Fluorescent materials and their manufacturing methods

Abstract

A phosphor, which is coated with alumina, and whose spectrum is separated in 1H-NMR spectra within the range of 1H chemical shift values ​​of 0.5 ppm to 11 ppm, wherein when the peak with a 1H chemical shift value of 4.0 ppm to 5.5 ppm is designated as peak 1, the peak with a 1H chemical shift value of 2.0 ppm to 2.8 ppm is designated as peak 2, and the peak with a 1H chemical shift value of 0.5 ppm to 1.5 ppm is designated as peak 3, the integral value S2 of peak 2 within the range of -2 ppm to 12 ppm, relative to the sum of the integral values ​​S1 of peak 1, S2 of peak 2, and S3 of peak 3 within the above range, is S2 / (S1 + S2 + S3) ≤ 0.39.

Description

[Technical Field]

[0001] This invention relates to a phosphor and its manufacturing method. [Previous Technology]

[0002] The industry has developed various light-emitting devices with a wide range of color reproduction. These devices, for example, use blue light-emitting diodes (LEDs) as the light source and combine them with phosphors that emit green or red fluorescence. For these phosphors, high moisture resistance is required; that is, the luminous intensity should not decrease even when exposed to high humidity. One method to improve the moisture resistance of phosphors is, for example, coating the surface of the phosphor with an inorganic material using atomic layer deposition (ALD). For example, the technique described in Patent Document 1 can be cited as an example of this technology.

[0003] Patent Document 1 discloses a fluorescent particle coated with an inorganic material using an ALD (Alternating Current Deposition). According to the technology described in that document, in order to improve the moisture resistance of the fluorescent particle, an inorganic material is thinly coated onto the phosphor using an ALD in approximately several dozen cycles. Previous Art Documents Patent Documents

[0004] Patent Document 1: US2012 / 199793A1 [Summary of the Invention]

[0005] The technology described in Patent Document 1 sets the number of cycles of coating using ALD to the above-mentioned level in order to prevent the reduction of luminous intensity and ensure moisture resistance, but it still cannot be said to ensure sufficient moisture resistance.

[0006] Therefore, the object of the present invention is to provide a phosphor that has excellent moisture resistance even when coated thinly, and a method for manufacturing the same.

[0007] The present invention provides a phosphor coated with alumina, and in a 1H-NMR (hydrogen-nuclear magnetic resonance) spectrum, peak separation is performed in the range of 1H chemical shift values ​​from 0.5 ppm to 11 ppm. When the peak with a 1H chemical shift value of 4.0 ppm to 5.5 ppm is designated as peak 1, the peak with a 1H chemical shift value of 2.0 ppm to 2.8 ppm is designated as peak 2, and the peak with a 1H chemical shift value of 0.5 ppm to 1.5 ppm is designated as peak 3, the integral value S2 of peak 2 in the range of -2 ppm to 12 ppm, relative to the total integral value S1 of peak 1, S2 of peak 2, and S3 of peak 3 in the above range, is S2 / (S1 + S2 + S3) and is 0.39 or less.

[0008] Furthermore, the present invention provides a phosphor coated with alumina, and the electron diffraction pattern is measured by using nano-beam electron diffraction with a transmission electron microscope. The diffraction intensity is averaged radially from the center of the transmission point to obtain the average diffraction intensity relative to the magnitude Q of the scattering vector. A one-dimensional curve is obtained by plotting the average diffraction intensity. In the one-dimensional curve, the ratio S4 of the integral value of the peak in the range of Q from 17 nm to 26 nm to BG4 of the background signal in the same range is 0.09 or higher.

[0009] Furthermore, the present invention provides a method for manufacturing a phosphor coated with alumina, which involves coating the phosphor substrate with alumina by atomic layer deposition and then subjecting it to heat treatment at a temperature between 200°C and 800°C.

Implementation Method

[0011] Hereinafter, the present invention will be described based on a preferred embodiment. The fluorescent system of the present invention is coated with alumina. Alumina has excellent water vapor barrier properties, therefore, by coating it onto a phosphor, its moisture resistance becomes excellent. From the viewpoint of improving corrosion resistance, it is particularly useful to coat a phosphor having a specific surface area as described below with alumina. In this specification, when referring to "phosphor," according to the context, it means the phosphor before alumina coating and the phosphor after alumina coating.

