JP6066003B2 - Fluoride phosphor, method for producing the same, and light emitting device - Google Patents

Description

  The present disclosure relates to a fluoride phosphor, a manufacturing method thereof, and a light emitting device.

  A light emitting diode (LED) is a semiconductor light emitting element (hereinafter also referred to as “light emitting element”) produced from a metal compound such as gallium nitride (GaN). Various light emitting devices that emit light in white, light bulb color, orange color, etc. by combining the semiconductor light emitting element and the phosphor have been developed. These light emitting devices that emit white light and the like are obtained by the principle of light color mixing. As a method for emitting white light, a method using a light emitting element that emits ultraviolet light and three kinds of phosphors that emit red, green, and blue, a light emitting element that emits blue light, and a yellow light emitting element are used. A method using a phosphor is well known. A light-emitting device using a light-emitting element that emits blue light and a phosphor that emits yellow light or the like is required in a wide range of fields such as general lighting, liquid crystal backlights, in-vehicle lighting, and displays.

For example, as a red-emitting phosphor having an excitation band in the blue region and a narrow half-value width of the emission peak, for example, a fluoride phosphor having a composition of K ₂ SiF ₆ : Mn ⁴⁺ is known, and the production thereof Various improvements of the method have been studied (for example, see Patent Document 1).

JP 2012-224536 A

The red light emitting Mn ⁴⁺ activated fluoride phosphor with a narrow half-value width of the emission peak is desired to be put to practical use. However, there is room for improvement in the durability of the conventional technology, so that it can be used in harsh environments such as lighting applications. It was insufficient for use.
In light of the above, an object of one embodiment of the present disclosure is to provide a red-emitting phosphor excellent in durability and a method for manufacturing the same.

Specific means for solving the above problems are as follows, and the present disclosure includes the following aspects.
The first embodiment includes a particle having a composition represented by the following formula (I), IR peak area ratio Z ¹ given in the infrared absorption spectrum by the following formula (P) is 2.5 × 10 below ^-3 This is a fluoride phosphor.
A ₂ [M _1-a Mn ⁴⁺ _a F ₆ ] (I)
In the formula, A represents at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M represents a group 4 element and a group 14 element. It represents at least one element selected from the group consisting of group elements, and a satisfies 0.01 <a <0.20.
Z ¹ = (3500cm ^-1 or 3800 cm ^-1 The following peak areas) / (1050 cm ^-1 or 1350 cm ^-1 The following peak areas) (P)

The second aspect includes a first solution containing manganese, a second solution containing at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ . Preparing a solution and a third solution containing at least one element selected from the group consisting of a group 4 element and a group 14 element; and preparing the prepared first solution and third solution Dropping each of the prepared liquids at a drop rate per minute of 0.3% by volume or less into the prepared second solution to obtain particles having a composition represented by the following formula (I): And a method for producing a fluoride phosphor, comprising heat-treating a mixture of the obtained particles and a liquid medium containing elemental fluorine.
A ₂ [M _1-a Mn ⁴⁺ _a F ₆ ] (I)
In the formula, A represents at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M represents a group 4 element and a group 14 element. It represents at least one element selected from the group consisting of group elements, and a satisfies 0.01 <a <0.20.

  According to an embodiment of the present disclosure, it is possible to provide a red-emitting phosphor excellent in durability and a method for manufacturing the same.

It is a schematic sectional drawing which shows an example of the light-emitting device which concerns on this embodiment. It is a figure which shows an example of the infrared absorption spectrum of the fluoride fluorescent substance which concerns on this embodiment, and the infrared absorption spectrum for the comparison with it. It is a figure which expands and shows a part of infrared absorption spectrum of the fluoride fluorescent substance which concerns on this embodiment shown by FIG.

Hereinafter, a fluoride fluorescent substance, a manufacturing method thereof, and a light emitting device according to the present disclosure will be described using embodiments and examples. However, the embodiment described below exemplifies a fluoride phosphor, a manufacturing method thereof, and a light-emitting device for embodying the technical idea of the present invention. The manufacturing method and the light emitting device are not specified as follows.
The relationship between the color name and the chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, and the like comply with JIS Z8110. Specifically, 380 nm to 410 nm is purple, 410 nm to 455 nm is blue purple, 455 nm to 485 nm is blue, 485 nm to 495 nm is blue green, 495 nm to 548 nm is green, 548 nm to 573 nm is yellow green, 573 nm to 584 nm is yellow, 584 nm to 610 nm is yellowish red, and 610 nm to 780 nm is red. In this specification, the light in the short wavelength region of visible light is not particularly limited, but refers to a region of 400 nm to 500 nm.

  In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

<Fluoride phosphor>
The fluoride fluorescent material of the present embodiment has a composition represented by the following formula (I), and an IR peak area ratio Z ¹ given by the following formula (P) in the infrared absorption spectrum is 2.5 × 10 ⁻ Less than ³ .
A ₂ [M _1-a Mn ⁴⁺ _a F ₆ ] (I)
In the formula, A represents at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M represents a group 4 element and a group 14 element. It represents at least one element selected from the group consisting of group elements, and a satisfies 0.01 <a <0.20.
Z ¹ = (3500cm ^-1 or 3800 cm ^-1 The following peak areas) / (1050 cm ^-1 or 1350 cm ^-1 The following peak areas) (P)

