Lutetium-gadolinium-gallium garnet-based broadband near-infrared fluorescent powder with ultrahigh luminescence thermal stability and preparation method thereof

Abstract

The invention discloses lutetium-gadolinium-gallium garnet-based broadband near-infrared fluorescent powder with ultrahigh luminescence thermal stability, which is Cr < 3 + > doped Lu2GdGa5O12 near-infrared fluorescent powder, the chemical composition of the fluorescent powder is Lu2GdGa5O12: xCr < 3 + >, x is the concentration of doped Cr < 3 + >, x is more than 0 and less than or equal to 1, the fluorescent powder can be excited by 250-320 nm ultraviolet light, 360-530 nm blue-green light and 550-700 nm red light, the emission peak covers 600-850 nm, and the emission peak is more than 0 and less than or equal to 1. According to the present invention, the blue-light-emitting near-infrared light conversion material has characteristics of high light emitting intensity, excellent light emitting thermal stability, simple synthesis and the like, can be used in the fields of high-power near-infrared LED devices, plant illumination and the like, and can be used as the near-infrared light conversion material excited by the blue-light LED chip, and the blue-light-emitting near-infrared light conversion material has characteristics of high light emitting intensity, excellent light emitting thermal stability and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic luminescent materials, in particular to a lutetium gadolinium gallium garnet-based broadband near-infrared fluorescent powder with super-high luminescent thermal stability and a preparation method thereof. BACKGROUND

[0002] Near-infrared (NIR) spectroscopy technology has attracted much attention due to its wide applications in food detection, biomedical imaging, night vision lighting, and spectral analysis. As the core component of NIR light source, the performance of near-infrared light-emitting diode (NIR LED) directly determines the efficiency of the entire system. However, commercial NIR LEDs are usually based on gallium arsenide (GaAs) semiconductor materials, which have a narrow emission spectrum half-width (usually ~ 30 nm), making it difficult to meet the demand for broadband light sources, which to some extent limits its application in scenarios requiring wide spectral analysis (such as component identification). To solve the above problems, the device scheme of "blue LED chip + near-infrared fluorescent powder" has been proven to be an effective and economical strategy. This scheme uses a blue chip to excite a fluorescent powder, thereby obtaining a wider near-infrared emission. Therefore, the development of near-infrared fluorescent powder with high luminescent efficiency, broadband emission, and stable physical and chemical properties has become the focus of research in this technical field.

[0003] Among the many material systems, garnet structure fluorescent powder activated by rare earth ions (general formula A3B5O 12 ) has been widely studied due to its stable structure, stable physical and chemical properties, and mature synthesis process. Among them, Cr 3+ ions are commonly used near-infrared luminescent activators, which can produce broadband emission from 650 nm to 1200 nm through the 4 T2→ 4 A2 transition in the octahedral site. However, Cr 3+ doped garnet system fluorescent powder (such as gadolinium gallium garnet GGG:Cr 3+ , yttrium gallium garnet YAG: 3+ , etc.) generally has a key defect: poor thermal stability. During the operation of the device, the heat generated by the chip can cause the temperature of the fluorescent powder to rise sharply, causing severe thermal quenching effect, resulting in a significant decrease in luminescent intensity, which directly affects the output power, reliability, and service life of the NIR LED device.

[0004] Therefore, there is an urgent need in the art to develop new near-infrared fluorescent powder. SUMMARY

[0005] The purpose of the present application is to provide a lutetium gadolinium gallium garnet-based broadband near-infrared fluorescent powder with super-high luminescent thermal stability and a preparation method thereof, which solves the problem of poor luminescent thermal stability performance in the prior art.

[0006] This invention is achieved through the following technical solutions:

[0007] A broadband near-infrared phosphor based on lutetium gadolinium gallium garnet with ultra-high luminescence and thermal stability, which is Cr 3+ Lu2GdGa5O doped 12 Near-infrared phosphor, its chemical composition is Lu2GdGa 5-x O 12 :xCr 3+ Where x is the Cr dopant 3+ The concentration is such that 0 < x ≤ 1, preferably 0 < x ≤ 0.1.

