selected from the group consisting of silicon, germanium, tin, titanium, zirconium and hafnium.).

Description

Red phosphor and manufacturing method thereof

The present invention relates to a red phosphor that is excited by excitation light such as ultraviolet light and blue light to emit red light and a manufacturing method thereof. More specifically, it relates to a red phosphor with excellent optical properties and durability in a high temperature and high humidity environment by activating Mn (manganese) bisfluoride containing bismuth, and a method for manufacturing the same.

Compared with fluorescent lamps, white LEDs (Light Emitting Diode) have a longer life and lower power consumption. Therefore, the popularization of backlights as lighting fixtures or displays has been rapidly advancing. The white LEDs of commercially available lighting fixtures are composed of a combination of blue LEDs that emit light from near-ultraviolet light to blue light, and yellow phosphors excited by these lights. In this way, the white LED mixes the light emitted by the blue LED and the light emitted by the yellow phosphor, making it possible to irradiate the pseudo-white light. However, because the pseudo-white light irradiated by the white LED has less or no luminous components in the red light region, the pseudo-white light is compared with natural light (or sunlight, black body radiation), and it has color rendering (it means the same as the aforementioned natural light). Compare the characteristics of the color appearance of the lighting when viewing the object. For example, when the object is illuminated by lighting, when the color looks similar to the situation illuminated by natural light, it shows the problem of high color rendering.

Therefore, it is necessary to be excited by the ultraviolet light emitted by the near-ultraviolet LED or the blue light emitted by the blue LED to emit a red phosphor that emits red light. As such a red phosphor, in recent years, Mn ⁴⁺ ions of transition metals have been developed as the emission center, including Mn activated difluoride (K ₂ SiF ₆ : Mn ⁴⁺ (KSF: Mn)) that emits red light. The use of the resulting phosphor composition (for example, refer to Patent Documents 1, 2 and Non-Patent Document 1) is rapidly developing. KSF: Mn has an excitation band at the wavelength of blue light, and a red emission peak with a narrow half-width in the narrow band of 600 to 650 nm.

KSF: Mn uses K ₂ SiF ₆ crystals to act as the framework of the phosphor and dissolves Mn ⁴⁺ ions in the hexacoordinate-octahedral position of Si ⁴⁺ _{formed by SiF 6} ^{2- ions.} The MnF ₆ ^2- octahedral position is formed and used as the emission center.

However, the red phosphor containing this KSF: Mn is accused of a practical problem in that the surface of the particles becomes black due to contact with water or water vapor in a high temperature and high humidity environment. Specifically, the tetravalent manganese ions constituting the red phosphor react with water on the surface of the particles of the red phosphor to generate manganese dioxide, and the manganese dioxide produces excitation light absorption and fluorescence Inhibition of the optical properties and the deterioration of optical properties over time (decrease in durability). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Special Publication No. 2009-528429 [Patent Document 2] WO2015/093430 [Non-Patent Literature]

[Non-Patent Document 1] H. D. Nguyen, C. C. Lin, R. S. Liu, Angew. Chem. 54 Volume 37, Page 10862 (2015)

[The problem to be solved by the invention]

The present invention was completed in view of the aforementioned problems, and its purpose is to provide a red phosphor with excellent optical properties and durability in a high temperature and high humidity environment, and a method for manufacturing the same. [Means to solve the problem]

In order to solve the aforementioned problems, the red phosphor of the present invention is characterized by including Mn-activated bisfluoride represented by the following general formula (1), and bismuth.

A ₂ MF ₆ : Mn ⁴⁺ (1) (In the formula, the aforementioned A series represents at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and the aforementioned M series represents selection Free silicon, germanium, tin, titanium, zirconium and hafnium of at least one tetravalent element in the group).

In the aforementioned configuration, the Mn-activated bisfluoride is particulate, and the bismuth can be present on at least a part of the surface of the particulate Mn-activated bisfluoride.

In addition, in the aforementioned configuration, a coating layer may be provided on the surface of the particulate Mn-activated bisfluoride, and the coating layer may contain the aforementioned bismuth.

Furthermore, in the aforementioned configuration, it is preferable that the aforementioned coating layer contains a bismuth monomer and/or a bismuth compound.

Further, in the above-described configuration, the bismuth compound is preferably selected from the group consisting of _{BiF 3, BiCl 3, BiBr 3} , BiI 3, Bi 2 O 3, Bi 2 S 3, Bi 2 Se 3, BiSb, Bi 2 Te 3, Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ H ₁₀ BiK ₃ At least one of the group consisting of O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi and C ₆ H ₄ (OH)CO ₂ BiO･H _{2 O.}

In the aforementioned configuration, the content of the aforementioned bismuth is preferably in the range of 0.01% by mass to 15% by mass relative to the total mass of the red phosphor.

In the aforementioned configuration, the molar ratio of the Mn in the Mn-activated bifluoride relative to the total molar number of the M and Mn is preferably in the range of 0.005 to 0.15.

In order to solve the aforementioned problems, the manufacturing method of the red phosphor of the present invention is characterized by including the step of contacting the Mn-activated bisfluoride represented by the following general formula (1) with a treatment solution containing bismuth.

A ₂ MF ₆ : Mn ⁴⁺ (1) (In the formula, the aforementioned A series represents at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and the aforementioned M series represents selection Free silicon, germanium, tin, titanium, zirconium and hafnium of at least one tetravalent element in the group).

In the aforementioned configuration, the content of the bismuth in the treatment liquid is preferably in the range of 0.01% by mass to 15% by mass relative to the total mass of the treatment liquid.