[0012] In this specification, "alumina" refers to aluminum compounds represented by the formula Al₂O₃, and aluminum oxides having at least a side oxygen ligand (O₂⁻) as a ligand. Even aluminum compounds having ligands other than the side oxygen ligand, such as hydroxyl ligands (OH⁻) or alkyl ligands, are also included in alumina if they have a side oxygen ligand.

[0013] There are no particular limitations on the phosphors that can be used in this invention, and various previously known phosphors can be used. Examples include sulfide phosphors, silicate halide phosphors, nitride phosphors, oxide phosphors, etc., which can be used alone or in combination of several types.

[0014] Examples of the above-mentioned sulfide-based fluoresces include: MGa₂S₄ (where M is a monovalent or divalent metal element), CaS, ZnS, (ZnCd)S, (CaSr)S, La₂O₂S, Y₂O₂S, Gd₂O₂S, and SrS. Furthermore, examples of luminescent centers in the above-mentioned sulfide-based fluoresces include: europium (Eu), cerium (Ce), manganese (Mn), and samarium (Sm).

[0015] As an example of the above-mentioned silicate halide phosphors, MSiX6:Mn (M is selected from one or more of Li, Na, and K, and X is selected from one or more of F, Cl, Br, and I; a portion of Si can be replaced by Ge; Mn is the luminescent center) etc.

[0016] Examples of the above-mentioned nitride-based phosphors include: M 2Si 5N 8:Eu, MAlSiN 3:Eu, MSi 7N 10:Eu, M 1.8Si 5O 0.2N 8:Eu, M 0.9Si 7O 0.1N 10:Eu, MSi 2O 2N 2:Eu (M is selected from one or more of Sr, Ca, Ba, Mg, and Zn), etc.

[0017] Examples of the above-mentioned oxide-based phosphors include: M12-xM2xO3 (M1 and M2 are each independently selected from one or more of Sc, Y, La, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and x is 0 or more and 2 or less), ZnO, ZnGa2O4, etc.

[0018] In this invention, it is preferable to use a sulfide-based phosphor as the phosphor because its emission spectrum has a half-width at half-maximum and peak wavelength suitable for achieving a light-emitting device with higher luminous intensity and higher color reproducibility. More preferably, MGa₂S₄ (M is a monovalent or divalent metal element) is used, and Eu is used as the luminescent center; further preferably, SrGa₂S₄:Eu is used as the sulfide-based phosphor.

[0019] One embodiment of the present invention is characterized by the presence of a 1H-NMR spectrum of a phosphor. Specifically, in the 1H-NMR spectrum of a phosphor, peak separation is performed within the range of 0.5 ppm to 11 ppm 1H chemical shift value, and the peak with a 1H chemical shift value of 4.0 ppm to 5.5 ppm at its peak is designated as peak 1, the peak with a 1H chemical shift value of 2.0 ppm to 2.8 ppm at its peak is designated as peak 2, and the peak with a 1H chemical shift value of 0.5 ppm to 1.5 ppm at its peak is designated as peak 3. Furthermore, the integral value S2 of peak 2 within the range of 1H chemical shift values ​​from -2 ppm to 12 ppm, relative to the sum of the integral values ​​S1 of peak 1, S2 of peak 2, and S3 of peak 3 within the same range, is S2 / (S1 + S2 + S3) or less. In this specification, "the point where the 1H chemical shift value is closest to X (ppm)" refers to the spectral point whose 1H chemical shift value is closest to X (ppm) among all the spectral points constituting the 1H-NMR spectrum. Also, for ease of explanation, the aforementioned 1H chemical shift value "from the point closest to -2 ppm to the point closest to 12 ppm" is also referred to as "between -2 ppm and 12 ppm".

[0020] Furthermore, there are cases where, for example, multiple peaks with apexes are observed within the range of peak 1, i.e., 4.0 ppm to 5.5 ppm. In this case, in this specification, the sum of all peaks with apexes within this range is referred to as peak 1. The same applies to peaks 2 and 3; when multiple peaks with apexes within the specified range are observed, the sum of all of them is referred to as peak 1, peak 2, or peak 3, respectively. Moreover, the ranges of the aforementioned chemical shift values ​​are obtained as follows: using a nuclear magnetic resonance apparatus with a resonance frequency of 600 MHz for the 1H nucleus, at room temperature (21°C to 25°C), the peak of the 1H spectrum obtained by measuring adamantane powder sample using the MAS (magic angle spinning) method with a sample rotation speed of 60 kHz (1.91 ppm) is used as an external standard and corrected to obtain the aforementioned ranges of chemical shift values. The 1H-NMR spectrum of fluorescent materials can be complex, consisting of multiple overlapping peaks. Therefore, peak separation is necessary within a chemical shift range of 0.5 ppm to 11 ppm. This peak separation allows for the accurate calculation of integral values ​​S1 to S3.

