A yellow phosphate long afterglow luminescent material and a preparation method thereof

Abstract

The application discloses a kind of yellow phosphate long afterglow luminescent material and preparation method thereof, the chemical formula of the luminescent material is Rb 1.9 Ba 0.1 Sr 1‑x P2O7: x Eu 2+ ;0.0025≤x≤0.005, the stoichiometric ratio of each raw material in chemical formula is weighed, Rb is introduced by carbonate, Sr and Ba are introduced by carbonate, oxide or nitrate, P is introduced by NH4H2PO4 Or (NH4) 2HPO4, Eu is introduced by Eu2O3;Each raw material is mixed and ground sufficiently to obtain raw material powder;In reducing atmosphere and certain temperature, it is cooled to room temperature with furnace, and is ground to obtain yellow phosphate long afterglow luminescent material.The preparation method is simple, pollution-free, without adding cosolvent, low in cost, suitable for large-scale industrial production, and can obtain yellow long afterglow luminescent material with long afterglow time, high intensity and other advantages.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, and relates to a yellow phosphate long afterglow luminescent material and its preparation method. Background Technology

[0002] Long-afterglow luminescence refers to a material that, when excited by a light source (visible light, ultraviolet light, X-rays, etc.), emits light while simultaneously absorbing and storing light energy. After excitation ceases, the stored energy is slowly released as light, with the luminescence duration ranging from a few microseconds to several days. This phenomenon is generally believed to be caused by the slow release of trapped charge carriers (electrons or holes) under thermal excitation. Over the past few decades, long-afterglow luminescent materials have been widely used in safety indication, low-light illumination, live bio-imaging, and energy storage due to their unique optical properties. Like other lighting and display industries, the ultimate goal of the long-afterglow luminescent material industry is to develop multi-color long-afterglow luminescent materials to achieve full-color nighttime illumination. However, due to the different decay rates of various colors of long-afterglow phosphors, long-afterglow luminescence cannot be achieved using only the three primary colors of red, green, and blue. Currently, blue and green long-afterglow phosphors are mature and used in actual production; however, long-wavelength emission (wavelength greater than 570nm) long-afterglow materials still fall short of the requirements, especially long-wavelength emission yellow long-afterglow materials. This is partly due to the rare earth ions Eu that can produce yellow light emission. 2+ A suitable crystal field environment is required. On the other hand, compared with other colors, yellow light has a shorter wavelength range, only within the range of 577nm to 597nm. Therefore, obtaining a yellow long-afterglow luminescent material is very difficult.

[0003] The patent "Orange-yellow long afterglow phosphor and its preparation method" (patent number 200710056035.7) discloses a method using Eu... 2+ SrSiO5:Eu, an orange-yellow long-afterglow luminescent material for activating ions 2+ , Dy 3+, the preparation needs high temperature, on the one hand, waste energy, on the other hand, increase the manufacturing cost of materials. Patent "a long afterglow luminescent material and its preparation method (patent number 201510217356.5)" discloses a kind of yellow long afterglow material, its afterglow duration is only 5 hours, far less than the afterglow time of blue, green long afterglow material, can not meet the actual application demand. In addition, phosphate is a good matrix, rare earth phosphate luminescent material has the characteristics of low synthesis temperature; it exists in the form of monazite, xenotime and other natural minerals in nature, which determines that it has very stable chemical properties; at the same time, phosphate matrix itself has the advantages of low cost, non-toxic, non-pollution, matrix absorption band located at shorter wavelength. Therefore, it has important scientific and practical significance to obtain yellow long afterglow luminescent material with simple preparation, high afterglow brightness and afterglow time more than 9 hours in phosphate system. Patent application "a kind of yellow long afterglow luminescent material and its preparation method (application number 201410192345.1)" discloses a kind of phosphate yellow long afterglow luminescent material, its afterglow time can reach 9h, but its initial afterglow brightness is obviously lower (about 60 mcd / m 2 ), it is difficult to meet the requirements. SUMMARY

[0004] The purpose of the present application is to provide a kind of yellow phosphate long afterglow luminescent material, which has initial afterglow brightness more than 250 mcd / m 2 And afterglow time can continue 9 hours or more.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is: a kind of yellow phosphate long afterglow luminescent material, chemical formula is Rb 1.9 Ba 0.1 Sr 1-x P2O7: x Eu 2+ ;Wherein, 0.0025≤ x ≤0.005.