In the aforementioned configuration, the solvent of the aforementioned treatment liquid is preferably water, an organic solvent, a mixed solvent of these, or an acidic solvent of these.

In the aforementioned configuration, the acidic solvent is an acidic solvent containing hydrogen fluoride, and the mixing ratio of the acidic solvent containing hydrogen fluoride and the bismuth is preferably in the range of 30:1 to 3500:1 on a mass basis.

In the aforementioned configuration, the concentration of the hydrogen fluoride in the acidic solvent containing the hydrogen fluoride is preferably in the range of 1% by mass to 70% by mass relative to the total mass of the acidic solvent.

In the aforementioned structure, the aforementioned bismuth system is preferably selected from the group consisting of Bi monomer, BiF ₃ , BiCl ₃ , BiBr ₃ , _{BiI 3} , Bi ₂ O ₃ , Bi ₂ S ₃ , Bi ₂ Se ₃ , BiSb, Bi ₂ Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH ) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ H ₁₀ At least one of the group consisting of BiK ₃ O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi and C ₆ H ₄ (OH)CO ₂ BiO･H ₂ O is included in the aforementioned treatment liquid. [Effects of the invention]

The present invention exerts the various effects described below through the aforementioned means. That is, the red phosphor according to the present invention contains bismuth in addition to the Mn-activated bisfluoride to reduce or prevent the ^{reaction of Mn 4+} with water to cause the production of colored manganese dioxide. As a result, since the absorption of excitation light or the suppression of fluorescence by manganese dioxide can be prevented, it is possible to provide a good optical characteristic and reduce the degradation of the optical characteristic caused by time change in a high temperature and high humidity environment, Red phosphor with excellent durability.

In addition, according to the method for producing a red phosphor of the present invention, by activating the bismuth fluoride to Mn and contacting the treatment solution containing bismuth, a red phosphor containing bismuth can be produced. As a result, it is possible to produce a red phosphor with good optical properties, reduce the degradation of optical properties due to changes over time in a high temperature and high humidity environment, and have excellent durability.

(Red phosphor)

The red phosphor according to the embodiment of this embodiment will be described below. The red phosphor according to the embodiment of the present embodiment contains Mn-activated bisfluoride (hereinafter, sometimes referred to as "Mn-activated bisfluoride") represented by the following general formula (1), and bismuth.

A ₂ MF ₆ : Mn ⁴⁺ (1) (In the formula, the aforementioned A series represents at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and the aforementioned M series represents selection Free silicon, germanium, tin, titanium, zirconium and hafnium of at least one tetravalent element in the group).

The red phosphor of this embodiment may be a single red phosphor or a mixture of two or more red phosphors.

_{In the general formula A 2} MF ₆ : Mn ⁴⁺ , which represents the aforementioned Mn-activated bisfluoride, "A ₂ MF ₆ "represents the composition of the matrix crystal of the red phosphor. In addition, "Mn ⁴⁺ "means the activating ion that becomes the luminescence center.

Here, the term "activation" in this specification means ^{adding Mn 4+ which is} an activator to _{A 2} MF ₆ that is the precursor crystal in order to exhibit fluorescence. Examples of the activated form include a form in which Mn ⁴⁺ replaces a part of any atom _{constituting A 2} MF _6. In the embodiment of this embodiment, Mn ⁴⁺ is preferably substituted for M of the matrix crystal.

As the Mn activated difluoride represented by the general formula A ₂ MF ₆ : Mn ⁴⁺ _{, specifically, for example, Li 2} SiF ₆ : Mn ⁴⁺ , Na ₂ SiF ₆ : Mn ⁴⁺ , K ₂ SiF ₆ : Mn ⁴⁺ , Rb ₂ SiF ₆ : Mn ⁴⁺ , Cs ₂ SiF ₆ : Mn ⁴⁺ , Li ₂ GeF ₆ : Mn ⁴⁺ , Na ₂ GeF ₆ : Mn ⁴⁺ , K ₂ GeF ₆ : Mn ⁴⁺ , Rb ₂ GeF ₆ : Mn ⁴⁺ , Cs ₂ GeF ₆ : Mn ⁴⁺ , Li ₂ SnF ₆ : Mn ⁴⁺ , Na ₂ SnF ₆ : Mn ⁴⁺ , K ₂ SnF ₆ : Mn ⁴⁺ , Rb ₂ SnF ₆ : Mn ^{4 +} , Cs ₂ SnF ₆ : Mn ⁴⁺ , Li ₂ TiF ₆ : Mn ⁴⁺ , Na ₂ TiF ₆ : Mn ⁴⁺ , K ₂ TiF ₆ : Mn ⁴⁺ , Rb ₂ TiF ₆ : Mn ⁴⁺ , Cs ₂ TiF ₆ : Mn ⁴⁺ , Li ₂ ZrF ₆ : Mn ⁴⁺ , Na ₂ ZrF ₆ : Mn ⁴⁺ , K ₂ ZrF ₆ : Mn ⁴⁺ , Rb ₂ ZrF ₆ : Mn ⁴⁺ , Cs ₂ ZrF ₆ : Mn ⁴⁺ , Li ₂ HfF ₆ : Mn ⁴⁺ , Na ₂ HfF ₆ : Mn ⁴⁺ , K ₂ HfF ₆ : Mn ⁴⁺ , Rb ₂ HfF ₆ : Mn ⁴⁺ , Cs ₂ HfF ₆ : Mn ⁴⁺ and the like. Among these Mn activated difluorides, from the viewpoints of ease of acquisition and ease of synthesis, K ₂ SiF ₆ : Mn ⁴⁺ , K ₂ TiF ₆ : Mn ⁴⁺ , K ₂ GeF _{6 are preferred} : Mn ⁴⁺ , Na ₂ SiF ₆ : Mn ⁴⁺ , Na ₂ TiF ₆ : Mn ⁴⁺ , Na ₂ GeF ₆ : Mn ⁴⁺ , more preferably K ₂ SiF ₆ : Mn ⁴⁺ , K ₂ TiF ₆ : Mn ⁴⁺ . Furthermore, Mn activated bifluoride can be selected in accordance with the optical properties required by various applications. Accordingly, the exemplified Mn activated difluoride is not particularly limited.

