Stannate red long-afterglow fluorescent material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of preparation of fluorescent materials, and particularly discloses a stannate red long-afterglow fluorescent material as well as a preparation method and application thereof. The composition of the fluorescent material is CaxSr (1-x) SnO4: ySm < 3 + >, or CaxSr (1-x) SnO4: ySm < 3 + >, zGd < 3 + >, 0.25 < = x < = 0.75, 0.001 < = y < = 0.005, and 0.001 < = z < = 0.005, that is, the doping amount of Sm and Gd is 0.1-0.5% of the mass of the matrix CaxSr (1-x) SnO4. According to the stannate red long-afterglow fluorescent material disclosed by the invention, Ca element is adopted to replace part of Sr element to form a matrix CaxSr (1-x) SnO4 of a novel system, and Sm and Gd elements are doped in the matrix, so that the afterglow performance of the material is effectively improved, not only is excellent red light performance shown, but also the sustainable time of red afterglow is prolonged, the energy level sinks, and the energy efficiency is improved. The luminous efficiency and stability are improved, and the luminous life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of fluorescent materials, and particularly relates to a stannate red long-afterglow fluorescent material, a preparation method thereof and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] The progress of science and technology and the rising demand for high technologies have promoted the demand upgrade in the fields of lighting and security in our country, and have also driven the accelerated progress of materials science. In scenarios such as night lighting, safety signs and emergency evacuation indicators, conventional lighting devices expose many safety hazards and high energy consumption. The long-afterglow luminescent material, as an innovative solution, can accumulate light sources and continuously release light in the dark, ensuring long-term lighting protection and meeting the lighting requirements of special environments. Such materials operate without continuous power input, without the need to be equipped with batteries or external wires, greatly reducing energy consumption, conforming to the trend of green sustainability, and is expected to reduce the use of disposable lighting appliances and reduce the environmental burden.

[0004] Red long-afterglow materials, with their unique charm, shine brightly in the fields of lighting and safety. Red long-afterglow materials can absorb light and store energy and then slowly release red light in the dark, not only beautifying the night environment, but also providing a long-lasting and eye-catching guidance to enhance the visibility of safety signs. In addition, red light has good atmospheric penetration ability and can still maintain good visibility under harsh conditions such as fog and smoke, making it suitable for applications outdoors and in harsh environments. With the iteration of technology, the luminescent performance, stability and weather resistance of the materials are continuously improved, expanding the application boundaries, from emergency lighting to creative decoration, showing broad application potential. However, the luminescent performance of the current red long-afterglow materials is still limited, and the sustainable time of luminescence needs to be improved to better meet the applications in some special environments. Summary of the Invention

[0005] In view of the above problems, the present invention provides a stannate red long-afterglow fluorescent material, a preparation method thereof and an application thereof. This long-afterglow material effectively extends the time of light release and enhances the afterglow effect. Specifically, the technical solution of the present invention is as follows.

[0006] First of all, the present invention provides a stannate red long-afterglow fluorescent material, and its composition is Ca x Sr (1-x) SnO4: y Sm 3 + ,or Ca x Sr (1-x) SnO4:y Sm 3+ , z Gd 3+ , wherein: 0.25 ≤ x ≤ 0.75, 0.001 ≤ y ≤ 0.005, 0.001 ≤ z ≤ 0.005, that is, the doping amounts of Sm and Gd elements are both 0.1 - 0.5% of the relative molecular weight of the matrix Ca x Sr (1-x) SnO4.

[0007] Secondly, the present invention discloses a preparation method of the stannate red long - persistent fluorescent material, comprising the following steps: (1) Weigh the calcium source, strontium source, tin source, samarium source according to the stoichiometric ratio of Ca x Sr (1-x) SnO4: y Sm 3+ , or use calcium source, strontium source, tin source, samarium source, gadolinium source as raw materials. After mixing these raw materials, grind them to obtain a mixed powder for standby. x Sr (1-x) SnO4: y Sm 3+ , z Gd 3+ (2) Carry out calcination treatment on the mixed powder, and after completion, cool it to room temperature to obtain the fluorescent material.

