A pentavalent manganese-doped silicate-based near-infrared luminescent powder material and a preparation method thereof

Abstract

The application discloses a pentavalent manganese-doped silicate-based near-infrared luminescent powder material and a preparation method thereof, and belongs to the field of inorganic near-infrared luminescent materials. 1‑x O4:xMn 5+ wherein A is at least one of Li and Na, B is at least one of Ca, Sr and Ba, and 0.15%<=x<=15%; the near-infrared luminescent powder material is prepared by high-temperature solid-phase sintering, and has the advantages of simple process, low cost, non-toxicity, non-pollution and suitability for industrialized batch production. The near-infrared luminescent powder material can effectively absorb visible light and realize long-wavelength near-infrared emission, the emission peak can be finely controlled in the range of 1093-1169nm by adjusting A / B site cations, the emission spectrum band covers 1000-1400nm, the luminescent internal quantum efficiency is as high as 97%, and the near-infrared luminescent powder material has excellent chemical stability and thermal stability.

Description

Technical Field

[0001] This invention belongs to the field of inorganic near-infrared luminescent materials, specifically relating to a pentavalent manganese-doped silicate-based near-infrared luminescent powder material and its preparation method. Background Technology

[0002] With the rapid development of optoelectronic technology, near-infrared (NIR, 700–2500 nm) light sources have shown broad application prospects in cutting-edge fields such as bioimaging, anti-counterfeiting identification, pressure sensing, and luminescent thermometry. Currently, mainstream near-infrared light sources mainly rely on two types of solutions: one is semiconductor LEDs such as InGaAs, and the other is near-infrared fluorescent conversion LED (pc-LED) devices made by composite encapsulating LED chips with near-infrared luminescent powder materials. However, semiconductor LED solutions have limitations such as poor thermal stability, narrow wavelength tuning range, and difficulty in accurately matching biological windows. For near-infrared pc-LED light sources, near-infrared luminescent materials are key to determining device performance, but they still suffer from shortcomings such as low luminous quantum efficiency and poor thermal stability. Especially in the near-infrared II band with wavelengths greater than 1000 nm, there is still a lack of efficient long-wavelength emission systems. Therefore, there is an urgent need to develop efficient, long-wavelength, spectrally tunable, and thermally stable near-infrared luminescent materials.

[0003] Meanwhile, near-infrared luminescent powder materials can be used as inorganic pigments, exhibiting excellent heat resistance, light resistance, weather resistance, moisture resistance, and acid and alkali resistance. However, their unique near-infrared emission characteristics have received relatively little attention. Effectively utilizing their high near-infrared emissivity can significantly reduce heat accumulation in the matrix material, making them more suitable as cold pigments for thermal management applications, achieving dual regulation of optical and thermal properties. Furthermore, most existing high-efficiency near-infrared luminescent systems require the use of precious elements such as gallium, scandium, indium, and tantalum, resulting in high synthesis costs and hindering large-scale industrial synthesis, thus significantly impacting the commercial application of near-infrared luminescent powder materials. Summary of the Invention

[0004] The purpose of this invention is to provide a low-cost, long-wavelength emission, high-efficiency, and high-thermal-stability near-infrared luminescent powder material system and its preparation method. The luminescent powder material of this invention can be used in near-infrared PC-LEDs and high-performance inorganic cold pigments. This material exhibits excellent near-infrared II emission performance, possessing the dual advantages of high-efficiency luminescence and bright color: on the one hand, it can be used as a high-efficiency near-infrared (NIR) luminescent material for near-infrared light sources; on the other hand, due to its strong absorption characteristics in the visible light region and the resulting vibrant color, it can be used as a high-performance inorganic cold pigment in the field of thermal management.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A type of Mn 5+Doped silicate-based near-infrared luminescent powder material, with the chemical formula A2BSi 1-x O4:xMn 5+ Where A is at least one of Li and Na, and B is at least one of Ca, Sr and Ba, and 0.15%≤x≤15%.