Here, the "optical characteristics" in this specification means the absorptivity and internal quantum efficiency of red phosphors and the like. The so-called "absorption rate" refers to the efficiency of the red phosphor to absorb the excitation light. For example, when the peak of the spectral emission brightness of the excitation light (wavelength 449nm) irradiated from the blue LED is set as Ex1, and the peak of the unabsorbed excitation light of the red phosphor is set as Ex2, the absorption rate α is the following Numerical formula (1) expresses. Absorption rate α(%)=(Ex1-Ex2)/Ex1×100 (1)

In addition, the so-called "internal quantum efficiency" refers to the efficiency of converting the excitation light absorbed by the red phosphor into fluorescent light. For example, under the excitation light (wavelength 449nm) from the blue LED, when the peak of the spectral emission brightness of the red phosphor is set as Ex2, the internal quantum efficiency η is given by the following formula (2) Said. Internal quantum efficiency η(%)=Em/(Ex1-Ex2)×100 (2)

The Mn activated bisfluoride is solid, and more preferably in the form of particles. When the Mn activated bisfluoride is in the form of particles, if its average particle size is for the excitation light, compared to the absorption and conversion, the scattering ratio will not become too large, and in order to be installed in the LED device, it will not be generated when mixed with resin. The scope of the problem is not particularly limited.

The molar ratio of Mn is preferably in the range of 0.005 to 0.15, and more preferably in the range of 0.01 to 0.13 to the total molar ratio of M and Mn in the red phosphor (or Mn activated difluoride). It is more preferably in the range of 0.02 to 0.12, and particularly preferably in the range of 0.03 to 0.1. By setting the aforementioned molar ratio to 0.005 or more, the good luminous intensity of the red phosphor can be maintained. On the other hand, by setting the aforementioned molar ratio to 0.15 or less, the durability of the red phosphor in a high temperature and high humidity environment can be suppressed from excessively decreasing.

In addition, the term "durability" in this specification refers to the degree to which the initial optical properties of the red phosphor are maintained when the red phosphor is stored for a certain period of time under a high temperature and high humidity environment. The meaning of optical properties is as described above.

The aforementioned bismuth may be present on at least a part of the surface of the Mn-activated bisfluoride, and further, it is preferable to coat at least a part of the surface as a coating layer. In addition, bismuth may exist in the form of bismuth monomer and/or bismuth compound.

It is believed that the tetravalent manganese ions that constitute the Mn-activated bisfluoride react with water to produce colored manganese dioxide, and blackening occurs on the surface of the Mn-activated bisfluoride particles. It is speculated that under high temperature and high humidity, the occurrence of this blackening will be accelerated, resulting in the deterioration of the optical properties of the red phosphor and the decrease in durability. However, in the case of the red phosphor of this embodiment, bismuth is present on at least a part of the surface of the Mn-activated bisfluoride, and the tetravalent manganese ion comes into contact with water to reduce or prevent the reaction. Especially when bismuth is present on the surface of the Mn-activated bifluoride as a coating layer, the penetration of water or water vapor into the red phosphor is suppressed, thereby achieving improved durability and optical characteristics in a high-temperature and high-humidity environment.

From the viewpoint of preventing the generation of manganese dioxide, it is preferable that the entire surface of the Mn-activated bisfluoride is coated with a coating layer containing bismuth. However, coating the entire surface of the Mn-activated bifluoride with the coating layer may not be suitable for industry from the viewpoint of manufacturing cost and ease of manufacturing. Even if bismuth is present on a part of the surface of the Mn-activated bisfluoride, the durability and optical characteristics under high temperature and high humidity environments can be improved, so it is not necessary to use the entire surface of the Mn-activated bisfluoride. The coating layer covers. Furthermore, the degree of coverage by the coating layer is preferably changed appropriately in accordance with the application of the red phosphor and the required performance of the application.

As the film thickness of the aforementioned coating layer, in the area of the Mn-activated bifluoride covered by the coating layer, if at least the optical properties by contact with water and the degree of durability under high temperature and high humidity environment are improved , It is not particularly limited.

The aforementioned bismuth compound is not particularly limited as long as it does not adversely affect the optical properties of the red phosphor. Specific bismuth compound, for example, selected from the group comprising BiF _3, BiCl _3, BiBr _3, and is made of a bismuth halide BiI _{3 (III), Bi 2 O 3} , Bi 2 S 3, Bi 2 Se 3, BiSb, Bi ₂ Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ At least one of the group consisting of H ₁₀ BiK ₃ O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi, and C ₆ H ₄ (OH)CO ₂ BiO･H _{2 O.} Among these the bismuth compound, preferably comprising BiF _3, BiCl _3, BiBr _3, and is made of a bismuth halide BiI _{3 (III), Bi 2 O 3} , Bi 2 S 3, Bi 2 Se 3, BiSb, Bi 2 Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , 4BiNO ₃ (OH) ₂ ･ Inorganic bismuth salts such as BiO(OH) and C ₃ F ₉ O ₉ S ₃ Bi are more preferably BiF ₃ and Bi(NO ₃ ) ₃ . _{Furthermore, the bismuth compound is particularly preferably BiF 3} from the viewpoint that the durability and optical properties of the red phosphor under a high temperature and high humidity environment become better.