[0008] (2) Further, in step (1), the calcium source includes at least one of calcium carbonate, calcium oxide, etc.

[0009] (2) Further, in step (1), the strontium source includes at least one of strontium carbonate, strontium oxide, etc.

[0010] (2) Further, in step (1), the tin source includes tin dioxide, etc. The samarium source includes samarium sesquioxide, etc. The gadolinium source includes gadolinium oxide, etc.

[0011] (2) Further, in step (1), the grinding time is 3 - 5 hours and the grinding rate is 1000 - 1500 rpm.

[0012] (2) Further, in step (2), the calcination treatment method is: first heat up to 600 - 800 °C and keep warm for 3 - 5 hours, then continue to raise the temperature to 1000 - 1400 °C and keep warm for 3 - 5 hours. After completion, cool it to room temperature at a rate not higher than 5 °C / min.

[0013] (2) Further, in step (2), the calcination treatment method is: first heat up to 600 - 800 °C and keep warm for 3 - 5 hours, then continue to raise the temperature to 1000 - 1400 °C and keep warm for 3 - 5 hours. After completion, cool it to room temperature at a rate not higher than 5 °C / min.

[0014] Finally, the present invention discloses the application of the stannate red long-afterglow fluorescent material in emergency indication signs, night vision displays, decorative lighting, safety signs, toys, clock hands, anti-counterfeiting marks, biomedical marks, etc.

[0015] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: In the stannate red long-afterglow fluorescent material of the present invention, calcium (Ca) element is used to replace part of strontium (Sr) element to form a matrix Ca of a new system x Sr (1-x) SnO4, thereby effectively improving the afterglow performance of the material. It not only exhibits excellent red light performance, but also increases the sustainable time of red afterglow, and the energy level sinks, thereby reducing non-radiative transitions, enabling more excitation energy to be used for luminescence, and thus improving the luminescence efficiency. At the same time, it is also beneficial to extend the luminescence lifetime and stability of the fluorescent material. Meanwhile, the present invention also doped samarium (Sm) and gadolinium (Gd) elements in the new matrix, thereby: utilizing the rich 4f electron energy levels of the samarium element to support transitions between multiple energy levels to emit light of different wavelengths. Especially in the visible light range, after the samarium element is doped into Ca x Sr (1-x) SnO4 matrix, the 4 G 5 / 2 → 6 H J (J = 5 / 2, 7 / 2, 9 / 2) energy level transitions can occur to emit light, thereby achieving luminescence coverage in the red-orange light region and strengthening the ability of the red light emitted by the fluorescent material of the present invention. In the present invention, the gadolinium element does not directly participate in luminescence, but as a luminescence regulating ion, it occupies a specific energy level in the matrix of the new system by using its unfilled 4 f electron layer, thereby changing the electron cloud distribution of surrounding atoms, and thus affecting the symmetry and intensity of the crystal field. This change can lead to energy level splitting, forming a new energy level structure, which helps to form or adjust luminescence centers and trap centers, thereby promoting energy transfer and storage, extending the time of light release, and enhancing the afterglow effect. At the same time, the gadolinium element captures and stores excited-state electrons or holes using the trap points formed in the matrix, coordinates the interaction between the luminescence center and the trap, delays the speed of electrons returning to the ground state, extends the luminescence time, and enhances the afterglow effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0017] Figure 1Scanning electron micrograph of the stannate red long afterglow fluorescent material prepared for Example 1 below.

[0018] Figure 2 Scanning electron micrograph of the stannate red long afterglow fluorescent material prepared for Example 4 below.

[0019] Figure 3 Afterglow performance test chart of the fluorescent materials prepared for Examples 1-3 and Comparative Groups 1 and 2 below.

[0020] Figure 4 Excitation spectrum diagram of the fluorescent materials prepared for Example 1 and Examples 4-6 below.

[0021] Figure 5 Emission spectrum diagram of the fluorescent materials prepared for Example 1 and Examples 4-6 below.