FIG. 2 is a diagram showing an example of an infrared absorption spectrum of the fluoride phosphor according to the present embodiment and an infrared absorption spectrum for comparison with the example. 3, of the infrared absorption spectrum shown in FIG. 2 is an enlarged view showing wave number enlarged portion of 3900Cm ^-1 from 3000 cm ^-1. In the infrared absorption spectrum of the fluoride phosphor, the peak area of 3500 cm ^-1 or 3800 cm ^-1 The following wavenumber range, IR peak area ratio is an area ratio to the peak area of 1050 cm ^-1 or 1350 cm ^-1 following wavenumber range Z ¹ is smaller than 2.5 × 10 ⁻³ . Thereby, a fluoride phosphor having excellent durability can be obtained. Moreover, the light-emitting device comprised using this fluoride fluorescent substance can show the outstanding long-term reliability. Here 1050 cm ^-1 or 1350 cm ^-1 or less absorption is the absorption derived from a fluoride phosphor itself, absorption of 3000 cm ^-1 or 3800 cm ^-1 or less, for example, an absorption derived from water _(H 2 O) There, the absorption of 3500 cm ^-1 or 3800 cm ^-1 or less, for example, an absorption derived from the silanol residue (Si-OH). That is, the IR peak area ratio Z ¹ being 2.5 × 10 ⁻³ or less means that the amount of the component due to OH contained in the fluoride fluorescent material is small. Such a fluoride fluorescent substance is considered to have particularly reduced crystal defects and the like on the surface thereof, and is considered to be excellent in durability.

In the fluoride phosphor, the IR peak area ratio Z ¹ is preferably 1.0 × 10 ⁻³ or less from the viewpoint of durability.
Further, the lower limit of the IR peak area ratio Z ¹ is not particularly limited, and can be appropriately selected depending on the purpose and the like. For example, the IR peak area ratio Z ¹ is larger than 0 and 1.0 × 10 ⁻⁵ or more. preferable. Z ¹ is 0 and greater than, for example, hydrophilicity is imparted to the surface of the fluoride phosphor particles tend to disperse in the resin is improved, the flow of the uncured resin composition comprising a fluoride phosphor Tend to be more improved.

The infrared absorption spectrum of the fluoride phosphor is measured by a diffuse reflection method with a potassium bromide (KBr) background. Peak area of 3500 cm ^-1 or 3800 cm ^-1 The following wavenumber ranges are calculated a straight line connecting the absorption intensity in the absorption intensity and the 3800 cm ^-1 in 3000 cm ^-1 as a background. The peak area in the wave number range of 1050 cm ^{−1 to} 1350 cm ⁻¹ is calculated with a straight line connecting absorption intensities at both ends of the integration range as the background. For example, the specific area can be calculated by software attached to the infrared spectrometer.

The fluoride phosphor includes particles having a composition represented by the formula (I). A in the formula (I) is lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium ion (Rb ⁺ ), cesium ion (Cs ⁺ ) and ammonium ion (NH ₄ ⁺ ). At least one cation selected from the group consisting of: Among them A ^{is, Li +, Na +, K} +, Rb +, is selected from Cs ⁺ and the group consisting of _NH ^{4 +,} is preferably at least one cation containing ^{K +,} mainly containing ^{K +} More preferred is a cation such as an alkali metal. Here, “having K ⁺ as the main component” means that the content of K ⁺ in A of formula (I) is 80 mol% or more, preferably 90 mol% or more, and 95 mol % Or more is more preferable.

M in the formula (I) is at least one selected from the group consisting of Group 4 elements and Group 14 elements, and M is titanium (Ti), zirconium (Zr), hafnium from the viewpoint of light emission characteristics. It is preferably at least one selected from the group consisting of (Hf), silicon (Si), germanium (Ge) and tin (Sn), and silicon (Si) or silicon (Si) and germanium (Ge) More preferably, silicon (Si), or silicon (Si) and germanium (Ge) are more preferable.
When M includes silicon (Si), or silicon (Si) and germanium (Ge), a part of at least one of Si and Ge includes a Group 4 element including Ti, Zr, and Hf, and C and Sn It may be substituted with at least one selected from the group consisting of Group 14 elements. In that case, the total content of Si and Ge in M is not particularly limited, and is preferably 90 mol% or more, and more preferably 95 mol% or more, for example.

  A in the formula (I) is 0.01 or more and 0.20 or less, preferably 0.015 or more and 0.15 or less, more preferably 0.02 or more and 0.10 or less, from the viewpoint of light emission efficiency and light emission intensity. More preferably, it is 0.03 or more and 0.10 or less.

  The particle size and particle size distribution of the fluoride phosphor are not particularly limited, and preferably have a single peak particle size distribution from the viewpoint of light emission intensity and durability, and be a single peak particle size distribution with a narrow distribution width. Is more preferable. The particle size of the fluoride particles is, for example, 1 μm or more and 100 μm or less as a volume average particle size, preferably 5 μm or more and 70 μm or less, and more preferably 20 μm or more and 70 μm or less. Further, the surface area and bulk density of the fluoride phosphor are not particularly limited. The volume average particle diameter of the fluoride particles is a particle diameter (median diameter) measured by a laser diffraction particle size distribution measuring device (MASTER SIZER 2000 manufactured by MALVERN).

The fluoride phosphor is a phosphor activated by Mn ⁴⁺ and can absorb red light in the short wavelength region of visible light and emit red light. The excitation light that is light in the short wavelength region of visible light is preferably mainly light in the blue region. Specifically, the excitation light preferably has a main peak wavelength of an intensity spectrum in the range of 380 nm to 500 nm, more preferably in the range of 380 nm to 485 nm, and in the range of 400 nm to 485 nm. More preferably, it exists, and it is especially preferable that it exists in the range of 440 nm or more and 480 nm or less.

  The emission wavelength of fluoride is not particularly limited as long as it is longer than the excitation light and is red. The emission spectrum of fluoride preferably has a peak wavelength in the range of 610 nm to 650 nm. The half width of the emission spectrum is preferably small, specifically 10 nm or less.