[0006] The preparation method of the above-mentioned near-infrared luminescent powder material includes the following steps: (1) According to the corresponding chemical formula, take the oxygen-containing compounds of raw materials A, B, and Mn or their corresponding salts, add the reaction flux, and mix them thoroughly in a mortar and grind them to obtain a mixture; (2) After the mixture is poured into the corundum crucible, it is placed in a tube furnace for calcination. The calcined product is then transferred to a mortar and ground again to obtain the target near-infrared luminescent powder material.

[0007] Furthermore, in step (1), the flux is one or more alkali metal fluorides.

[0008] Furthermore, in step (1), the amount of flux used is 0.5% to 5% of the total weight of the raw materials.

[0009] Further, in step (2), the burning conditions are: temperature 800~1100℃, time 3~6h, heating rate 3~10℃ / min, and high-purity oxygen atmosphere is introduced at the same time.

[0010] Further, in step (2), pre-sintering is performed before the burning: temperature 500~600℃, time 2~4h, heating rate 3~10℃ / min.

[0011] Further, in step (2), the calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the final product.

[0012] The luminescent powder material of this invention is selected from transition metal ions Mn 5+ As an activating ion, its 3d 2 The electronic configuration endows the material with unique near-infrared narrowband luminescence properties. Meanwhile, Mn... 5+ Preferring to occupy tetrahedral sites, its low-symmetry crystal field results in strong absorption in the visible light region, giving it a bright color appearance. Furthermore, manganese, as an essential trace element for the human body, possesses excellent biocompatibility and environmental friendliness. In addition, silicates, with their advantages of low cost, diverse structures, low synthesis temperature, and environmental friendliness, have become a preferred choice for loading Mn. 5+ The ideal substrate for Mn. However, currently... 5+ Research on doped near-infrared materials is still in its early stages. Limited by bottlenecks such as valence instability and poor thermal stability, there is a lack of materials that combine high luminous efficiency and excellent thermal stability, especially high-efficiency silicate-based Mn.5+ The luminescent systems are even more scarce. This invention uses a high-temperature solid-state method to prepare a series of A2BSi... 1-x O4:xMn 5+ A luminescent material, wherein A is at least one of Li and Na, and B is at least one of Ca, Sr, and Ba, with 0.15% ≤ x ≤ 15%. By changing the cations at the A / B sites, the crystal structure of the matrix lattice and Mn can be effectively controlled. 5+ -O 2- By leveraging the covalent nature of the bonds, the emission peak can be precisely shifted from 1093 nm to 1169 nm.

[0013] Compared with the prior art, the present invention has the following specific beneficial effects: 1) The silicate matrix system of the present invention has simple and readily available components, low cost, non-toxic and pollution-free, and the preparation process is simple and easy to operate, making it easy to scale up industrial production and with broad market prospects.

[0014] 2) This invention modulates the luminescence performance of near-infrared luminescent materials by changing the A / B site cations, achieving fine shift control of the emission peak from 1093nm to 1169nm. Moreover, the material can be effectively excited by visible light and has the characteristics of long emission wavelength, tunable emission peak, high thermal stability, and high quantum efficiency. It can be used to construct near-infrared II fluorescent conversion LED devices.

[0015] 3) The Mn involved in this invention 5+ Doped silicate materials exhibit strong absorption in the visible light region, displaying a vibrant blue body color. Simultaneously, they possess high emissivity in the near-infrared region, effectively radiating heat energy, making them suitable for constructing novel blue cold pigments. Crucially, these pigments are non-toxic, containing no traditional heavy metals such as lead, chromium, or cobalt, making them human- and environmentally friendly, fully compliant with increasingly stringent global green chemistry standards. This combination of superior optical performance, thermal management capabilities, and ecological safety gives them immense commercial value in green building, automotive coatings, and outdoor facilities. Attached Figure Description

[0016] Figure 1 The images show physical photos of the near-infrared luminescent powder materials obtained in Examples 1, 3, and 9 of this invention.