[0022] Figure 6 Afterglow performance test chart of the fluorescent materials prepared for Example 2 and Examples 4-6 below.

[0023] Figure 7 Afterglow decay curve diagram of the fluorescent materials prepared for Example 1 and Example 4 below. Detailed implementation mode

[0024] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually in accordance with conventional conditions or the conditions recommended by the manufacturer.

[0025] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can all be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or in accordance with the product instructions.

[0026] In addition, any methods and materials similar or equivalent to the recorded content can be applied to the method of the present invention. The technical solution of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0027] Example 1 A preparation method of a stannate red long afterglow fluorescent material includes the following steps: (1) According to Ca 0.5 Sr 0.5 SnO4: 0.003Sm 3+For the stoichiometric ratio, accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling jar containing an appropriate amount of absolute ethanol, then place the ball milling jar on a planetary ball mill and grind at a speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0028] (2)Rinse the inner wall of the ball milling jar and the grinding balls with deionized water, mix the obtained cleaning solution with the mixed powder, and dry in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it to 800 °C at a rate of 5 °C / min and hold for 4 h, then heat it to 1200 °C at a rate of 5 °C / min and hold for 4 h, and after completion, heat it to room temperature at a rate of 5 °C / min to obtain the fluorescent material (as Figure 1 shown).

[0029] Example 2 A preparation method of a stannate red long afterglow fluorescent material includes the following steps: (1)According to the stoichiometric ratio of Ca 0.25 Sr 0.75 SnO4: 0.005Sm 3+ accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling jar containing an appropriate amount of absolute ethanol, then place the ball milling jar on a planetary ball mill and grind at a speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0030] (2)Rinse the inner wall of the ball milling jar and the grinding balls with deionized water, mix the obtained cleaning solution with the mixed powder, and dry in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it to 600 °C at a rate of 5 °C / min and hold for 5 h, then heat it to 1000 °C at a rate of 5 °C / min and hold for 5 h, and after completion, heat it to room temperature at a rate of 5 °C / min to obtain the fluorescent material.

[0031] Example 3 A preparation method of a stannate red long afterglow fluorescent material includes the following steps: (1)According to the stoichiometric ratio of Ca 0.75 Sr 0.25 SnO4: 0.001Sm 3+For the stoichiometric ratio, accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling tank containing an appropriate amount of absolute ethanol, then place the ball milling tank on a planetary ball mill and grind it at a rotational speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0032] (2) Rinse the inner wall of the ball milling tank and the grinding balls with deionized water, mix the obtained cleaning solution with the mixed powder, and dry it in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind it until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it at a rate of 5 °C / min to 700 °C and hold for 3 h, then heat it at a rate of 5 °C / min to 1400 °C and hold for 3 h. After completion, cool it to room temperature at a rate of 5 °C / min to obtain the fluorescent material.

[0033] Example 4 A preparation method of a stannate red long afterglow fluorescent material, comprising the following steps: (1) According to the stoichiometric ratio of Ca 0.75 Sr 0.25 SnO4: 0.003Sm 3+ , 0.003Gd 3+ For the stoichiometric ratio, accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling tank containing an appropriate amount of absolute ethanol, then place the ball milling tank on a planetary ball mill and grind it at a rotational speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0034] (2) Rinse the inner wall of the ball milling tank and the grinding balls with deionized water, mix the obtained cleaning solution with the mixed powder, and dry it in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind it until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it at a rate of 5 °C / min to 600 °C and hold for 5 h, then heat it at a rate of 5 °C / min to 1000 °C and hold for 5 h. After completion, cool it to room temperature at a rate of 5 °C / min to obtain the fluorescent material (as Figure 2 shown).