<Method for producing fluoride phosphor>
In the method for producing a fluoride phosphor of the present embodiment, particles having a composition represented by formula (I) (hereinafter also referred to as “fluoride particles”) are heated at 100 ° C. or higher in an atmosphere containing fluorine element. Including processing. Fluoride particles can be produced by a commonly used method. Moreover, it can also manufacture with the manufacturing method mentioned later.
By heat-treating the fluoride particles at 100 ° C. or higher in an atmosphere containing fluorine atoms, for example, the content of hydroxyl groups, silanol residues, etc. present on the surface of the fluoride particles is reduced, thereby improving durability. It is thought to improve.

  The atmosphere containing fluorine element may be liquid or gas, and is preferably liquid. When the atmosphere containing a fluorine element is a liquid, for example, a liquid medium containing a fluorine compound such as hydrogen fluoride can be used. Moreover, when the atmosphere containing a fluorine element is gas, it can be set as gas containing fluorine compounds, such as hydrogen fluoride, fluorine gas, etc., for example.

When the atmosphere containing fluorine element is liquid, examples of the liquid medium include organic solvents such as water, alcohol solvents such as methanol, ethanol and isopropyl alcohol, ketone solvents such as acetone and methyl ethyl ketone, and ether solvents such as diethyl ether and diisopropyl ether. Mention may be made of solvents. Examples of the fluorine compound include inorganic acid salts such as hydrogen fluoride (HF), hexafluorosilicic acid (H ₂ SiF ₆ ), potassium hydrogen fluoride (KHF ₂ ), and potassium fluoride (KF). Can do. The fluorine compound contained in the liquid medium may be a single type or a combination of two or more types.
The atmosphere containing fluorine element may further contain components other than the fluorine compound. Examples of components other than the fluorine compound include inorganic acids such as nitric acid (HNO ₃ ); peroxides such as hydrogen peroxide; inorganic acid salts containing potassium ions such as potassium nitrate (KNO ₃ ). Among them, the component other than the fluorine compound preferably contains at least potassium ion, and more preferably contains at least an inorganic acid salt containing potassium ion. Components other than the fluorine compound may be used alone or in combination of two or more.

  The concentration of the fluorine compound in the liquid medium containing the fluorine compound is not particularly limited, and may be appropriately selected depending on the purpose and the like. For example, when the liquid medium contains hydrogen fluoride, the concentration of hydrogen fluoride can be 30 to 60% by mass, and preferably 45 to 60% by mass. Moreover, when a liquid medium contains fluoride salts, such as potassium hydrogen fluoride, the density | concentration can be 10-25 mass%, and 15-20 mass% is preferable.

When the atmosphere containing a fluorine element is a gas, a gas medium other than fluorine gas or a fluorine compound may be included. Examples of the gas medium include nitrogen (N ₂ ), argon (Ar), oxygen (O ₂ ), and the like. Among these, an inert atmosphere such as nitrogen is preferable from the viewpoint of suppressing oxidation of the fluoride phosphor. The components of the gas medium may be used alone or in combination of two or more.

  When the atmosphere containing elemental fluorine is a gas, the concentration of fluorine gas or fluorine compound can be, for example, 10% by volume or more, and preferably 15% by volume or more.

The temperature of the heat treatment is 100 ° C. or higher, preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and further preferably 150 ° C. or higher. The upper limit of the temperature is not particularly limited, and is preferably 600 ° C. or less and more preferably 550 ° C. or less from the viewpoint of durability and production efficiency.
Moreover, it is preferable that a heat processing is performed in a liquid medium from a viewpoint of a durable improvement and a dispersibility improvement.

  The heat treatment may be performed under pressurized conditions. The pressure condition in the case of pressurization is not particularly limited and can be appropriately selected according to the purpose and the like. Since vaporization occurs during the heat treatment with a liquid, the heat treatment can be performed in a sealed atmosphere. In this case, the pressure is preferably 1.5 MPa or more and more preferably 2.5 MPa or more from the viewpoint of improving durability. The upper limit of the pressure is not particularly limited, and is preferably 30 MPa or less and more preferably 15 MPa or less from the viewpoint of durability and production efficiency. In the heat treatment with a gas medium, the pressure is preferably from atmospheric pressure to 1 MPa or less.

  The heat treatment time may be appropriately selected depending on conditions such as the amount of treatment and temperature. For example, the treatment time is preferably 1 hour or longer, more preferably 2 hours or longer from the viewpoint of improving durability. The upper limit of the treatment time is not particularly limited, and is preferably 48 hours or less, more preferably 24 hours or less from the viewpoint of durability and production efficiency.

The fluoride particles include, for example, a first solution containing manganese, a second solution containing at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ . And a third solution containing at least one element selected from the group consisting of a group 4 element and a group 14 element, and the prepared first solution and third solution, Each of the prepared liquid amounts is added to the prepared second solution at a dropping amount per minute that is 0.3% by volume or less to obtain fluoride particles. It is preferable.
Fluoride particles produced by such a production method tend to improve the internal quantum efficiency of fluorescence. The internal quantum efficiency is, for example, 80% or more, and preferably 85% or more.

Fluoride phosphor particles formed by dropping the first solution and the third solution into the second solution at a drop amount per minute of 0.3% by volume or less of the initial solution amount. While increasing the amount of manganese contained, a fluoride phosphor excellent in internal quantum efficiency can be obtained. This is because, for example, the production reaction of the fluoride phosphor proceeds sufficiently controlled to make the distribution of manganese in the fluoride phosphor particles more uniform, and crystals near Mn ⁴⁺ that activate the fluoride phosphor. It can be considered that the structure is stabilized or the crystal defects in the fluoride phosphor are reduced. In addition, the obtained phosphor is considered to have a high reflectance at a wavelength of 530 nm. For example, when applied to a lighting application together with a green-emitting phosphor, a decrease in luminance in the green region can be suppressed.