[0017] Figure 2 The X-ray diffraction patterns of Examples 1, 3, 7, 8, and 9 of this invention and their corresponding A2BSi values ​​are shown below. 0.9975 O4:0.25%Mn 5+ (where A is at least one of Li and Na, and B is at least one of Ca, Sr, and Ba) Standard PDF comparison.

[0018] Figure 3The excitation and emission spectra are those of Embodiment 1 of the present invention.

[0019] Figure 4 This is the internal quantum efficiency spectrum of Embodiment 1 of the present invention.

[0020] Figure 5 The excitation and emission spectra are those of Embodiment 2 of the present invention.

[0021] Figure 6 The excitation and emission spectra are those of Embodiment 3 of the present invention.

[0022] Figure 7 This is the internal quantum efficiency spectrum of Embodiment 3 of the present invention.

[0023] Figure 8 This is the emission spectrum intensity variation at different temperatures in Example 3 of the present invention.

[0024] Figure 9 The excitation and emission spectra are those of Embodiment 4 of the present invention.

[0025] Figure 10 The excitation and emission spectra are those of Embodiment 5 of the present invention.

[0026] Figure 11 The excitation and emission spectra are those of Embodiment 6 of the present invention.

[0027] Figure 12 The excitation and emission spectra are those of Embodiment 7 of the present invention.

[0028] Figure 13 This is the internal quantum efficiency spectrum of Embodiment 7 of the present invention.

[0029] Figure 14 The excitation and emission spectra are those of Example 8 of the present invention.

[0030] Figure 15 This is the internal quantum efficiency spectrum of Embodiment 8 of the present invention.

[0031] Figure 16 The excitation and emission spectra are those of Example 9 of the present invention.

[0032] Figure 17 This is the internal quantum efficiency spectrum of Embodiment 9 of the present invention.

[0033] Figure 18 The above are simulated solar radiation temperature rise diagrams for peacock blue pigment in Examples 1, 3, and 9 of this invention. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Example 1

[0037] A pentavalent manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂CaSi 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; CaCO₃: 0.8007g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0336g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground in the agate mortar with an appropriate amount of anhydrous ethanol for 10 minutes, and then returned to the corundum crucible. The mixture is then placed in a high-purity oxygen atmosphere tube furnace at 900℃ and calcined for 4 hours to obtain the calcined product.

[0038] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2CaSi of this invention. 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0039] A physical image of the near-infrared luminescent powder material in Example 1 is shown below. Figure 1 As shown, the relevant CIE LAB color parameters are L* = 76.35, a* = -4.62, b* = -4.52. Figure 2 The X-ray diffraction pattern of Example 1 is shown. The diffraction peak positions of this example are consistent with the PDF card (PDF#04-009-3902) of standard Li₂CaSiO₄, indicating that Example 1 is a pure-phase structure. The excitation and emission spectra of Example 1 are as follows: Figure 3 As shown, under 605 nm red light excitation, the emission spectrum of this embodiment exhibits two sharp emission peaks located at 1093 nm and 1105 nm, which are attributed to Mn. 5+ of 1 E→3 A2 transition (specifically corresponding to...) 1 (E1 and E2 states generated by E-level splitting); furthermore, under emission wavelength monitoring at 1105 nm, its excitation spectrum consists of three excitation bands located at 316 nm, 615 nm, and 708 nm, mainly originating from Mn. 5+ Mn 5+ -O 2- Charge transfer transition, 3 A2® 3 T1( 3 F) Electric dipoles allow for transitions and 3 A2® 1 A1 self-selected forbidden transition; the internal quantum efficiency graph of this embodiment is as follows: Figure 4 As shown, according to the formula for calculating internal quantum efficiency: Internal quantum efficiency = Total number of photons generated by the material / Total number of photons absorbed, the internal quantum efficiency of this near-infrared luminescent powder material is as high as 97% under 605 nm red light excitation. In addition, the absorption efficiency is 42.9% and the external quantum efficiency is 41.6%. Example 2