[0035] Example 5 A preparation method of a stannate red long afterglow fluorescent material, comprising the following steps: (1) According to the stoichiometric ratio of Ca 0.75 Sr 0.25 SnO4: 0.003Sm 3+ , 0.001Gd 3+For the stoichiometric ratio, accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling jar containing an appropriate amount of absolute ethanol, then place the ball milling jar on a planetary ball mill and grind at a speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0036] (2) Rinse the inner wall of the ball milling jar and the grinding balls with deionized water, and mix the obtained cleaning solution with the mixed powder and dry it in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind it until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it to 800 °C at a rate of 5 °C / min and hold for 4 h, then heat it to 1200 °C at a rate of 5 °C / min and hold for 4 h, and after completion, heat it to room temperature at a rate of 5 °C / min to obtain the fluorescent material.

[0037] Example 6 A preparation method of a stannate red long-afterglow fluorescent material, comprising the following steps: (1) According to the stoichiometric ratio of Ca 0.75 Sr 0.25 SnO4:0.003Sm 3+ ,0.005Gd 3+ , accurately weigh calcium carbonate, strontium carbonate, tin dioxide, and samarium sesquioxide as raw materials using an analytical balance. Mix the weighed raw materials of each group into a ball milling jar containing an appropriate amount of absolute ethanol, then place the ball milling jar on a planetary ball mill and grind at a speed of 1250 rpm for 4 h, and then pour out the mixed powder.

[0038] (2) Rinse the inner wall of the ball milling jar and the grinding balls with deionized water, and mix the obtained cleaning solution with the mixed powder and dry it in an oven for 12 h. Subsequently, pour the mixed powder into an agate mortar and grind it until there are no obvious large particles, then transfer it to a crucible and place it in a muffle furnace. First, heat it to 800 °C at a rate of 5 °C / min and hold for 4 h, then heat it to 1200 °C at a rate of 5 °C / min and hold for 4 h, and after completion, heat it to room temperature at a rate of 5 °C / min to obtain the fluorescent material.

[0039] Figure 1 and Figure 2 are the scanning electron microscope images (SEM) of the fluorescent materials prepared in Example 1 and Example 4 above, respectively. It can be seen that the prepared fluorescent materials exhibit excellent dispersibility and crystallization quality, and are morphologically similar to a porous dispersed structure, and the particle size distribution is uniform. Most of the particle diameters are concentrated around 2 μm, and no significant agglomeration phenomenon is observed.

[0040] Figure 3 are for Example 1 - 3 above and Comparative Group 1 (Sr0.75 SnO4:0.005Sm 3+ ), Comparative Group 2 (Ca 0.25 SnO4:0.005Sm 3+ ). The figure shows the afterglow performance test of the prepared fluorescent materials. After the samples to be tested are irradiated under ultraviolet lamps with wavelengths of 254 nm and 365 nm for ten minutes, the results after removing the light for 30 s, 1 min, and 3 min are shown from left to right. It can be seen from the figure that the afterglow performance of the fluorescent materials prepared in Examples 1-3 is better than that of the two comparative groups.

[0041] Figure 4 and Figure 5 are the excitation spectra (PLE) and emission spectra (PL) of the fluorescent materials prepared in Example 1 and Examples 4-6, respectively. The test samples are tested on an RF-6000 fluorescence spectrophotometer at a scanning speed of 200 nm / min. The PLE investigation range is from 200 to 400 nm, and the PL investigation range is from 330 to 550 nm. It can be seen that the afterglow effect of the fluorescent materials prepared in Examples 4-6 is better than that of Example 1. Figure 6 is the afterglow performance test figure of the fluorescent materials prepared in Example 2 and Examples 4-6 above. After the samples to be tested are irradiated under ultraviolet lamps with wavelengths of 254 nm and 365 nm for ten minutes, the results after removing the light for 30 s, 1 min, and 3 min are shown from left to right. It can be seen from the figure that the afterglow performance of the fluorescent materials prepared in Examples 4-6 is better than that of Example 2. This is because gadolinium uses its unfilled 4f electron layer to occupy a specific energy level in the matrix of the new system, thereby changing the electron cloud distribution of the surrounding atoms, which affects the symmetry and intensity of the crystal field. This change can lead to energy level splitting, forming a new energy level structure, which helps to form or adjust the luminescence center and trap center, thereby promoting energy transfer and storage, prolonging the time of light release, and enhancing the afterglow effect. At the same time, the gadolinium element uses the trap points formed in the matrix to capture and store excited electrons or holes, coordinates the interaction between the luminescence center and the trap, delays the speed of electrons returning to the ground state, prolongs the luminescence time, and enhances the afterglow effect.