The content of the aforementioned bismuth relative to the total mass of the red phosphor is preferably in the range of 0.01% by mass to 15% by mass, more preferably in the range of 0.01% by mass to 10% by mass, and still more preferably in the range of 0.05% by mass to 10% by mass The range of% is particularly preferably the range of 0.1% by mass to 5% by mass. By setting the content of the bismuth compound to 0.01% by mass or more, the durability of the red phosphor under high temperature and high humidity environments can be further improved. On the other hand, by setting the content of the bismuth compound to 15% by mass or less, the decrease in optical characteristics can be further reduced.

The (initial) absorption rate of the red phosphor is preferably in the range of 50% to 100%, more preferably in the range of 55% to 100%, and still more preferably in the range of 60% to 100%. By setting the absorption rate to 50% or more, the optical characteristics of the red phosphor can be maintained well. In particular, in the present invention, even after storage for a certain period of time in a high temperature and high humidity environment, the reduction in the absorption of excitation light due to the red phosphor is suppressed, thereby achieving the maintenance of good optical characteristics. Furthermore, the aforementioned range of absorptance values is not only the initial absorptivity of the red phosphor, but also the absorptance after storing the red phosphor in a high-temperature and high-humidity environment for a certain period of time. The definition of absorption rate is as mentioned above.

The (initial) internal quantum efficiency of the red phosphor is preferably in the range of 70% to 100%, more preferably in the range of 75% to 100%, and still more preferably in the range of 80% to 100%. By setting the internal quantum efficiency to 70% or more, the luminous efficiency of the red phosphor can be maintained well. Furthermore, the aforementioned numerical range of internal quantum efficiency is not only the initial internal quantum efficiency of the red phosphor, but also the internal quantum efficiency after storing the red phosphor in a high-temperature and high-humidity environment for a certain period of time. The definition of internal quantum efficiency is as described above.

The red phosphor of this embodiment is suitable as a red phosphor for a white LED using blue light as a light source, for example. The red phosphor of this embodiment can be suitably used in light-emitting devices such as lighting fixtures and video display devices.

(Manufacturing method of red phosphor) Next, the method of manufacturing the red phosphor according to the embodiment of the present embodiment will be described below. The manufacturing method of the red phosphor of this embodiment includes at least the step of activating the Mn bisfluoride represented by the aforementioned general formula (1) and contacting the treatment solution containing bismuth. In this contacting step, the surface modification (surface treatment) of the Mn-activated bisfluoride is performed by contacting the Mn-activated bisfluoride with a treatment solution containing bismuth, and bismuth is present on at least a part of the surface of the Mn-activated bisfluoride It is more preferable to make it possible to form a coating layer containing bismuth.

The aforementioned treatment solution containing bismuth contains bismuth monomer and/or bismuth compound. In the treatment liquid containing bismuth, in addition to the case where all of the added bismuth monomer and/or bismuth compound are completely dissolved, some of them cannot be dissolved and exist as insolubles.

Examples of the bismuth compound, selected from the group consisting of include contains BiF _3, BiCl _3, BiBr _3, and is made of a bismuth halide BiI _{3 (III), Bi 2 O 3} , Bi 2 S 3, Bi 2 Se 3, BiSb, Bi 2 Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH ) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ H ₁₀ At least one of the group consisting of BiK ₃ O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi, and C ₆ H ₄ (OH)CO ₂ BiO･H _{2 O.}

As the solvent of the treatment liquid containing bismuth, water, organic solvents, mixed solvents of these, or acidic solvents of these can be cited.

The organic solvent is not particularly limited, and examples include methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl alcohol, methyl acetate, ethyl acetate, tetrahydrofuran, and 1,2-dimethoxyethane. Ethane etc. Among these organic solvents, methyl alcohol, ethyl alcohol, isopropyl alcohol, and isobutyl alcohol are preferred from the viewpoint of ease of acquisition or simplicity of working environment, and methyl alcohol is particularly preferred. And ethyl alcohol.

The aforementioned acidic solvent means a solvent containing an acid having a proton. The acid having a proton is not particularly limited, and examples thereof include hydrogen fluoride, nitric acid, sulfuric acid, and hydrochloric acid. From the viewpoint of the manufacturing process or the characteristics of the red phosphor, hydrogen fluoride and nitric acid are preferred, and hydrogen fluoride is particularly preferred.

The content of bismuth in the aforementioned treatment solution is preferably in the range of 0.01% by mass to 15% by mass, more preferably in the range of 0.05% by mass to 10% by mass, and particularly preferably in the range of 0.1% by mass relative to the total mass of the treatment solution. ～5% by mass range. By setting the content of bismuth to 15% by mass or less, the optical properties of the red phosphor can be maintained well. On the other hand, by setting the content of bismuth to 0.01% by mass or more, the optical properties and durability of the red phosphor under high temperature and high humidity environments can be further improved.

The content of bismuth can be measured by using a chemical analysis device such as atomic absorption spectroscopy or ICP emission spectroscopy (high frequency inductively coupled plasma emission spectroscopy) for the filtrate when filtering the treatment solution containing bismuth. In addition, the difference between the mass of bismuth added to the aforementioned solvent and the mass of the dissolved residue (filtrate) remaining on the filter paper when the treatment liquid containing bismuth is filtered can be taken as the bismuth dissolved in the treatment liquid containing bismuth The content (concentration) is calculated.