In the dropping step, the first solution and the third solution are dropped at a dropping amount per minute of 0.3% by volume or less of each initial liquid amount. That is, the first solution and the third solution are added dropwise over 333.3 minutes (5.6 hours). The amount of each solution dropped per minute is preferably 0.1% by volume or less of the initial liquid amount.
The dropping time of the first solution and the dropping time of the third solution are appropriately selected according to the amount of liquid prepared, etc., and may be the same or different, and are preferably the same.

In the dropping step, it is preferable to drop the first solution and the third solution while stirring the second solution. The stirring method is not particularly limited, and can be appropriately selected from commonly used stirring methods according to the production scale, reaction kettle, and the like.
Moreover, the temperature in the dropping step is not particularly limited. For example, what is necessary is just to control so that the temperature of a 2nd solution may be 40 degrees C or less, and it is preferable to control so that it may become 15-30 degreeC.

The first solution contains at least a first complex ion containing tetravalent manganese and hydrogen fluoride, and may contain other components as necessary. The first solution is obtained, for example, as an aqueous solution of hydrofluoric acid containing a manganese source. The manganese source is not particularly limited as long as it is a compound containing manganese. Specific examples of the manganese source that can constitute the first solution include K ₂ MnF ₆ , KMnO ₄ , and K ₂ MnCl ₆ . Among these, K ₂ MnF ₆ is preferable because it can be stably present in hydrofluoric acid as a MnF ₆ complex ion while maintaining the oxidation number (tetravalent) that can be activated. Of the manganese sources, those containing an alkali metal such as potassium can also serve as part of a cation source such as an alkali metal contained in the second solution. Manganese sources constituting the first solution may be used alone or in combination of two or more.

The lower limit of the hydrogen fluoride concentration in the first solution is usually 20% by mass or more, preferably 25% by mass or more, and more preferably 30% by mass or more. Moreover, the upper limit of the hydrogen fluoride concentration in the first solution is usually 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less. When the hydrogen fluoride concentration is 30% by mass or more, the stability of the manganese source (for example, K ₂ MnF ₆ ) constituting the first solution to hydrolysis is improved, and the tetravalent manganese concentration in the first solution is increased. Fluctuations are suppressed. As a result, the amount of manganese activation contained in the resulting fluoride phosphor can be easily controlled, and variations in the luminous efficiency of the fluoride phosphor tend to be suppressed. Moreover, when the hydrogen fluoride concentration is 70% by mass or less, the lowering of the boiling point of the first solution is suppressed, and the generation of hydrogen fluoride gas is suppressed. Thereby, the hydrogen fluoride concentration in the first solution can be easily controlled, and the variation (variation) in the particle diameter of the obtained fluoride phosphor can be effectively suppressed.

  The manganese source concentration in the first solution is not particularly limited. The lower limit value of the manganese source concentration in the first solution is usually 0.01% by mass or more, preferably 0.03% by mass or more, more preferably 0.05% by mass or more. Moreover, the upper limit of the manganese source concentration in the first solution is usually 50% by mass or less, preferably 40% by mass or less, and more preferably 30% by mass or less.

The second solution preferably contains at least potassium. Second ^{solution, K +, Li +, Na} +, Rb +, is selected from Cs ⁺ and the group consisting of _NH ^{4 +,} wherein at least at least one cation containing ^{K +,} and hydrogen fluoride Other components may be included as necessary. The second solution is obtained, for example, as an aqueous solution of hydrofluoric acid containing alkali metal ions such as potassium ions. Specific examples of potassium sources containing potassium ions that can constitute the second solution include water-soluble potassium salts such as KF, KHF ₂ , KOH, KCl, KBr, KI, potassium acetate, and K ₂ CO _3. Can do. Among these, KHF ₂ is preferable because it can be dissolved without lowering the concentration of hydrogen fluoride in the solution, and the heat of dissolution is small and the safety is high. Examples of the cation source such as alkali metal other than the potassium source include NaHF ₂ , Rb ₂ CO ₃ , Cs ₂ CO _{3 and the} like. The cation source constituting the second solution may be used alone or in combination of two or more.

The lower limit of the hydrogen fluoride concentration in the second solution is usually 20% by mass or more, preferably 25% by mass or more, more preferably 30% by mass or more. Moreover, the upper limit of the hydrogen fluoride concentration in the second solution is usually 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less.
Moreover, the lower limit of the cation source concentration in the second solution is usually 5% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more. Moreover, the upper limit of the alkali metal source concentration in the second solution is usually 80% by mass or less, preferably 70% by mass or less, and more preferably 60% by mass or less.

The third solution includes at least a second complex ion including at least one selected from the group consisting of Group 4 elements and Group 14 elements and fluorine ions, and optionally includes other components. You may go out. The third solution is obtained, for example, as an aqueous solution containing the second complex ion.
The second complex ion includes at least one selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), silicon (Si), germanium (Ge), and tin (Sn). Preferably, silicon (Si) or silicon (Si) and germanium (Ge) are more preferably contained, and a silicon fluoride complex ion is further preferred.

For example, when the second complex ion includes silicon (Si), the second complex ion source is preferably a compound that includes silicon and fluorine and has excellent solubility in a solution. Specific examples of the second complex ion source include H ₂ SiF ₆ , Na ₂ SiF ₆ , (NH ₄ ) ₂ SiF ₆ , Rb ₂ SiF ₆ , and Cs ₂ SiF ₆ . Among these, H ₂ SiF ₆ is preferable because it has high solubility in water and does not contain an alkali metal element as an impurity. The second complex ion source constituting the third solution may be used alone or in combination of two or more.