[0042] Figure 7The figure shows the afterglow decay curves of the fluorescent materials prepared in the above Embodiment 1 and Embodiment 4. The testing instrument used is a steady-state / transient fluorescence spectrometer (model FLS1000) from Edinburgh, UK. After the sample to be tested is co-irradiated under ultraviolet lamps with wavelengths of 254 nm and 365 nm for ten minutes, the afterglow decay is detected at a wavelength of 648 nm. The testing step size is 0.2 s and the slit is 1 nm. It can be seen from the figure that after the light source is turned off, as time increases, the afterglow decay rate of the fluorescent material in Embodiment 4 is lower than that in Embodiment 1. This is because the addition of Gd element increases the trap energy level, and by adjusting the crystal field environment, trap concentration and depth, the afterglow intensity of the fluorescent material is further enhanced.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A stannate red long afterglow fluorescent material, characterized in that: The composition of this material is Ca x Sr (1-x) SnO4: y Sm 3 + , or Ca x Sr (1-x) SnO4: y Sm 3+ , z G 3+ , where: 0.25≤ x ≤0.75,0.001≤ y ≤0.005, 0.001≤ z ≤0.

005.

2. The method for preparing the stannate red long afterglow fluorescent material according to claim 1, characterized in that: The steps include: (1) According to the Ca x Sr (1-x) SnO4: y Sm 3+ , or Ca x Sr (1-x) SnO4: y Sm 3+ , z G 3+ Weighing a calcium source, a strontium source, a tin source, and a samarium source in a stoichiometric ratio, or using a calcium source, a strontium source, a tin source, a samarium source, and a gadolinium source as raw materials, mixing the raw materials and grinding them to obtain a mixed powder for later use; (2) The mixed powder is calcined and then cooled to room temperature to obtain the fluorescent material.

3. The method for preparing the stannate red long afterglow fluorescent material according to claim 2, characterized in that: In step (1), the calcium source includes at least one of calcium carbonate, calcium oxide, etc.

4. The method for preparing the stannate red long afterglow fluorescent material according to claim 2, characterized in that: In step (1), the strontium source includes at least one of strontium carbonate, strontium oxide, etc.

5. The method for preparing the stannate red long afterglow fluorescent material according to claim 2, characterized in that: In step (1), the tin source includes at least one of tin dioxide and the like.

6. The method for preparing the stannate red long afterglow fluorescent material according to claim 2, characterized in that: In step (1), the samarium source includes at least one of samarium trioxide and the like.

7. The method for preparing the stannate red long afterglow fluorescent material according to claim 2, characterized in that: In step (1), the gadolinium source includes at least one of gadolinium oxide and the like.

8. The method for preparing the stannate red long afterglow fluorescent material according to any one of claims 2 to 7, characterized in that: In step (1), the grinding time is 3 to 5 hours, and the grinding rate is 1000 to 1500 rpm.

9. The method for preparing the stannate red long afterglow fluorescent material according to any one of claims 2 to 7, characterized in that: In step (2), the calcination treatment is carried out by first raising the temperature to 600-800°C and keeping it for 3-5 hours, then continuing to raise the temperature to 1000-1400°C and keeping it for 3-5 hours, and after completion, raising the temperature to room temperature at a rate not higher than 5°C / min.

10. Use of the stannate red long afterglow fluorescent material according to claim 1, or the stannate red long afterglow fluorescent material obtained by the preparation method according to any one of claims 2 to 9 in emergency signs, night vision displays, decorative lighting, safety signs, toys, clock hands, anti-counterfeiting marks or biomedical marks.

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