As the solvent of the treatment liquid, an acidic solvent containing hydrogen fluoride is used, that is, when hydrofluoric acid or a mixed solvent of the hydrofluoric acid and an organic solvent is used, the mixing ratio of the acidic solvent containing the hydrogen fluoride to bismuth is preferably on a mass basis The range from 30:1 to 3500:1 is more preferably the range from 100:1 to 3500:1, and the range from 500:1 to 1500:1 is particularly preferred. By setting the aforementioned mixing ratio to 3500:1 or less, the amount of treatment liquid discharged as waste liquid can be reduced, making it possible to reduce the environmental load. On the other hand, by setting the aforementioned mixing ratio to 30:1 or more, the dispersibility of the bismuth monomer and/or bismuth compound in the treatment solution can be improved, and the surface modification of the bisfluoride activated by Mn can prevent the Bismuth and the like are unevenly present on the surface of the Mn activated bifluoride.

In addition, the concentration of hydrogen fluoride in the acidic solvent containing hydrogen fluoride is preferably in the range of 1% by mass to 70% by mass, more preferably in the range of 10% by mass to 50% by mass, with respect to the total mass of the acidic solvent. It is 20% by mass to 40% by mass. By setting the concentration of hydrogen fluoride to 70% by mass or less, it is possible to suppress the decrease in the solubility of the Mn-activated bisfluoride with respect to the acidic solvent containing hydrogen fluoride. On the other hand, by setting the concentration of hydrogen fluoride to 1% by mass or more, it is possible to suppress an increase in the amount of treatment liquid used, and to achieve an improvement in productivity.

The method of contacting the above-mentioned Mn-activated bisfluoride with the treatment liquid containing bismuth is not particularly limited. For example, a method of adding (dipping) the Mn-activated bisfluoride of the object to be treated in the treatment liquid, or spraying the treatment liquid The method and so on. From the viewpoint of industrial production of red phosphors, a method of adding (immersing) Mn-activated bisfluoride to the treatment liquid is preferred. By the input of Mn-activated bisfluoride, a suspension in which Mn-activated bisfluoride is dispersed in the treatment solution is obtained. The number of injections is not particularly limited. Except for the case where the Mn-activated bisfluoride is injected into the treatment liquid once, the injection may be performed multiple times.

The mass ratio of the Mn-activated bisfluoride to the Mn-activated bisfluoride is not particularly limited when the Mn-activated bisfluoride is put into the treatment solution. The range that does not affect the subsequent stirring or filtration can be adjusted appropriately (for stirring and filtering). The details will be described later). However, from the viewpoint of work efficiency, the mass ratio of the treatment liquid and the Mn activated difluoride is preferably in the range of 100:1 to 2:1, and more preferably in the range of 10:1 to 3:1. By setting the aforementioned mass ratio to 100:1 or more, the amount of Mn-activated bisfluoride to be treated can be prevented from becoming too small, and the productivity of the red phosphor can be reduced. On the other hand, by setting the aforementioned mass ratio to 2:1 or less, the dispersibility of the Mn-activated bisfluoride in the treatment liquid is good, and the bismuth compound can be uniformly imparted.

After the aforementioned step of contacting the Mn-activated bisfluoride with the treatment liquid, it is preferable to sequentially perform the stirring step of the resulting suspension, the solid-liquid separation step of the suspension, and the solid-liquid separation step of solid washing. And the drying step of the solid after washing.

The stirring method in the aforementioned stirring step is not particularly limited, and it can be performed using a known stirring device or the like. The stirring time of the suspension is not particularly limited, and can be appropriately adjusted according to the efficiency of the manufacturing equipment. The stirring speed is not particularly limited, and can be set according to appropriate needs.

The aforementioned solid-liquid separation step is a step of separating solid particles in dispersion from the suspension after the stirring step. The method of solid-liquid separation is not particularly limited. For example, a method of filtering the suspension, or a method of standing the suspension to precipitate solid particles in dispersion, and then performing decantation, etc. may be mentioned. The standing time of the suspension is not particularly limited, as long as the solid particles can be sufficiently precipitated.

The aforementioned washing step is performed for washing the filter cake obtained by solid-liquid separation. In this cleaning step, water, organic solvents, mixed solvents of these or acidic solvents can be used as cleaning agents. The washing time or the number of washing times is not particularly limited, and can be set according to appropriate needs.

The organic solvent used in the washing step is not particularly limited, and examples include methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl alcohol, methyl acetate, ethyl acetate, tetrahydrofuran, 1, 2 -Dimethoxyethane, acetone, etc. From the viewpoint of ease of acquisition and simplicity of the working environment, methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl alcohol, and acetone are preferred, and ethyl alcohol and isopropyl alcohol are particularly preferred. And acetone.

In addition, the aforementioned acidic solvent used in the washing step means a solution containing an acid having a proton. The acid having a proton is not particularly limited, and examples thereof include hydrogen fluoride, nitric acid, sulfuric acid, and hydrochloric acid. The content of the proton-containing acid relative to the total mass of the acidic solvent is preferably in the range of 0.1% by mass to 60% by mass, more preferably in the range of 1% by mass to 55% by mass, and particularly preferably in the range of 5% by mass to 50% by mass %In the range.