  The lower limit of the second complex ion source concentration in the third solution is usually 5% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more. Moreover, the upper limit of the 2nd complex ion source density | concentration in a 3rd solution is 80 mass% or less normally, Preferably it is 70 mass% or less, More preferably, it is 60 mass% or less.

  The first solution and the third solution are dropped into the second solution at a predetermined amount per unit time and mixed to obtain a first complex ion and an alkali metal ion or the like at a predetermined ratio. The fluoride phosphor, which is a crystal having the chemical composition represented by the target formula (I), reacts with the ions and the second complex ions. The deposited fluoride phosphor can be recovered by solid-liquid separation by filtration or the like. Moreover, you may wash | clean with solvents, such as ethanol, isopropyl alcohol, water, and acetone. Further, a drying treatment may be performed, and drying is usually performed at 50 ° C. or higher, preferably 55 ° C. or higher, more preferably 60 ° C. or higher, and usually 150 ° C. or lower, preferably 120 ° C. or lower, more preferably 110 ° C. or lower. The drying time is not particularly limited as long as the water adhering to the fluoride phosphor can be evaporated, and is, for example, about 10 hours.

  In mixing the first solution, the second solution, and the third solution, the difference between the charged composition of the first to third solutions and the chemical composition of the obtained fluoride phosphor is taken into consideration. It is preferable to appropriately adjust the mixing ratio of the first solution, the second solution, and the third solution so that the chemical composition of the fluoride phosphor as a product has the target chemical composition.

  In addition to the above, the method for producing a fluoride phosphor may further include post-treatment steps such as separation treatment, purification treatment, and drying treatment of the fluoride phosphor.

<Light emitting device>
The light emitting device of the present embodiment absorbs light in the wavelength range of 380 nm to 485 nm, the excitation light source that emits light in the wavelength range of 380 nm to 485 nm, the first phosphor including the fluoride phosphor, And a second phosphor having a maximum emission wavelength in a wavelength range of 495 nm or more and 590 nm or less. The light emitting device may further include other components as necessary. When the light-emitting device contains the fluoride phosphor, the durability is excellent and excellent long-term reliability can be achieved. That is, the light-emitting device including the fluoride fluorescent material can be suitably applied to use in a harsh environment such as an illumination application because a decrease in output and a change in chromaticity are suppressed over a long period of time.

(Excitation light source)
As the excitation light source, a light source that emits light in a wavelength range of 380 nm to 485 nm, which is a short wavelength region of visible light, is used. The excitation light source preferably has an emission peak wavelength (maximum emission wavelength) in a wavelength range of 420 nm to 485 nm, more preferably in a wavelength range of 440 nm to 480 nm. Thereby, a fluoride fluorescent substance can be excited efficiently and visible light can be used effectively. In addition, a light-emitting device with high emission intensity can be provided by using an excitation light source in the wavelength range.

A semiconductor light emitting element is preferably used as the excitation light source. By using a semiconductor light emitting element as the excitation light source, a stable light emitting device with high efficiency, high output linearity with respect to input, and strong against mechanical shock can be obtained.
A light emitting element that emits light in a short wavelength region of visible light can be used. For example, the blue, the green light emitting element, can be used using a nitride-based semiconductor _{(In X Al Y Ga 1-} X-Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1).

(First phosphor)
The first phosphor included in the light emitting device includes the aforementioned fluoride phosphor. Details of the fluoride phosphor are as described above. For example, a fluoride phosphor can be included in a sealing resin that covers an excitation light source to constitute a light emitting device. In the light emitting device in which the excitation light source is covered with the sealing resin containing the fluoride phosphor, a part of the light emitted from the excitation light source is absorbed by the fluoride phosphor and emitted as red light. By using an excitation light source that emits light in a wavelength range of 380 nm or more and 485 nm or less, emitted light can be used more effectively. Therefore, loss of light emitted from the light emitting device can be reduced, and a highly efficient light emitting device can be provided.
The content of the fluoride phosphor contained in the light emitting device is not particularly limited and can be appropriately selected according to the excitation light source and the like.

(Second phosphor)
In addition to the first phosphor, the light emitting device further includes another phosphor that absorbs light in a wavelength range of 380 nm to 485 nm and has a maximum emission wavelength in a wavelength range of 495 nm to 590 nm. When the light emitting device includes the second phosphor, it can be more suitably applied as a lighting device. Other phosphors can be included in a sealing resin in the same manner as the fluoride phosphor, for example, to constitute a light emitting device.

  Examples of the second phosphor include nitride phosphors, oxynitride phosphors, sialon phosphors mainly activated by lanthanoid elements such as Eu and Ce; lanthanoid compounds such as Eu, Mn, and the like Alkaline earth halogen apatite phosphors, alkaline earth metal borate phosphors, alkaline earth metal aluminate phosphors, alkaline earth silicates, alkaline earths mainly activated by transition metal elements of Sulfides, alkaline earth thiogallates, alkaline earth silicon nitrides, germanates; rare earth aluminates, rare earth silicates mainly activated by lanthanoid elements such as Ce; and lanthanoid elements such as Eu It is preferably at least one selected from the group consisting of organic and organic complexes that are mainly activated.

The second phosphor is represented by a β sialon phosphor having a composition represented by the following formula (IIa), a halosilicate phosphor having a composition represented by the following formula (IIb), and the following formula (IIc). At least selected from the group consisting of a silicate phosphor having a composition, a rare earth aluminate phosphor having a composition represented by the following formula (IId), and a sulfide phosphor having a composition represented by the following formula (IIe) One type is preferable.
Si _6-t Al _t O _t N _8-t : Eu (IIa)
(In the formula, t satisfies 0 <t <4.2.)
(Ca, Sr, Ba) ₈ MgSi ₄ O ₁₆ (F, Cl, Br) ₂ : Eu (IIb)
(Ba, Sr, Ca, Mg) ₂ SiO ₄ : Eu (IIc)
(Y, Lu, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (IId)
(Ba, Sr, Ca) Ga ₂ S ₄ : Eu (IIe)
A 2nd fluorescent substance may be used individually by 1 type, and may use 2 or more types together.