[0021] The 1H MAS NMR spectrum (also referred to as "1H-NMR spectrum" in this invention) can be measured, for example, under the following conditions: Magnetic field: 14.1 T (1H 600 MHz) Spectrometer: AVANCE NEO600 manufactured by Bruker Measurement and data processing software: TopSpin manufactured by Bruker NMR probe: 1.3 mm MAS probe Sample rotation speed: 60 kHz Standard sample for chemical shift value and radio frequency intensity: Adamantane Chemical shift value reference: The central peak of adamantane measured by MAS method at a sample rotation speed of 8 kHz is set to 1.91 ppm. Spectral center (O1 value - SR value (chemical shift notation)): 4.7 ppm Radio frequency pulse intensity: Set to a pulse width of 2.5 μs, where the pulse width is the pulse width that maximizes the peak value of adamantane when the spectral center is 1.91 ppm. RF pulse width: 2.5 μs; Measurement interval: 2.0 μs (DW = 1.0 μs on the above software); Number of measurement points: 10,000 (TD = 20,000 on the above software); Number of spectral points (SI on the above software): 65,536.

[0022] In the calculation software, the spectrum obtained under the above measurement conditions is corrected for a baseline, and then the background spectrum is subtracted to obtain the 1H MAS NMR spectrum. The baseline is created by connecting the points obtained by arithmetically averaging the chemical shift values ​​and signal intensities of all points from the point closest to 11.5 ppm to the point closest to 12 ppm, and the points obtained by arithmetically averaging the chemical shift values ​​and signal intensities of all points from the point closest to -0.25 ppm to the point closest to 0.25 ppm. In this specification, the spectrum obtained by the above method is referred to as the "H measured spectrum". Peaks 1 to 3 above are obtained by peak separation of the H measured spectrum. Peak separation can be implemented as follows: For the measured H spectrum, the calculated spectrum, which is produced by the sum of the pseudo-Voigt functions of the number of peaks, is fitted within the range of 0 ppm to 6.5 ppm for the 1H chemical shift value. The pseudo-Voigt function is the sum of the Lorentz function and the Gaussian function of the same half-peak full amplitude. The pseudo-Voigt function f(x) used in peak separation is shown in the following equation (1). The peak integral value of each peak is obtained by summing the signal intensities of the peaks calculated by the pseudo-Voigt function for points in the range of -2 ppm to 12 ppm of the measured H spectrum. Furthermore, the "pseudo-Voigt function" is based on "6. Distribution function and pattern decomposition method" in "Special Issue: New Advances in Powder Diffraction Method" of the Journal of the Japanese Society for Crystallography 34, 86 (1992).

[0023] The background spectrum used to obtain the above-mentioned spectrum is calculated as follows. A fluorescent powder sample without alumina coating is used as a blank sample, and the blank sample is measured by 1H-MAS NMR under the above-mentioned measurement conditions. The measurement results of the blank sample under the above conditions are corrected for a baseline, and the resulting spectrum is used as the spectrum of the blank sample. Peak separation using a pseudo-Woythe function is performed on the spectrum of the blank sample in the same manner as above. Then, among the separated peaks, peaks with a higher probability of representing water or hydrated water, i.e., peaks with a chemical shift value of 4.5 ppm to 5.0 ppm, are all deleted. All other peaks are summed, and the sum spectrum is used as the background spectrum. Furthermore, to reduce the error caused by subtraction, the spectrum of the blank sample, which is the source of the background spectrum, is used, and the spectrum of the sample measured on the same day or at a time as close as possible to the time when the background spectrum is subtracted. Furthermore, in order to obtain the background spectrum of the alumina-coated phosphor, it is only necessary to treat the phosphor with an alkali such as sodium hydroxide solution to remove the alumina, then wash and dry it to remove the alumina and alkali residues, and then perform the above-mentioned measurements on the resulting phosphor.