The aforementioned drying step is performed on the filter cake after the washing step. Thereby, the solvent of the treatment liquid remaining in the filter cake can be distilled off, or the detergent used in the cleaning step. It does not specifically limit as a drying method, For example, heat drying, hot air drying, etc. are mentioned. When heating and drying, it is preferably performed in a nitrogen atmosphere. The drying temperature is preferably in the range of 60°C to 200°C, more preferably in the range of 70°C to 150°C, and particularly preferably in the range of 80°C to 110°C. By setting the drying temperature to 60°C or higher, the drying efficiency can be maintained well. In addition, it is possible to suppress and prevent the remaining of impurities, and it is possible to suppress the degradation of the optical characteristics of the red phosphor caused by the remaining of the impurities. On the other hand, by setting the drying temperature to 200°C or lower, the resulting red phosphor can be prevented from being deteriorated due to heat. In the case of heating and drying, the drying time is preferably in the range of 0.5 hours to 20 hours, and more preferably in the range of 2 hours to 15 hours. By setting the drying time to 0.5 hours or more, the remaining of impurities can be suppressed and the reduction in the optical characteristics of the red phosphor caused by the remaining of the impurities can be suppressed. On the other hand, by setting the drying time to 20 hours or less, the reduction in the production efficiency of the red phosphor can be prevented.

From the above, it is possible to manufacture a red phosphor with bismuth present on at least a part of the surface of the Mn-activated bisfluoride. Furthermore, the precipitation of bismuth monomer and/or bismuth compound on the surface of the Mn-activated bisfluoride is presumed to be the process of stirring the suspension in the aforementioned stirring step. Or it is inferred that the Mn activated bisfluoride with the treatment liquid attached to the surface is dried in the aforementioned drying step, and the solvent of the treatment liquid is distilled off, and the bismuth monomer and/or bismuth compound precipitates on the Mn activated bisfluoride s surface.

In addition, when the treatment solution containing bismuth only dissolves a part of the bismuth and contains an insoluble component of bismuth, the insoluble component of bismuth may remain as a monomer on the surface of the Mn-activated bisfluoride. However, in the present invention, even in such a situation, as long as the optical properties of the red phosphor are not adversely affected, the insoluble bismuth may remain on the surface of the Mn-activated bisfluoride. However, if the remaining insoluble components of bismuth degrade the optical properties of the red phosphor, etc., it is preferable to use a treatment solution in which bismuth is completely dissolved, or to adjust the content of bismuth so as not to generate insoluble components.

(something else) In the above description, a suitable embodiment of the present invention will be described. However, the present invention is not limited to this embodiment, and can be implemented in various other forms.

For example, in the above description, regarding the manufacturing method of the red phosphor, as a method of contacting the bismuth-containing treatment solution with Mn-activated bisfluoride, a method of adding Mn-activated bisfluoride to the treatment solution can be cited. However, the present invention is not limited to this method. For example, it may be a method of spraying the aforementioned treatment liquid on the Mn-activated bisfluoride which is the object to be treated. The spray amount of the treatment liquid is not particularly limited, and can be appropriately set. Furthermore, after spraying the Mn-activated bisfluoride of the treatment liquid, it is preferable to distill off the solvent component of the treatment liquid remaining on the surface of the Mn-activated bisfluoride. The method of distillation is not particularly limited. For example, the aforementioned drying step can be carried out.

In addition, the manufacturing method of the Mn-activated bisfluoride which is the raw material of the red phosphor is not particularly limited, and a known method can be adopted. For example, a method of dissolving a compound containing a constituent element of Mn-activated bifluoride in a hydrofluoric acid solution and mixing them to perform reaction crystallization (refer to HD Nguyen, CC Lin, RS Liu, Angew. Chem. 54 volume 37 No. 10862 (2015)), a method of dissolving or dispersing all the constituent elements of Mn-activated bisfluoride in a hydrofluoric acid solution, and then evaporating and concentrating it to precipitate (refer to Japanese Patent Application No. 2009-528429) ). Dissolve compounds containing the constituent elements of Mn-activated bisfluoride in a hydrofluoric acid solution, and add solid Mn-activated bisfluoride to the manganese that does not contain one of the constituent elements, and make K ₂ SiF ₆ : The crystallization of Mn ⁴⁺ precipitates, filtering and drying method (refer to WO2015/093430), etc. [Example]

Hereinafter, although the present invention will be described in detail using examples, the present invention is not limited to the following examples as long as it does not exceed the gist.

(Generation of Mn activated bifluoride) According to the method described in H. D. Nguyen, C. C. Lin, R. S. Liu, Angew. Chem. 54, No. 37, page 10862 (2015), the following method was used to synthesize Mn activated difluoride.

First, put 35 ml of a 48% by mass hydrofluoric acid solution into a PFA container with an internal volume of 0.1L. Next, while stirring the hydrofluoric acid solution, 1.2 g of SiO ₂ was added and dissolved. Furthermore, 0.3 g of K ₂ MnF ₆ was added to this solution and dissolved.

Next, 3.5 g of KF was slowly added to the aforementioned solution over 15 minutes to obtain crystals. After washing this crystal with a 20% by mass hydrofluoric acid solution and acetone, it was dried at 70°C for 6 hours. _{In this way, K 2} SiF ₆ : Mn ⁴⁺ , which is a Mn activated double fluoride, is obtained.

(Example 1) _{0.15 g of bismuth fluoride (BiF 3} ) was added to 16.6 ml of hydrofluoric acid with a concentration of 43% by mass, and stirred for 5 minutes to prepare a suspension (hydrofluoric acid: bismuth=1408:1 (mixed on a mass basis) ratio)). Next, while stirring this suspension, _{5.3 g of the aforementioned K 2} SiF ₆ :Mn ^{4+ was added} , and the mixture was further stirred for 10 minutes.