The light emitting device may further include other phosphors in addition to the first phosphor and the second phosphor. Other phosphors include, for example, Sr ₄ Al ₁₄ O ₂₅ : Eu, (Ba, Sr, Ca) Si ₂ O ₂ N ₂ : Eu, (La, Y) ₃ Si ₆ N ₁₁ : Ce, Ca ₃ Sc _{2 Si 3 O 12: Ce,} CaSc 2 O 4: Ce, Ba 3 Si 6 O 12 N 2: Eu, (Sr, Ca) AlSiN 3: Eu, (Ca, Sr, Ba,) 2 Si 5 N 8: Eu, 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn, and the like can be given. Other phosphors may be used alone or in combination of two or more.

The first phosphor and the second phosphor (hereinafter, also simply referred to as “phosphor”) preferably constitute a sealing material that seals the light emitting element together with the binder. Examples of the binder constituting the sealing material include thermosetting resins such as epoxy resins, silicone resins, epoxy-modified silicone resins, and modified silicone resins.
The total content of the phosphor in the sealing material is not particularly limited and can be appropriately selected depending on the purpose and the like. The total content of the phosphor can be, for example, 20 to 300 parts by mass with respect to 100 parts by mass of the binder, preferably 25 to 200 parts by mass, more preferably 30 to 160 parts by mass. Part by mass is more preferable. When the content of the phosphor in the sealing material is in the above range, the light emitting element can be sufficiently covered, and the light emitted from the light emitting element can be efficiently wavelength-converted by the phosphor, and more efficiently. Can emit light.

  The mass-based content ratio (second phosphor: first phosphor) of the second phosphor to the first phosphor in the light emitting device is, for example, 5:95 to 95: 5, preferably 10: 90-90: 10, More preferably, it is 15: 85-85: 15, More preferably, it is 20: 80-80: 20. When the light emitting device includes the first phosphor and the second phosphor in the above range, a light emitting device having higher color rendering and more excellent emission intensity can be obtained.

The sealing material may further contain a filler, a diffusing material and the like in addition to the binder and the phosphor. Examples of the filler include silica, titanium oxide, zinc oxide, zirconium oxide, and alumina.
When the sealing material contains a filler, the content can be appropriately selected according to the purpose and the like. The filler content can be, for example, 1 to 20 parts by mass with respect to 100 parts by mass of the binder.

  The form of the light emitting device is not particularly limited, and can be appropriately selected from commonly used forms. As a type of the light emitting device, a shell type, a surface mount type, and the like can be given. In general, the bullet shape refers to a shape in which the shape of the resin constituting the outer surface is formed into a bullet shape. In addition, the surface mount type refers to a product formed by filling a light emitting element serving as an excitation light source and a resin in a concave storage portion. Further, as a type of light emitting device, a light emitting device in which a light emitting element serving as an excitation light source is mounted on a flat mounting substrate, and a sealing resin containing a phosphor is formed in a lens shape or the like so as to cover the light emitting device. And so on.

Hereinafter, an example of the light emitting device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light emitting device according to this embodiment. This light-emitting device is an example of a surface-mounted light-emitting device.
The light emitting device 100 includes a light emitting element 10 of a gallium nitride compound semiconductor that emits light on a short wavelength side of visible light (for example, 380 nm to 485 nm), and a molded body 40 on which the light emitting element 10 is mounted. The molded body 40 has a first lead 20 and a second lead 30 and is integrally formed of a thermoplastic resin or a thermosetting resin. A recess having a bottom surface and a side surface is formed in the molded body 40, and the light emitting element 10 is placed on the bottom surface of the recess. The light emitting element 10 has a pair of positive and negative electrodes, and the pair of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30 via the wire 60. The light emitting element 10 is sealed with a sealing member 50. The sealing member 50 is preferably made of a thermosetting resin such as an epoxy resin, a silicone resin, an epoxy-modified silicone resin, or a modified silicone resin. The sealing member 50 includes a first phosphor 71 that emits red light that converts the wavelength of light from the light emitting element 10, a second phosphor 72 that emits green light, and a sealing resin.

  The sealing member 50 is formed by being filled with a translucent resin or glass so as to cover the light emitting element 10 placed in the recess of the light emitting device 100. In view of ease of production, the material of the sealing member is preferably a translucent resin. As the translucent resin, a silicone resin composition is preferably used, but an insulating resin composition such as an epoxy resin composition or an acrylic resin composition can also be used. The sealing member 50 contains the first phosphor 71 and the second phosphor 72, but other materials can be added as appropriate. For example, by including a light diffusing material, the directivity from the light emitting element can be relaxed and the viewing angle can be increased.