[0040] A pentavalent manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂CaSi 0.985 O4:1.5%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; CaCO₃: 0.8007g; SiO₂: 0.4734g; MnCO₃: 0.0138g; flux NaF: 0.0336g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground in the agate mortar with an appropriate amount of anhydrous ethanol for 10 minutes, and then returned to the corundum crucible. The mixture is then placed in a high-purity oxygen atmosphere tube furnace at 900℃ and calcined for 4 hours to obtain the calcined product.

[0041] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2CaSi of this invention. 0.985 O4:1.5%Mn 5+ Near-infrared luminescent powder materials.

[0042] The excitation and emission spectra of this embodiment are as follows: Figure 5 As shown in the figure, this embodiment can be excited by visible light in the range of 250-400nm and 500-850nm, emitting narrow-band near-infrared light in the range of 1000-1300nm. The spectrum is similar to that of Example 1, but the luminescence intensity is slightly reduced. Example 3

[0043] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂Sr 0.5 Ca 0.5 Si 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; SrCO₃: 0.5905g; CaCO₃: 0.4004g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0272g. Pour the above raw materials and flux together with an appropriate amount of anhydrous ethanol into an agate mortar and grind for 30 minutes to obtain a uniformly mixed material. Place the mixture into a corundum crucible and pre-calcine at a constant temperature of 600℃ for 2 hours. Pour the pre-calcined product into the agate mortar together with an appropriate amount of anhydrous ethanol and grind for 10 minutes. Then, return the mixture to the corundum crucible and calcine at a constant temperature of 900℃ in a high-purity oxygen atmosphere for 4 hours to obtain the calcined product.

[0044] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2Sr of this invention. 0.5 Ca 0.5 Si 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0045] A physical image of the near-infrared luminescent powder material in this embodiment is shown below. Figure 1 As shown, the relevant CIE LAB color parameters are L* = 76.08, a* = -11.99, b* = -13.64. X-ray diffraction pattern of Example 3 ( Figure 2 The results show a match with the standard Li4SrCaSi2O8 PDF card (PDF#04-025-9024), confirming that Example 3 is a pure phase. The excitation and emission spectra of Example 3 are as follows: Figure 6 As shown, under 630nm red light excitation, the emission spectrum of this embodiment mainly consists of a sharp emission peak at 1129nm, with a full width at half maximum (FWHM) of only 10nm. This emission peak is attributed to Mn. 5+ of 1 E→ 3 A2 transition; under emission wavelength monitoring of 1129 nm, its excitation spectrum consists of three excitation bands located at 322 nm, 630 nm, and 725 nm, respectively; the internal quantum efficiency spectrum of this embodiment is as follows. Figure 7As shown, this near-infrared luminescent material achieves an internal quantum efficiency of 73.5%, an absorption efficiency of 49.7%, and an external quantum efficiency of 36.5% under 630 nm red light excitation. The emission spectra at different temperatures are shown below. Figure 8 As shown, its integrated emission intensity remains at 73.5% of the room temperature intensity at 150°C. Example 4

[0046] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂Sr 0.5 Ca 0.5 Si 0.97 O4:3%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; SrCO₃: 0.5905g; CaCO₃: 0.4004g; SiO₂: 0.4662g; MnCO₃: 0.0276g; flux NaF: 0.0272g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground in the agate mortar with an appropriate amount of anhydrous ethanol for 10 minutes, and then returned to the corundum crucible. The mixture is then placed in a high-purity oxygen atmosphere tube furnace at 900℃ and calcined for 4 hours to obtain the calcined product.

[0047] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2Sr of this invention. 0.5 Ca 0.5 Si 0.97 O4:3%Mn 5+ Near-infrared luminescent powder materials.