After the stirring is over, let the suspension stand for 10 minutes to allow the solids in the dispersion to settle. Then, suction filtration is performed to recover the filtrate. Furthermore, after adding ethanol to the filtrate, suction filtration was performed again to remove the supernatant, and this operation was repeated to wash the filtrate. The washed filtrate is recovered and dried at a drying temperature of 105°C in a nitrogen environment to evaporate the ethanol. In this way, the red phosphor of Example 1 was produced.

(Example 2) In this example, the addition amount of bismuth fluoride was changed from 0.15 g to 0.05 g (hydrofluoric acid: bismuth = 423:1 (mixing ratio on a mass basis)). Except for this, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 2 was produced.

(Example 3) In this example, the addition amount of bismuth fluoride was changed from 0.15 g to 0.015 g (hydrofluoric acid: bismuth = 141:1 (mixing ratio on a mass basis)). Other than that, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 3 was produced.

(Example 4) In this example, the addition amount of bismuth fluoride was changed from 0.15 g to 0.60 g (hydrofluoric acid: bismuth = 35:1 (mixing ratio on a mass basis)). Other than that, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 4 was produced.

(Example 5) In this example, the amount of bismuth fluoride added was changed from 0.15 g to 0.90 g, and the amount of hydrofluoric acid with a concentration of 43% by mass was changed from 16.6 ml to 21.5 ml (hydrofluoric acid: bismuth = 30:1 (quality basis The mixing ratio)). Other than that, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 5 was produced.

(Example 6) In this example, the bismuth fluoride was changed to a 40% by mass bismuth nitrate aqueous solution, and the addition amount was changed from 0.15 g to 0.56 g (hydrofluoric acid: bismuth=140:1 (mixing ratio on a mass basis)). Except for these, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 6 was produced.

(Example 7) In this example, the concentration of hydrofluoric acid was changed from 43% by mass to 35% by mass, and the amount of bismuth fluoride added was changed from 0.15g to 0.015g (hydrofluoric acid: bismuth=1408:1 (mixed on a mass basis) ratio)). Except for these, the same procedure as in Example 1 was carried out, and a red phosphor related to Example 7 was produced.

(Comparative Example 1) In this comparative example, the aforementioned K ₂ SiF ₆ : Mn ^{4+ was} used as the red phosphor.

(Evaluation of red phosphor) Regarding the red phosphors of Examples 1-7 and Comparative Example 1, each evaluation was performed by the method described below.

＜Mole ratio of Mn and content of bismuth＞ The manganese concentration and bismuth content of the red phosphors of Examples 1-7 and Comparative Example 1 were measured by energy dispersive X-ray spectrometry (EDX). The so-called EDX measurement is a measurement method that measures the fluorescent X-rays generated when X-rays are irradiated on a sample, and analyzes the elements and concentrations that constitute the sample.

Each of the red phosphors of Examples 1 to 7 and Comparative Example 1 was placed on the sample stand of the EDX measuring device, and the manganese concentration and the bismuth content were calculated. As the EDX measuring device, a JSF-7800F Schottky field emission scanning electron microscope (trade name, manufactured by JEOL Ltd.) was used. In addition, the measurement conditions were set as acceleration voltage: 15 kV, irradiation current: 1.0000 nA, and energy range: 0-20 keV.

As a result of the measurement, the molar ratio of Mn to the total molar ratio of Si and Mn in the red phosphor (Mn/(Si+Mn)), when the red phosphors of Examples 1 to 7, are respectively 0.054 , 0.054, 0.055, 0.054, 0.054, 0.055, 0.055, 0.055 in the case of the red phosphor of Comparative Example 1.

In addition, when the content of bismuth is the red phosphor of Examples 1-7, they are 4.1wt%, 1.3wt%, 0.4wt%, 10.7wt%, 14.9wt%, 4.0wt%, 0.4wt%, respectively, for comparison For the red phosphor of Example 1, it is below the detection limit (0.01wt%).

＜Evaluation of the optical properties of red phosphors＞ In order to evaluate the optical properties of the red phosphors of Examples 1-7 and Comparative Example 1, the individual absorptivity and internal quantum efficiency were calculated.

Absorbance and internal quantum efficiency are measured using blue LED concentrating lighting (trade name: TSPA22X8-57B, manufactured by AS ONE) and a spectroradiometer (trade name: SR-UL2, manufactured by TOPCON). _{That is, a white board (BaSO 4} , manufactured by JASCO Corporation) that reflects almost 100% of the excitation light is set on the sample table, the spectral emission brightness of the excitation light (wavelength: 449 nm) is measured, and the peak value (Ex1) is calculated.

Next, add samples of any one of the red phosphors in Examples 1 to 7 or Comparative Example 1 to the concave portion of the sample table, and measure the spectral emission brightness peak (Em) of the fluorescence under excitation light irradiation, and the Excitation light peak of absorption component (Ex2).

The absorptivity α of each of the red phosphors of Examples 1 to 7 and Comparative Example 1 was calculated using the following formula (1). The results are shown in Table 1. Absorption rate α(%)=(Ex1-Ex2)/Ex1×100 (1)

In addition, the internal quantum efficiency η of each of the red phosphors of Examples 1 to 7 and Comparative Example 1 was calculated using the following equation (2). The results are shown in Table 1. Internal quantum efficiency η(%)=Em/(Ex1-Ex2)×100 (2)

＜Evaluation of the durability of red phosphor＞ The durability test was performed as follows. First, 0.3 g of the red phosphors of Examples 1 to 7 or Comparative Example 1 were put into a PFA tray, set and controlled at a temperature of 80°C and a relative humidity of 80% in a thermohygrostat, and stored for 88 hours. Then, by the aforementioned method, the absorption rate α and the internal quantum efficiency η are respectively obtained. Furthermore, under an environment with a temperature of 80° C. and a relative humidity of 80%, the absorption rate α and the internal quantum efficiency η of each red phosphor after being stored for 168 hours were also determined.