[0024] [Number 1]

[0025] In Equation (1), x represents the horizontal axis value (chemical shift value) of the 1H MAS NMR spectrum, x0 represents the chemical shift value of the peak, S represents the calibration coefficient used to make the vertical axis value of the peak consistent with the measured value, η represents the peak area ratio of the Lorentz function (the first term) in the range of -∞ (negative infinity) to +∞ (positive infinity), Δ represents the half-peak amplitude of the peak, π represents pi, ln represents the natural logarithm function, and exp represents the natural exponential function. In peak separation, the pseudo-Voyt functions of each peak, x0, Δ, η, and S, are used as variables. The root mean square deviation between the measured and calculated chemical shift values ​​in the range of 0 ppm to 6.5 ppm is minimized, and the solver function of the calculation software is used for fitting.

[0026] Most alumina-coated phosphors have a partial Al-OH structure on their surface. Peak 1 mentioned above is a peak from this partial Al-OH structure. On the other hand, if the alumina-coated phosphor is heat-treated at a specific temperature, as in the manufacturing method described below, the partial Al-OH structure dehydrates, and an Al-O-Al cross-linked structure is formed on the phosphor surface instead. By increasing the presence of the Al-O-Al cross-linked structure on the phosphor surface, the alumina coating layer on the phosphor surface becomes less porous and more robust, thereby improving the moisture resistance of the phosphor.

[0027] That is, in order to obtain a phosphor with high moisture resistance, it is preferable to reduce the presence ratio of the Al-OH partial structure and increase the presence ratio of the Al-O-Al cross-linked structure. As mentioned above, peak 2 is a peak from the Al-OH partial structure. Therefore, by making the ratio of the integral value S2 of peak 2 to the sum of the integral values ​​S1 of peak 1, S2 of peak 2, and S3 of peak 3, S2 / (S1+S2+S3), less than 0.39, the presence ratio of Al-O-Al as described above is increased. This indicates that the phosphor has excellent moisture resistance. Furthermore, peak 3 also depends on the phosphor preparation method, for example, it is a peak from the Al-CH2 or Al-CH3 partial structure. From this perspective, S2 / (S1+S2+S3) is preferably 0.35 or less, more preferably 0.2 or less, and even more preferably 0.1 or less, with a lower limit of 0.

[0028] In another embodiment of the present invention, the electron diffraction pattern of the phosphor of the present invention is determined by nanobeam electron diffraction using a transmission electron microscope. The diffraction intensity is averaged radially from the center of the transmission point to obtain the average diffraction intensity relative to the magnitude Q of the scattering vector. A one-dimensional curve is obtained by plotting the average diffraction intensity. In the one-dimensional curve, the ratio S4 / BG4 of the integral value of the peak in the range of 17 nm - 1 to 26 nm - 1 for Q is preferably 0.09 or higher. In the phosphor of the present invention, the alumina coating the phosphor is preferably amorphous. In other words, the alumina coating the phosphor of the present invention preferably has a chemical structure that is less ordered than a crystalline structure. However, an S4 / BG4 ratio of 0.09 or higher indicates an increase in the order of interatomic distances in the range of 1 nm or less in the alumina. The reason for the increased orderliness of interatomic distances below 1 nm is that, for example, when a phosphor is manufactured according to the manufacturing method described below, some Al-OH structures on the phosphor surface decrease due to dehydration, and the proportion of Al-O-Al cross-linked structures increases. Therefore, the proportion of interatomic distances from the Al-O-Al cross-linked structures increases. When such cross-linked structures are more abundant on the phosphor surface, the alumina coating on the phosphor surface becomes less porous and more robust, thus improving the phosphor's moisture resistance. There is no particular upper limit to S4 / BG4; generally, the upper limit is around 100.

[0029] Regarding the background signal mentioned above, for the one-dimensional curve diagram mentioned above, draw the common tangent line before and after the shoulder peak of the curve generated in the intensity distribution, and regard it as the background function to obtain the background signal mentioned above.