[0006] The luminescent wavelength of the yellow phosphate long afterglow luminescent material is 450nm-800nm, and the emission peak is located at 577 nm.

[0007] Another technical scheme adopted by the present application is: a kind of preparation method of the above-mentioned yellow phosphate long afterglow luminescent material, carried out according to the following steps:

[0008] 1) according to the stoichiometric ratio of each chemical element in the chemical formula Rb 1.9 Ba 0.1 Sr 1-x P2O7: x Eu 2+ , the following raw materials are taken respectively:

[0009] Rb2CO3;

[0010] Eu2O3;

[0011] BaCO 3、 BaO or Ba(NO3)2;

[0012] SrCO 3、 SrO or Sr(NO3)2;

[0013] NH4H2PO4 or (NH4)2HPO4;

[0014] Mixing the raw materials, grinding and mixing well to obtain the raw material powder;

[0015] 2) The raw material powder is placed in an environment with a temperature of 800-1000℃ and calcined for 4-6h under a reducing atmosphere, and then cooled to room temperature to obtain the calcined product;

[0016] The reducing atmosphere can be two kinds of gas: the first is a mixed gas composed of 5-25% hydrogen (H2) and 95-75% nitrogen (N2) by volume percentage; the second is a mixed gas composed of 5-25% carbon monoxide (CO) and 95-75% nitrogen (N2) by volume percentage.

[0017] 3) Grinding the calcined product to obtain a yellow phosphor long afterglow luminescent material.

[0018] Under the excitation of ultraviolet light, the electrons of the 4f ground state of the long afterglow luminescent material of the present application will transition to the conduction band, some of the electrons will relax to the excited state of Eu 2+ and produce broadband yellow emission, and some of the electrons will be captured by the electron traps through the conduction band. After stopping the ultraviolet irradiation, these captured electrons will return to the 5d excited state of Eu 2+ through the conduction band, thereby producing yellow long afterglow emission.

[0019] The two key performance parameters of the long afterglow luminescent material are the initial brightness of the afterglow and the afterglow time, and the initial brightness of the long afterglow luminescent material of the present application is 261.6 mcd / m 2 , and the afterglow time can reach more than 12h, which is higher than that of some Ba 2+ non-equivalent substitution Rb + In the process of non-equivalent substitution Rb 2+ , rich defects are introduced into the material, so that the material exhibits excellent afterglow performance.

[0020] The preparation method of the present application has the following advantages:

[0021] 1) Eu 2+As activator ions, low-temperature calcination yields a yellow long-afterglow luminescent material that emits a peak at 577 nm after excitation by light with a wavelength of 200–400 nm.

[0022] 2) The preparation method is simple, pollution-free, requires no addition of co-solvents, and has low cost, making it suitable for large-scale industrial production.

[0023] 3) The obtained long-afterglow luminescent material has a long afterglow time and high intensity. Attached Figure Description

[0024] Figure 1 The image shows the XRD pattern of the yellow long-afterglow luminescent material prepared in Example 1.

[0025] Figure 2 The excitation and emission spectra of the yellow long-afterglow luminescent material prepared in Example 1 are shown.

[0026] Figure 3 The afterglow spectra of the yellow long-afterglow luminescent material prepared in Example 1 were measured after irradiation under an ultraviolet lamp for 10 minutes and the light source was turned off, respectively, at 30 s and 900 s.

[0027] Figure 4 The image shows the afterglow decay curve of the yellow long afterglow luminescent material prepared in Example 1. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] Press Rb 1.9 Ba 0.1 Sr 0.9975 P2O7: 0.0025Eu 2+ According to the stoichiometric ratio shown in the molecular formula, 0.50728 g of Rb2CO3, 0.34049 g of SrCO3, 0.04563 g of BaCO3, 0.53191 g of NH4H2PO4 and 0.00102 g of Eu2O3 were weighed out, thoroughly mixed and ground to obtain raw material powder. The raw material powder was transferred to an alumina crucible and placed in a calcining furnace. A reducing atmosphere consisting of 5% hydrogen and 95% nitrogen by volume was introduced, and the mixture was calcined at 850℃ for 4 hours. After cooling to room temperature in the furnace, the calcined material was ground to obtain a yellow phosphate long afterglow luminescent material.