[0048] The excitation and emission spectra of this embodiment are as follows: Figure 9 As shown in the figure, this embodiment can be excited by visible light in the range of 250-400nm and 500-850nm, and emits narrow-band near-infrared light in the range of 1000-1300nm. The emission peak is located at 1129nm. The spectrum is similar to that of Example 3, but the luminescence intensity is slightly reduced. Example 5

[0049] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂Sr 0.3 Ca 0.7 Si 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; SrCO₃: 0.3543g; CaCO₃: 0.5605g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0272g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes to obtain a uniformly mixed material. Place this mixture into a corundum crucible and pre-calcine at 600℃ in a tube furnace for 2 hours. Pour the pre-calcined product into the agate mortar with an appropriate amount of anhydrous ethanol and grind for 10 minutes. Then, return the mixture to the corundum crucible and calcine at 900℃ in a high-purity oxygen atmosphere for 4 hours to obtain the calcined product.

[0050] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2Sr of this invention. 0.3 Ca 0.7 Si 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0051] The excitation and emission spectra of this embodiment are as follows: Figure 10 As shown in the figure, this embodiment can be excited by visible light in the range of 250-400nm and 500-850nm, and emits narrow-band near-infrared light in the range of 1000-1300nm. The spectrum is similar to that of embodiment 3, but the emission peak is blue-shifted to 1123nm and the luminescence intensity is improved. Example 6

[0052] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂Sr 0.7 Ca 0.3 Si 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; SrCO₃: 0.8267g; CaCO₃: 0.2402g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0272g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes to obtain a uniformly mixed material. Place this mixture into a corundum crucible and pre-calcine at 600℃ in a tube furnace for 2 hours. Pour the pre-calcined product into the agate mortar with an appropriate amount of anhydrous ethanol and grind for 10 minutes. Then, return the mixture to the corundum crucible and calcine at 900℃ in a high-purity oxygen atmosphere for 4 hours to obtain the calcined product.

[0053] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2Sr of this invention. 0.7 Ca0.3 Si 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0054] The excitation and emission spectra of this embodiment are as follows: Figure 11 As shown in the figure, this embodiment can be excited by visible light in the range of 250-400nm and 500-850nm, exhibits narrow-band emission in the near-infrared band of 1000-1300nm, and the emission peak is split, forming a double characteristic peak located at 1129nm and 1136nm. Example 7

[0055] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂SrSi 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; SrCO₃: 1.1810g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0310g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes to obtain a uniformly mixed material. Place this mixture into a corundum crucible and pre-calcine at a constant temperature of 600℃ for 2 hours. Pour the pre-calcined product into the agate mortar with an appropriate amount of anhydrous ethanol and grind for 10 minutes. Then, return the mixture to the corundum crucible and calcine at a constant temperature of 850℃ in a high-purity oxygen atmosphere for 4 hours to obtain the calcined product.

[0056] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2SrSi of this invention. 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0057] The X-ray diffraction pattern of this embodiment ( Figure 2 The results matched the standard Li₂SrSiO₄ PDF card (PDF#04-028-0942), confirming that Example 7 was a pure phase. The excitation and emission spectra of Example 7 are as follows: Figure 12 As shown, under 645nm red light excitation, the emission spectrum of this embodiment exhibits two sharp emission peaks located at 1127nm and 1150nm, which are due to Mn 5+ of 1 E→ 3 The A2 transition splits, similar to Example 1; under emission wavelength monitoring at 1150 nm, its excitation spectrum consists of three excitation bands located at 316 nm, 645 nm, and 728 nm, respectively; the internal quantum efficiency spectrum of this example is as follows. Figure 13As shown, the near-infrared luminescent material achieves an internal quantum efficiency of 65.0%, an absorption efficiency of 43.7%, and an external quantum efficiency of 28.4% under 645nm red light excitation. Example 8

[0058] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Li₂BaSi. 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Li₂CO₃: 0.5911g; BaCO₃: 1.5787g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0390g. Pour the above raw materials and flux, along with an appropriate amount of anhydrous ethanol, into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground in the agate mortar with an appropriate amount of anhydrous ethanol for 10 minutes, and then returned to the corundum crucible. The mixture is then placed in a high-purity oxygen atmosphere tube furnace at 800℃ and calcined for 4 hours to obtain the calcined product.