[0030] The specific surface area of ​​the phosphor of the present invention in the alumina-coated state is preferably 1 m² / g or more and 10 m² / g or less, more preferably 1 m² / g or more and 5 m² / g or less, and even more preferably 1 m² / g or more and 3 m² / g or less. By making the specific surface area 1 m² / g or more, it is suitable for use in applications such as micro LEDs or small LEDs where small particle size is required. Furthermore, by making the specific surface area 10 m² / g or less, coating can be performed while suppressing necking between phosphor particles. Furthermore, the specific surface area can be determined as follows: using a nitrogen-helium mixture containing 30% by volume nitrogen as the adsorbent gas and 70% by volume helium as the carrier gas, and a specific surface area measuring device (e.g., Mounttech Corporation, HM model-1210), the determination is performed according to JIS R 1626 "Determination of Specific Surface Area of ​​Precision Ceramic Powders Based on Gas Adsorption BET (Brunauer-emmett-teller) Method" "6.2 Flow Method" "(3.5) Single Point Method".

[0031] When the phosphor of the present invention is any of the above embodiments, the aluminum content of the phosphor is preferably 10,000 ppm or more and 100,000 ppm or less, more preferably 15,000 ppm or more and 80,000 ppm or less, and even more preferably 20,000 ppm or more and 60,000 ppm or less. By setting the aluminum content to 10,000 ppm or more, the moisture resistance of the phosphor can be sufficiently improved.

[0032] The aluminum content mentioned above was determined by ICP (inductively coupled plasma) emission spectroscopy analysis.

[0033] Next, the method for manufacturing the phosphor of the present invention will be described. The phosphor of the present invention can be obtained, for example, by coating the phosphor with alumina using an alumina solvent (ALD) followed by heat treatment. The ALD used in the present invention provides a good stepped coating, thus allowing for excellent moisture resistance even with a thin coating that does not inhibit the phosphor's performance. When manufacturing the phosphor of the present invention using this method, the ALD step can be performed, for example, as follows: (a) Containing the phosphor substrate in a reaction vessel. (b) Introducing trimethylaluminum vapor into the reaction vessel. (c) Removing the trimethylaluminum vapor and reaction byproducts by rinsing. (d) Introducing water vapor into the reaction vessel. (e) Removing the water vapor and reaction byproducts by rinsing. (f) Repeating steps (b) to (e).

[0034] The types of phosphor substrates used in step (a) are as described above. In step (b), trimethylaluminum is used as a precursor for coating with alumina; aluminum ethoxide or aluminum isopropoxide may also be used.

[0035] In this invention, nitrogen, argon, etc. can be used as rinsing in steps (c) and (e).

[0036] In this invention, in step (d), water vapor is used to oxidize the precursor. Ozone may be used instead of water vapor, or ozone may be used in addition to water vapor.

[0037] In this invention, the number of repetitions in step (f) is preferably set to 10 to 150 cycles, more preferably 20 to 120 cycles, and even more preferably 25 to 80 cycles. By setting the number of repetitions to 10 cycles or more, a phosphor with sufficient moisture resistance can be obtained. Furthermore, by setting the number of repetitions to 150 cycles or less, the manufacturing cost of the phosphor of this invention can be reduced, and the manufacturing time can be shortened.

[0038] Next, the heat treatment after coating will be explained. By heat treating the coated phosphor, some of the Al-OH structures present on the surface of the phosphor can be transformed into Al-O-Al cross-linked structures through a dehydration reaction. As mentioned above, the Al-O-Al cross-linked structure improves the moisture resistance of the phosphor, therefore, the heat treatment has the effect of improving the moisture resistance of the phosphor.

[0039] The heat treatment is preferably carried out at a temperature between 200°C and 800°C, more preferably between 300°C and 700°C, and even more preferably between 500°C and 650°C. By carrying it at a temperature above 200°C, the moisture resistance of the phosphor can be sufficiently improved. Furthermore, by carrying it at a temperature below 800°C, the occurrence of heat-induced side reactions can be suppressed, and a phosphor with excellent luminescence intensity or moisture resistance can be obtained. The temperature of the heat treatment can be fixed during the heat treatment step, or it can be varied over time within the above temperature range.

[0040] The heat treatment can be carried out in an inert gas environment such as nitrogen or argon, or in an oxidizing gas environment such as the atmosphere. In terms of preventing oxidation of the phosphor and improving its moisture resistance, it is preferable to carry out the treatment in an inert gas environment. Furthermore, among various inert gases, nitrogen is particularly preferred in terms of cost reduction. The heat treatment can also be carried out under reduced pressure in the above-mentioned environments. Alternatively, the heat treatment can be carried out under a vacuum.