  The sealing member 50 functions not only as a member for protecting the light emitting element 10, the first phosphor 71 and the second phosphor 72 from the external environment, but also as a wavelength conversion member. In FIG. 1, the first phosphor 71 and the second phosphor 72 are partially unevenly distributed in the sealing member 50. Thus, by arranging the first phosphor 71 and the second phosphor 72 close to the light emitting element 10, the wavelength of light from the light emitting element 10 can be efficiently converted, and the light emission efficiency is excellent. It can be a light emitting device. In addition, arrangement | positioning with the sealing member 50 containing the 1st fluorescent substance 71 and the 2nd fluorescent substance 72, and the light emitting element 10 is not limited to the form which arrange | positions them closely, 1st fluorescence Considering the influence of heat on the body 71 and the second phosphor 72, the light emitting element 10 and the first phosphor 71 and the second phosphor 72 are spaced apart in the sealing member 50. You can also Further, by mixing the first phosphor 71 and the second phosphor 72 with the entire sealing member 50 at a substantially uniform ratio, it is possible to obtain light in which color unevenness is further suppressed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Production example of fluoride phosphor>
(Comparative Example 1)
209.9 g of K ₂ MnF ₆ was weighed and dissolved in 3.3 L of 55% by mass HF aqueous solution to prepare a first solution. Further, 2343 g of KHF ₂ was weighed and dissolved in 9.9 L of 55% by mass HF aqueous solution to prepare a second solution. Subsequently, 4.28 L of an aqueous solution containing 40% by mass of H ₂ SiF ₆ was prepared as a third solution.
Next, the first solution and the third solution were added dropwise over about 50 minutes while stirring the second solution at room temperature. The obtained precipitate was subjected to solid-liquid separation, washed with ethanol, and dried at 90 ° C. for 10 hours to produce the fluoride phosphor of Comparative Example 1.

Example 1
239.9 g of K ₂ MnF ₆ was weighed and dissolved in 3.3 L of 55% by mass HF aqueous solution to prepare a first solution. Further, 2343 g of KHF ₂ was weighed and dissolved in 9.9 L of 55% by mass HF aqueous solution to prepare a second solution. Subsequently, 4.28 L of an aqueous solution containing 40% by mass of H ₂ SiF ₆ was prepared as a third solution.
Next, while stirring the second solution at room temperature, the first solution and the third solution were added dropwise over about 20 hours. The obtained precipitate was solid-liquid separated, washed with ethanol, and dried at 90 ° C. for 10 hours to produce the fluoride phosphor of Example 1.

(Example 2)
A liquid medium 1 was prepared by dissolving 7.0 g of KHF ₂ in 33 g of 55% by mass HF aqueous solution. The autoclave coated with fluororesin was charged with 50 g of the liquid medium 1 and the fluoride phosphor obtained in Example 1, and subjected to heat and pressure treatment at 170 ° C. and about 2.3 MPa for 12 hours. After the solid-liquid separation, washing with ethanol was performed, followed by drying at 90 ° C. for 10 hours to produce the fluoride phosphor of Example 2.

(Example 3)
A fluoride phosphor of Example 3 was produced in the same manner as in Example 1 except that the amount of the HF aqueous solution in the second solution was changed to 10.5 L.

Example 4
The fluoride phosphor obtained in Example 3 was treated under the same conditions as in Example 2 to produce the fluoride phosphor of Example 4.

(Example 5)
A fluoride phosphor of Example 5 was produced in the same manner as in Example 1 except that K ₂ MnF ₆ of the first solution was changed to 359.9 g.

<Evaluation>
(Light emission luminance characteristics)
With respect to each of the obtained fluoride phosphors, normal emission luminance characteristics were measured. The light emission luminance characteristics were measured under conditions of an excitation wavelength of 460 nm. The measurement was carried out at 25 ° C. using a fluorescence spectrophotometer F-4500 (manufactured by Hitachi High-Tech). The results are shown in Table 1 as relative luminance with the comparative example being 100%. In addition, the chromaticity coordinates of fluorescence are also shown.

(Mn amount)
About each obtained fluoride fluorescent substance, the composition analysis by ICP was performed and the amount of Mn was computed as an analysis Mn density | concentration (composition ratio when K is a reference | standard, it corresponds to a of Formula (I)). The results are shown in Table 1.

(Infrared spectroscopy: FT-IR evaluation)
About each obtained fluoride fluorescent substance, it was set as KBr background using the Fourier-transform type | mold infrared spectrometer iS50 (made by Thermo Fisher Scientific), and the infrared absorption spectrum was measured by the diffuse reflection method. Correction was performed using the value at 4000 cm ⁻¹ as a baseline, and the absorption spectrum was calculated using the Kubelka-Munk transformation, normalized with the maximum peak.

FIG. 2 is a diagram showing an infrared absorption spectrum of the fluoride phosphor according to each example and an infrared absorption spectrum of the fluoride phosphor according to the comparative example. 3, of the infrared absorption spectrum shown in FIG. 2 is an enlarged view showing wave number enlarged portion of 3900Cm ^-1 from 3000 cm ^-1. 1050 cm ^-1 or 1350 cm ^-1 was noted peak component follows and 3500 cm ^-1 or 3800 cm ^-1 The following wavenumber range was determined integrated area of the peak (IR peak area), respectively. Further IR peak area ratio Z ¹ was determined as an area ratio represented by (P) equation. The peak area of 3500 cm ^-1 or ^{3800 cm} -1 ^{cm -1} obtains the area as a background a straight line connecting the intensity in the intensity and 3800 cm ^-1 in 3000 cm ^-1, the peak area of 1050 cm ^-1 or 1350 cm ^-1 or less Obtained the area with a straight line connecting the intensity at 1050 cm ^{−1 and} the intensity at 1350 cm ⁻¹ as the background. Here, 1050 cm ^-1 or 1350 cm ^-1 or less is derived from fluoride phosphors, 3000 cm ^-1 or 3800 cm ^-1 or less _{H 2} O derived, 3500 cm ^-1 or 3800 cm ^-1 or less is considered to be derived from Si-OH.
Z ¹ = (3500cm ^-1 or 3800 cm ^-1 The following peak areas) / (1050 cm ^-1 or 1350 cm ^-1 The following peak areas) (P)

<Example of manufacturing a light emitting device>
The fluoride phosphor of Example 1 was used as the first phosphor. As the second phosphor, β sialon having an emission peak wavelength in the vicinity of 540 nm represented by Si, Al) ₆ (O, N) ₈ : Eu was used. The binder was a resin, and a silicone resin was used, and the color tone of the light emitting device was adjusted so that the chromaticity coordinates x / y = 0.280 / 0.280. After preparing a package having a side wall that forms a recess and arranging a light emitting element in the recess, a sealing material mixed with phosphor and resin is injected into the recess of the package using a syringe, and the silicone resin is cured to emit light. A device was made. As the light emitting element, a semiconductor light emitting element having a dominant wavelength of 451 nm was used.