[0059] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Li2BaSi of this invention. 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0060] The X-ray diffraction pattern of this embodiment ( Figure 2 The results matched the standard Li₂BaSiO₄ PDF card (PDF#04-016-8709), confirming that Example 8 was a pure phase. The excitation and emission spectra of Example 8 are as follows: Figure 14 As shown, under red light excitation at 675 nm, the excitation and emission spectra of this embodiment are similar to those of Embodiment 3, but compared to Embodiment 3, its emission peak is redshifted to 1169 nm, while the emission peak intensity is slightly reduced. At a monitoring wavelength of 1169 nm, its excitation spectrum consists of three excitation bands located at 323 nm, 675 nm, and 764 nm, respectively; the internal quantum efficiency spectrum of this embodiment is shown below. Figure 15 As shown, the near-infrared luminescent material achieves an internal quantum efficiency of 44.8%, an absorption efficiency of 44.3%, and an external quantum efficiency of 19.8% under 675nm red light excitation. Example 9

[0061] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Na₂CaSi 0.9975 O4:0.25%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Na₂CO₃: 0.8479g; CaCO₃: 0.8007g; SiO₂: 0.4794g; MnCO₃: 0.0023g; flux NaF: 0.0428g. Pour the above raw materials and flux together with an appropriate amount of anhydrous ethanol into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground together with an appropriate amount of anhydrous ethanol into an agate mortar for 10 minutes, and then returned to the corundum crucible. The mixture is then placed into a high-purity oxygen atmosphere tube furnace at 1100℃ and calcined for 3 hours to obtain the calcined product.

[0062] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Na2CaSi of this invention. 0.9975 O4:0.25%Mn 5+ Near-infrared luminescent powder materials.

[0063] A physical image of the near-infrared luminescent powder material in Example 9 is shown below. Figure 1 As shown, the relevant CIE LAB color parameters are L* = 79.12, a* = -16.44, b* = -18.55. The X-ray diffraction pattern of this embodiment (…) Figure 2 The results match the PDF card (PDF#00-024-1069) for standard Na2CaSiO4, confirming that Example 9 is a pure phase. The excitation and emission spectra of this example are as follows: Figure 16 As shown, under 650 nm red light excitation, the emission spectrum of this embodiment mainly exhibits a sharp emission peak at 1150 nm. Compared with Example 8, the luminescence intensity further decreases, and the full width at half maximum (FWHM) increases to 37 nm. The internal quantum efficiency spectrum of this embodiment is shown below. Figure 17 As shown, the near-infrared luminescent powder material achieves an internal quantum efficiency of 33.7%, an absorption efficiency of 57.0%, and an external quantum efficiency of 19.2% under 650nm red light excitation. Example 10

[0064] A manganese ion-doped silicate-based near-infrared luminescent powder material with the chemical elemental composition Na₂CaSi 0.85 O4:15%Mn 5+ The preparation steps are as follows: 1. Weigh the following raw materials: Na₂CO₃: 0.8479g; CaCO₃: 0.8007g; SiO₂: 0.4085g; MnCO₃: 0.1379g; flux NaF: 0.0428g. Pour the above raw materials and flux together with an appropriate amount of anhydrous ethanol into an agate mortar and grind for 30 minutes. The resulting uniformly mixed material is then placed into a corundum crucible and pre-calcined at 600℃ for 2 hours. The pre-calcined product is then ground together with an appropriate amount of anhydrous ethanol into an agate mortar for 10 minutes, and then returned to the corundum crucible. The mixture is then placed into a high-purity oxygen atmosphere tube furnace at 1100℃ and calcined for 3 hours to obtain the calcined product.