Furthermore, according to the following formula (3), from the value of the internal quantum efficiency before and after the durability test of each red phosphor, an index of durability under the high temperature and high humidity environment of the red phosphor is calculated. The results are shown in Table 1. (Durability index) = (Internal quantum efficiency after endurance test)/(Endurance test Internal quantum efficiency before)×100 (3) In addition, the "after endurance test" in the formula (3) means the condition after storage for 88 hours and the condition after storage for 168 hours in an environment with a temperature of 80°C and a relative humidity of 80%.

(result) As shown in Table 1, in the red phosphors of Examples 1 to 7 that were surface-treated with a treatment solution containing bismuth fluoride, the content of bismuth was confirmed. In addition, the red phosphors of Examples 1 to 7 are considered to have improved durability in a high temperature and high humidity environment compared with the red phosphor of Comparative Example 1 which has not been surface-treated.

Claims (13)

A red phosphor, which contains Mn activated bisfluoride represented by the following general formula (1), and bismuth, A ₂ MF ₆ : Mn ⁴⁺ (1) (In the formula, the aforementioned A series means selected from lithium, At least one alkali metal element from the group consisting of sodium, potassium, rubidium, and cesium. The aforementioned M represents at least one element selected from the group consisting of silicon, germanium, tin, titanium, zirconium, and hafnium 4-valent element). The red phosphor according to claim 1, wherein the Mn-activated bisfluoride is in a particulate form, and the bismuth is present on at least a part of the surface of the particulate Mn-activated bisfluoride. The red phosphor as described in claim 2, wherein a coating layer is provided on the surface of the aforementioned particulate Mn activated bisfluoride, The coating layer contains the bismuth. The red phosphor according to claim 3, wherein the coating layer contains bismuth monomer and/or bismuth compound. The red phosphor according to claim 4, wherein the bismuth compound is selected from BiF ₃ , BiCl ₃ , BiBr ₃ , _{BiI 3} , Bi ₂ O ₃ , Bi ₂ S ₃ , Bi ₂ Se ₃ , BiSb, Bi ₂ Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ At least one of the group consisting of H ₁₀ BiK ₃ O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi and C ₆ H ₄ (OH)CO ₂ BiO･H _{2 O.} The red phosphor according to claim 1, wherein the content of bismuth is in the range of 0.01% by mass to 15% by mass relative to the total mass of the red phosphor. The red phosphor according to claim 1, wherein the molar ratio of the Mn in the Mn-activated difluoride is in the range of 0.005 to 0.15 relative to the total molar of the M and Mn. A method for manufacturing a red phosphor, which includes the step of contacting the Mn-activated bisfluoride represented by the following general formula (1) with a treatment solution containing bismuth, A ₂ MF ₆ : Mn ⁴⁺ (1) (Formula Wherein, the aforementioned A series means at least one alkali metal element selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, and the aforementioned M series means selected from the group consisting of silicon, germanium, tin, titanium, zirconium and hafnium. At least one tetravalent element in the group). The method for producing a red phosphor according to claim 8, wherein the content of the bismuth in the treatment liquid is in the range of 0.01% by mass to 15% by mass relative to the total mass of the treatment liquid. The method for producing a red phosphor according to claim 8, wherein the solvent of the treatment liquid is water, an organic solvent, a mixed solvent of these, or an acidic solvent of these. The method for producing a red phosphor according to claim 10, wherein the acidic solvent is an acidic solvent containing hydrogen fluoride, The mixing ratio of the acidic solvent containing the hydrogen fluoride and the bismuth is in the range of 30:1 to 3500:1 on a mass basis. The method for producing a red phosphor according to claim 11, wherein the concentration of the hydrogen fluoride in the acidic solvent containing hydrogen fluoride is in the range of 1% by mass to 70% by mass relative to the total mass of the acidic solvent. The method for producing a red phosphor according to claim 8, wherein the aforementioned bismuth is selected from Bi monomer, BiF ₃ , BiCl ₃ , BiBr ₃ , _{BiI 3} , Bi ₂ O ₃ , Bi ₂ S ₃ , Bi ₂ Se ₃ , BiSb, Bi ₂ Te ₃ , Bi(OH) ₃ , (BiO) ₂ CO ₃ , BiOCl, BiPO ₄ , Bi ₂ Ti ₂ O ₇ , Bi(WO ₄ ) ₃ , Bi ₂ (SO ₄ ) ₃ , BiOCH ₃ COO, 4BiNO ₃ (OH) ₂ ･BiO(OH), C ₃ F ₉ O ₉ S ₃ Bi, C ₇ H ₇ BiO ₇ , C ₉ H ₂₁ BiO ₃ , C ₁₅ H ₃₃ BiO ₃ , C ₃₀ H ₅₇ BiO ₆ , C ₁₂ H ₁₀ BiK ₃ O ₁₄ , C ₃ F ₉ O ₉ S ₃ Bi and C ₆ H ₄ (OH)CO ₂ BiO･H ₂ O form at least one of the group, included in In the aforementioned treatment solution.