(Durability of light emitting device: LED durability)
About the light emitting device using the fluoride phosphors of Examples 1 and 2 and Comparative Example 1 obtained above, the chromaticity after about 150 hours had been continuously emitted at a current value of 150 mA in an environment of 85 ° C. The x value in coordinates was measured. The amount of change in the x value from the initial value of each light emitting device is assumed to be Δx, and the shift value of Δx of Comparative Example 1 is used as a reference, and the value obtained by dividing Δx of each Example by Δx of Comparative Example 1 is the Δx change rate. The relative color shift rate was compared and evaluated. The Δx rate of change was set to 100 based on Comparative Example 1, and a smaller value represents a decrease in color shift after the same elapsed time, indicating that the durability is good. means.

As shown in Table 1, the Mn amounts of the phosphors of Comparative Example 1 and Examples 1 to 5 are 0.034 to 0.062 as the range of a in the formula (I), and the chromaticity coordinates of the phosphor itself Are substantially the same. IR peak area ratio ^{Z 1} obtained by infrared spectroscopy measurements Example 1-4 ^{0.2 × 10 -3 ~2.0 × 10 -3} , and Comparative Example 1 of 3.3 × ^{10 -3} You can see that it is smaller. It can be seen that heat-treated Example 2 and Example 4 have higher relative luminance and LED durability as compared with Examples 1 and 3 which are not heat-treated, respectively. The main difference between Examples 1 and 3 and Examples 2 and 4 is the average particle size, and the larger the average particle size, the higher the relative luminance of the fluoride phosphor, and the higher LED durability. Is also maintained.

In Example 5 having the largest amount of Mn among the examples, the IR peak area ratio Z ¹ is smaller than that of the comparative example. That is, the LED durability is also improved in Example 5 having a large amount of Mn, in which defects tend to occur relatively easily in the fluoride fluorescent material.

Thus, when the specific IR peak component in the fluoride phosphor is reduced, mainly the Si-OH-derived component is reduced, OH, H ₂ O, etc. bonded to the fluoride are reduced, and fluoride fluorescence It is considered that the defects in the body are reduced, and thus the LED durability is improved.

  The light emitting device of this embodiment includes various light sources such as an illumination light source, a liquid crystal backlight light source, various indicator light sources, an in-vehicle light source, a display light source, a sensor light source, a traffic light, an in-vehicle component, and a signboard channel letter. Can be used for

  10: light emitting element, 50: sealing member, 71: first phosphor, 72: second phosphor, 100: light emitting device

Claims (6)

Including particles having a composition represented by the following formula (I):
Fluoride phosphor IR peak area ratio ^{Z 1} to the infrared absorption spectrum given by the following formula (P) is less than 2.5 × ^{10 -3.}
A ₂ [M _1-a Mn ⁴⁺ _a F ₆ ] (I)
(In the formula, A represents at least one cation selected from the group consisting of K ⁺ , Li ⁺ , Na ⁺ , Rb ⁺ , Cs ⁺ and NH ₄ ⁺ , and M represents a Group 4 element and a Group 4 element. This represents at least one element selected from the group consisting of Group 14 elements, and a satisfies 0.01 <a <0.20.)
Z ¹ = (3500cm ^-1 or 3800 cm ^-1 The following peak areas) / (1050 cm ^-1 or 1350 cm ^-1 The following peak areas) (P) 2. The fluoride phosphor according to claim 1, wherein the IR peak area ratio Z ¹ is 1.0 × 10 ⁻³ or less. 3. The fluoride phosphor according to claim 1, wherein the IR peak area ratio Z ¹ is 1.0 × 10 ⁻⁵ or more. The fluoride fluorescent substance according to any one of claims 1 to 3, wherein A in the general formula (I) contains K ⁺ and M contains Si. An excitation light source that emits light in a wavelength range of 380 nm to 485 nm;
A first phosphor containing the fluoride phosphor according to any one of claims 1 to 4,
A second phosphor that absorbs light in a wavelength range of 380 nm to 485 nm and has a maximum emission wavelength in a wavelength range of 495 nm to 590 nm;
A light emitting device comprising: The second phosphor is a β sialon phosphor having a composition represented by the following formula (IIa), a halosilicate phosphor having a composition represented by the following formula (IIb), and represented by the following formula (IIc). Selected from the group consisting of a silicate phosphor having a composition represented by the following formula, a rare earth aluminate phosphor having a composition represented by the following formula (IId), and a sulfide phosphor having a composition represented by the following formula (IIe): The light emitting device according to claim 5, wherein the light emitting device is at least one kind.
Si _6-t Al _t O _t N _8-t : Eu (IIa)
(In the formula, t satisfies 0 <t <4.2.)
(Ca, Sr, Ba) ₈ MgSi ₄ O ₁₆ (F, Cl, Br) ₂ : Eu (IIb)
(Ba, Sr, Ca, Mg) ₂ SiO ₄ : Eu (IIc)
(Y, Lu, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce (IId)
(Ba, Sr, Ca) Ga ₂ S ₄ : Eu (IIe)