[0031] Figure 1 The image shows the XRD pattern of the yellow long-afterglow luminescent material prepared in Example 1. Figure 1It can be seen that the XRD pattern of the yellow long-afterglow luminescent material prepared in Example 1 matches well with the standard card of Rb2SrP2O7, indicating that the small amount of Ba substitution for Rb and Eu doping did not produce other impurity phases. The prepared yellow long-afterglow luminescent material...

[0032] It is a good single-phase sample.

[0033] Figure 2 The excitation and emission spectra of the yellow long-afterglow luminescent material prepared in Example 1 show that the emission wavelength range is 450 nm to 800 nm, and the emission peak is located at approximately 577 nm, belonging to the Eu range. 2+ 4f 6 5d 1 →4f 7 The transition was calculated using the CIE chromaticity diagram, and the chromatic coordinates of the emitted light from the long-afterglow luminescent material were found to be x=0.4612, y=0.5012, which are located in the yellow light emission region.

[0034] Figure 3 The afterglow spectra of the long afterglow luminescent material prepared in Example 1 were measured after irradiating it with a 254nm ultraviolet lamp for 10 minutes and then turning off the light source, respectively, at 30s and 900s. Figure 4 The graph shows the afterglow decay curve of the luminescent material. It can be seen from the graph that the luminescent material can continuously emit a human-eye-recognizable luminescence of 0.32 mcd / m² for more than 12 hours. 2 The above visible light has an initial afterglow brightness of 261.6 mcd / m². 2 .

[0035] Example 2

[0036] Press Rb 1.9 Ba 0.1 Sr 0.995 P2O7: 0.005Eu 2+ Based on the stoichiometric ratios shown in the molecular formula, 0.50728 g of Rb₂CO₃, 0.33963 g of SrCO₃, 0.04563 g of BaCO₃, 0.53191 g of NH₄H₂PO₄, and 0.00203 g of Eu₂O₃ were weighed out, thoroughly mixed, and ground to obtain raw material powder. The raw material powder was transferred to an alumina crucible and placed in a calcination furnace. A reducing atmosphere consisting of 25% hydrogen and 75% nitrogen by volume was introduced, and the mixture was calcined at 800℃ for 6 hours. After cooling to room temperature in the furnace, the calcined product was ground to obtain a yellow phosphate long-afterglow luminescent material. Afterglow testing was performed on this yellow long-afterglow luminescent material. After irradiation with a 254 nm ultraviolet lamp for 10 minutes and then turning off the light source, the initial afterglow brightness of the yellow long-afterglow luminescent material was 308.75 mcd / m².2 , persistence time 560 min.

Claims

1. A yellow phosphor long afterglow luminescent material, characterized by, The long afterglow luminescent material has a chemical formula of Rb 1.9 Ba 0.1 Sr 1-x P2O7: x Eu 2+ ; wherein 0.0025≤ x ≤0.

005.

2. A method for preparing the yellow phosphor long afterglow luminescent material of claim 1, characterized by, The preparation method is carried out according to the following steps: 1) according to the chemical formula Rb 1.9 Ba 0.1 Sr 1-x P2O7: x Eu 2+ stoichiometric ratio of each raw material, each raw material is weighed, wherein Rb is introduced by carbonate, Sr is introduced by carbonate, oxide or nitrate, Ba is introduced by carbonate, oxide or nitrate, P is introduced by NH4H2PO4 or (NH4)2HPO4, and Eu is introduced by Eu2O3; 2) The raw materials are ground and mixed to obtain raw material powder; the raw material powder is placed in a roasting furnace with a reducing atmosphere, and is roasted at a temperature of 800-1000 ℃ for 4-6 hours, and is cooled to room temperature with the furnace, and is ground to obtain a yellow phosphate long-afterglow phosphor.

3. The preparation method of the yellow phosphate long afterglow luminescent material as described in claim 2, characterized in that, In the step 2), the reducing atmosphere uses two kinds of mixed gas: the first kind is a mixed gas composed of 5-25% hydrogen and 95-75% nitrogen in percentage by volume; and the second kind is a mixed gas composed of 5-25% carbon monoxide and 95-75% nitrogen in percentage by volume.

4. The method for preparing the yellow phosphate long-afterglow luminescent material as described in claim 2, characterized in that, In the step 2), the temperature is raised to 800-1000 ℃ at a temperature raising rate of 5 ℃ / min.

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