[0041] The phosphor of the present invention can be combined with various LEDs, including micro LEDs or small LEDs, to form a light-emitting device. Furthermore, the phosphor of the present invention has excellent moisture resistance, making it suitable for use in high humidity environments.

[0042] Regarding the above embodiments, the present invention further proposes the following phosphor and its manufacturing method. [1] A phosphor is coated with alumina, and in the 1H-NMR spectrum, the spectrum is separated in the range of 0.5 ppm to 11 ppm 1H chemical shift value. When the peak with 1H chemical shift value of 4.0 ppm to 5.5 ppm is designated as peak 1, the peak with 1H chemical shift value of 2.0 ppm to 2.8 ppm is designated as peak 2, and the peak with 1H chemical shift value of 0.5 ppm to 1.5 ppm is designated as peak 3, the integral value S2 of peak 2 in the range of -2 ppm to 12 ppm 1H chemical shift value is S2 / (S1 + S2 + S3) relative to the total value of integral value S1 of peak 1, integral value S2 of peak 2 and integral value S3 of peak 3 in the above range is 0.39 or less. [2] A phosphor is coated with alumina, and the electron diffraction pattern is determined by nano-beam electron diffraction using a transmission electron microscope. The diffraction intensity is averaged radially from the center of the transmission point to obtain the average diffraction intensity relative to the magnitude Q of the scattering vector. A one-dimensional curve is obtained by plotting the average diffraction intensity. In the one-dimensional curve, the ratio of the integral value S4 of the peak in the range of Q being 17 nm -1 to 26 nm -1 to the integral value BG4 of the background signal in the same range, S4 / BG4, is 0.09 or more. [3] The phosphor as described in [1] or [2], wherein the alumina is amorphous. [4] The phosphor as described in any one of [1] to [3], wherein the specific surface area of ​​the phosphor is 1 m2 / g or more and 10 m2 / g or less. [5] The phosphor described in any one of [1] to [4], wherein the aluminum content in the phosphor, as determined by ICP emission spectroscopy analysis, is 10,000 ppm to 100,000 ppm or less. [6] A method for manufacturing an alumina-coated phosphor, wherein a phosphor substrate is coated with alumina by atomic layer deposition and then subjected to heat treatment at 200°C to 800°C. [Example]

[0043] Hereinafter, the present invention will be described in further detail by way of embodiments. However, the scope of the present invention is not limited to these embodiments.

[0044] [Examples 1-4, Comparative Examples 1-3] (Preparation of Fluorescent Materials) SrGa₂S₄:Eu, a sulfide-based fluorescent material, was contained in an ALD reaction vessel and heated to 120°C. Then, trimethylaluminum vapor and water vapor, serving as reactants, were alternately introduced while being rinsed with nitrogen. The introduction of the two reactants was considered as one cycle, and the introduction of the two reactants was repeated in the number of cycles shown in Tables 1-3. Subsequently, the coated fluorescent material was subjected to heat treatment to obtain the fluorescent samples of the examples. This heat treatment was performed under a nitrogen atmosphere at the temperatures shown in Tables 1-3. In contrast, no heat treatment was performed in Comparative Examples 1-3.

[0045] (Determination of aluminum content) The aluminum content in each sample of the examples and comparative examples was determined using an ICP emission spectrometer (manufactured by Hitachi High-Tech Science: PS3520UVDDII).

[0046] (Evaluation of Moisture Resistance) Each sample from the Examples and Comparative Examples was mixed with silicone resin (manufactured by Toray Dow Corning: OE-6630) at a ratio of 40 wt%, coated onto a glass plate to a thickness of approximately 300 μm, and heat-cured at 140°C for 1 hour to obtain test pieces. These test pieces were used to evaluate moisture resistance. Specifically, the external quantum efficiency of the test pieces was measured before and after the HAST (High Accelerated Stress Test). The external quantum efficiency after HAST was divided by the external quantum efficiency before HAST to calculate the retention rate (%) of the external quantum efficiency. Moisture resistance was evaluated based on this retention rate (%). The HAST test was conducted as follows: according to IEC 68-2-66, the sample was stored in a saturated PCT container (120°C, 100% RH) for approximately 24 hours. In Examples 3 and 4, and Comparative Example 3, where the luminescence maintenance rate reached over 94% after 24 hours, the luminescence maintenance rate was also measured after 48 hours of HAST implementation. The external quantum efficiency was measured using a spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd.: FP-8500).