[0065] 2. The calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the Na2CaSi of this invention. 0.85 O4:15%Mn 5+ Near-infrared luminescent powder materials.

[0066] The excitation and emission spectra of this embodiment are similar to those of Embodiment 9. This embodiment can be excited by visible light in the range of 250–430 nm and 500–850 nm, and the emission range covers the near-infrared II region of 1000–1400 nm, with the emission peak still located at 1150 nm.

[0067] The temperature rise graphs of Examples 1, 3, and 9 and the control samples (CIE LAB color parameters L* = 71.07, a* = -15.16, b* = -23.72) under simulated sunlight irradiation conditions are shown below. Figure 18 As shown. The initial temperature was 22.3℃. The surface temperature changes of the four groups of samples showed similar trends: the temperature rose rapidly within the first 10 minutes of irradiation, and the heating rate slowed significantly and approached thermal equilibrium between 10 and 45 minutes. Specifically, at 10 minutes, the temperatures of Examples 1, 3, and 9 and the peacock blue pigment were 30.6℃, 32.2℃, 33.9℃, and 39.1℃, respectively; at 45 minutes, they rose to 31.9℃, 33.1℃, 34.7℃, and 39.8℃, respectively, corresponding to temperature increases of 9.6℃, 10.8℃, 12.4℃, and 17.5℃, respectively. The above results indicate that the series of A2BSi prepared by this invention... 1-x O4:xMn 5+ The luminescent powder material, with its high near-infrared emission characteristics, exhibits significant heat insulation effects while maintaining a vibrant blue color, surpassing traditional peacock blue pigments. The surface temperature control capability of this invention effectively blocks heat transfer to the substrate in practical applications, thereby significantly reducing building cooling energy consumption and mitigating material thermal stress aging. This aligns with the global trend of green building and energy conservation and emission reduction. Therefore, the high-performance cold pigment of this invention demonstrates enormous commercial value and broad market application prospects in the fields of cooling coatings, building energy-saving materials, and industrial insulation.

[0068] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A type of Mn 5+ Doped silicate-based near-infrared luminescent powder material, with the chemical formula A2BSi 1-x O4:xMn 5+ Where A is at least one of Li and Na, and B is at least one of Ca, Sr and Ba, and 0.15%≤x≤15%.

2. The Mn according to claim 1 5+ A method for preparing doped silicate-based near-infrared luminescent powder materials, characterized in that... Includes the following steps: (1) According to the corresponding chemical formula, take the oxygen-containing compounds of raw materials A, B, and Mn or their corresponding salts, add the reaction flux, and mix them thoroughly in a mortar and grind them to obtain a mixture; (2) After the mixture is poured into the corundum crucible, it is placed in a tube furnace for calcination. The calcined product is then transferred to a mortar and ground again to obtain the target near-infrared luminescent powder material.

3. The preparation method according to claim 2, characterized in that, In step (1), the reaction flux is one or more alkali metal fluorides.

4. The preparation method according to claim 2, characterized in that, In step (1), the amount of the reaction flux is 0.5% to 5% of the total weight of the raw materials.

5. The preparation method according to claim 2, characterized in that, In step (2), the calcination conditions are: temperature 800~1100℃, time 3~6h, heating rate 3~10℃ / min, and high-purity oxygen atmosphere is introduced at the same time.

6. The preparation method according to claim 2, characterized in that, In step (2), pre-sintering is performed before calcination: temperature 500~600℃, time 2~4h, heating rate 3~10℃ / min.

7. The preparation method according to claim 2, characterized in that, In step (2), the calcined product is thoroughly ground into powder and passed through a 200-mesh sieve to obtain the final product.

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