[0047] (1H-NMR Analysis) For each sample of the Examples and Comparative Examples, the 1H-NMR spectra were measured according to the method described above. Peak separation was performed on the obtained NMR spectra within the range of 0.5 ppm to 11 ppm for the 1H chemical shift value. The 1H-NMR spectrum after peak separation of Example 3 is shown in Figure 1.

[0048] Based on the NMR spectrum after peak separation, integral values ​​S1, S2, and S3 were obtained, and S2 / (S1 + S2 + S3) was calculated. The values ​​of S2 / (S1 + S2 + S3) for each embodiment and each comparative example are shown in Tables 1 to 3.

[0049] (Electron diffraction pattern determination by NBD (Nano Beam Diffraction)) The sample was mixed into a thermosetting resin (Gatan G2), defoamed under vacuum at 50°C, and then hardened under vacuum at 120°C. The sample was then sliced ​​using a Ga ion beam with an accelerating voltage of 30 kV using a Thermo Fisher Scientific Scios2 focused ion beam-scanning electron microscope (TEM). The electron diffraction pattern was then determined using a transmission electron microscope (TEM, JEM-2100F, NEC), and accompanying instruments from Nanomegas (ASTAR and Topspin). The measurement conditions are as follows. The TEM settings were: accelerating voltage 200 kV, NBD mode, aα = 3, beam diameter 1 nm, convergence aperture diameter 10 μm, and camera length 100 cm. Regarding the Topspin settings, set it to line scan mode, line scan spacing of 1 nm, number of pixels of 580 pixels × 580 pixels, exposure time of 1 second, no spin advance, and drift correction.

[0050] For the obtained electron diffraction pattern, the script Interactive Rotational Profile of the TEM analysis software Gatan Digital Micrograph was used to calculate the average intensity radially centered on the direct spot. This was used to create a one-dimensional curve plotting the average diffraction intensity relative to the magnitude Q of the scattering vector. Furthermore, a common tangent line was plotted across the shoulder of the curve generated in the intensity distribution, and this was treated as a background function to obtain the background signal of the curve. The one-dimensional curve plotting the average diffraction intensity relative to the magnitude Q of the scattering vector in Example 2 and its background signal are shown in Figure 2.

[0051] Based on the one-dimensional curve obtained above, calculate the ratio S4 / BG4 of the integral value of the peak in the range of Q from 17 nm -1 to 26 nm -1 to the integral value of the background signal in the same range. The value of this ratio is shown in Tables 1 to 3.

[0052] (Determination of specific surface area) Samples from the Examples and Comparative Examples were weighed to obtain 0.1 g to 0.2 g of test samples. The specific surface area of ​​the samples was then determined using a "HM model-1210" manufactured by Mounttech Inc. via nitrogen adsorption (BET single-point method). The obtained specific surface areas are shown in Tables 1 to 3.

[0053] [Table 1] Number of times covered (loop) Heat treatment temperature (°C) Al content (ppm) Moisture resistance evaluation 1 H-NMR NBD Specific surface area (m²) 2 / g) Luminescence retention rate (%) after 24 hours Luminescence retention rate (%) after 48 hours S2 / (S1+S2+S3) S4 / BG4 (Q = 17–26 nm) -1 ) Example 1 25 300℃ 18000 54 - 0 0.105 2.11 Example 2 25 500℃ 18000 84 - 0 0.101 2.22 Comparative Example 1 25 none 18000 8 - 0.4 0.074 2.46

[0054] [Table 2] Number of times covered (loop) Heat treatment temperature (°C) Al content (ppm) Moisture resistance evaluation 1 H-NMR NBD Specific surface area (m²) 2 / g) Luminescence retention rate (%) after 24 hours Luminescence retention rate (%) after 48 hours S2 / (S1+S2+S3) S4 / BG4 (Q = 17–26 nm) -1 ) Example 3 40 500℃ 23000 94 93 0.33 0.119 2.11 Comparative Example 2 40 none 23000 35 - 0.52 0.080 2.16

[0055] [Table 3] Number of times covered (loop) Heat treatment temperature (°C) Al content (ppm) Moisture resistance evaluation 1 H-NMR NBD Specific surface area (m 2 / g) Luminescence retention rate (%) after 24 hours Luminescence retention rate (%) after 48 hours S2 / (S1+S2+S3) S4 / BG4 (Q = 17–26 nm) -1 ) Example 4 100 500℃ 57000 98 98 0.05 0.096 2.02 Comparative Example 3 100 none 60000 102 90 0.56 0.085 2.02

[0056] As shown in Tables 1 to 3, the phosphors of each embodiment underwent overheating treatment after coating, while the phosphors of each comparative example, although having the same number of coating cycles, did not undergo overheating treatment. Compared to the phosphors of the comparative examples, the phosphors of each embodiment exhibited superior moisture resistance. That is, it can be seen that the overheated phosphors exhibited excellent moisture resistance even when coated thinly with fewer cycles. The phosphors of Examples 3 and 4, as well as Comparative Example 3, showed higher moisture resistance, with a luminescence retention rate close to 100% after 24 hours of HAST treatment. Therefore, to more accurately evaluate moisture resistance, the luminescence retention rate was also measured after 48 hours of HAST treatment. The results show that the phosphors of Examples 3 and 4, which underwent overheating treatment, exhibited superior moisture resistance than the phosphor of Comparative Example 3. [Industrial Applicability]

[0057] According to the present invention, a phosphor with excellent moisture resistance even when coated thinly is provided, and a method for manufacturing the same. [Simplified Explanation of the Diagram]

[0010] Figure 1 is a 1H-NMR spectrum of the sample collected from the phosphor obtained in Example 3. Figure 2 is the following one-dimensional curve and its background signal. The above one-dimensional curve is obtained by measuring the electron diffraction pattern of the sample collected from the phosphor obtained in Example 2 using nanobeam electron diffraction with a transmission electron microscope. The diffraction intensity is averaged radially from the center of the transmission point to obtain the average diffraction intensity relative to the magnitude Q of the scattering vector. The above one-dimensional curve is obtained by plotting the average diffraction intensity.

Claims

1. A phosphor, comprising a phosphor substrate coated with alumina, wherein in a 1H-NMR spectrum, peak separation is performed within a 1H chemical shift value range of 0.5 ppm to 11 ppm, wherein peaks with 1H chemical shift values ​​of 4.0 ppm to 5.5 ppm at their apex are designated as peak 1, peaks with 1H chemical shift values ​​of 2.0 ppm to 2.8 ppm at their apex are designated as peak 2, and peaks with 1H chemical shift values ​​of 0.5 ppm to 1.5 ppm at their apex are designated as peak 3, and the integral value S2 of peak 2 within a 1H chemical shift value range of -2 ppm to 12 ppm, relative to the sum of the integral values ​​S1 of peak 1, S2 of peak 2, and S3 of peak 3 within the aforementioned range, is S2 / (S1 + S2 + S3) ≤ 0.

39. The aforementioned phosphor matrix contains M1Ga2S4:M2 (M1 is a monovalent or divalent metallic element, and M2 is selected from one or more of Eu, Ce, Mn and Sm).

2. A phosphor, comprising a phosphor substrate coated with alumina, wherein the electron diffraction pattern is determined by nano-beam electron diffraction using a transmission electron microscope, and the diffraction intensity is averaged radially from the center of the transmission point to obtain an average diffraction intensity relative to the magnitude Q of the scattering vector. A one-dimensional curve is obtained by plotting the average diffraction intensity, wherein the ratio S4 / BG4 of the integral value of the peak in the range of 17 nm-1 to 26 nm-1 to the integral value of the background signal in the same range is 0.09 or higher, wherein the phosphor substrate comprises M1Ga2S4:M2 (M1 is a monovalent or divalent metal element, and M2 is selected from one or more of Eu, Ce, Mn and Sm).

3. The phosphor of claim 1 or 2, wherein the aforementioned alumina is amorphous.

4. The phosphor of claim 1 or 2, wherein the specific surface area of ​​the phosphor is more than 1 m2 / g and less than 10 m2 / g.

5. The phosphor of claim 1 or 2, wherein the aluminum content of the phosphor, as determined by ICP emission spectroscopy analysis, is between 10,000 ppm and 100,000 ppm.

6. A method for manufacturing an alumina-coated phosphor, wherein an alumina-coated phosphor substrate is coated by atomic layer deposition and then subjected to heat treatment at a temperature between 500°C and 800°C, wherein the phosphor substrate comprises M1Ga2S4:M2 (M1 is a monovalent or divalent metal element, and M2 is selected from one or more of Eu, Ce, Mn and Sm).

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