[0008] The preparation method of the lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence and thermal stability includes the following steps: weighing raw materials containing lutetium, gadolinium, gallium and chromium elements according to their chemical composition, wherein the stoichiometric ratio of the metal elements lutetium, gadolinium, gallium and chromium is 2:1:5-x:x, 0<x≤1, grinding and mixing thoroughly, placing in a reaction vessel, sintering at 1425-1450℃ in an air atmosphere, cooling to room temperature, and grinding to obtain the target phosphor.

[0009] Preferably, the sintering step is as follows: the temperature is increased from room temperature to 1450°C at a rate of 3-5°C / min, and then held at a constant temperature for 4-8 hours after the temperature increase is completed.

[0010] Preferably, the raw material containing lutetium is selected from one or more of lutetium oxide, lutetium oxalate, lutetium carbonate, and lutetium nitrate.

[0011] Preferably, the raw material containing gadolinium is selected from one or more of gadolinium oxide, gadolinium oxalate, gadolinium carbonate, and gadolinium nitrate.

[0012] Preferably, the raw material containing gallium is selected from gallium oxide.

[0013] Preferably, the raw material containing chromium is selected from one or more of chromium oxide and chromium nitrate.

[0014] The lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor of this invention exhibits excellent luminescence and thermal stability, which is tunable. Its luminescence intensity increases with temperature between 25-300℃ (298-573K), reaching a maximum of 402% at room temperature at 275℃, far superior to similar Cr phosphors. 3+ Materials doped with near-infrared luminescent phosphors, such as Cr 3+ Gd3Ga5O doped 12 Phosphor (Comparative Example 1), Cr in Comparative Example 1 3+ Gd3Ga5O doped 12 The luminescence intensity of phosphors gradually decreases as the temperature increases.

[0015] Therefore, the application also protects the application of the above-mentioned Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder with ultrahigh luminescence thermal stability in high-power light-emitting devices. Generally, the more power a device has, the more heat it releases when working, thus leading to an increase in the temperature of the device; and the luminescence intensity of the fluorescent powder generally decreases with the increase in temperature, i.e. luminescence thermal quenching. The Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder of the application presents an abnormal thermal quenching phenomenon, and its luminescence intensity continuously increases with the increase in temperature between 25-275℃ (298-548K), thus better solving the above-mentioned problems, and thus being suitable for high-power light-emitting devices with a power of 1 W or more, such as high-power near-infrared LEDs.

[0016] The application also protects the application of the above-mentioned Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder with ultrahigh luminescence thermal stability in the field of plant growth lighting.

[0017] The application also protects the application of the above-mentioned Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder with ultrahigh luminescence thermal stability as a near-infrared light conversion material excited by a blue LED chip.

[0018] Compared with the prior art, the application has the following beneficial effects:

[0019] (1) The Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder of the application can be excited by ultraviolet light of 250-320 nm, blue-green light of 360-530 nm, and red light of 550-700 nm, and has an emission peak covering 600 nm to 850 nm, and a broadband emission peak at 735 nm, and the half-peak width value increases with the increase in temperature between 25-300℃ (298-573K).

[0020] (2) The Lu-Gd-Ga garnet-based broadband near-infrared fluorescent powder of the application has the advantages of high luminescence intensity, very excellent luminescence thermal stability, and simple synthesis, and can be used in the fields of high-power near-infrared LED devices and plant lighting, and can be applied as a near-infrared light conversion material excited by a blue LED chip. Its luminescence intensity increases with the increase in temperature between 25-275℃ (298-548K), and at 150℃, it can reach 248% of that at room temperature, and at 275℃, it can reach 402% of that at room temperature, which is the highest value reported at present, and is much better than the same type of Cr 3+ doped near-infrared luminescent fluorescent powder material; the same type of Cr 3+ doped Gd3Ga5O 12 The luminescence intensity of the near-infrared fluorescent powder gradually decreases with the increase in temperature, and at 150℃, its luminescence intensity is only 30-50% of that at room temperature. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the Cr3+ The fluorescence emission spectrum of the Lu-Cr-Ga-Sn garnet-based near-infrared fluorescent powder; according to the fluorescence emission spectrum, the emission peak covers 600 nm to 850 nm, and the wideband emission peak is at 735 nm.

[0022] Figure 2 Cr prepared in Example 2 3+ The fluorescence excitation spectrum of the Lu-Cr-Ga-Sn garnet-based near-infrared fluorescent powder; according to the fluorescence excitation spectrum, the fluorescent powder can be excited by ultraviolet light of 250-320 nm, blue-green light of 360-530 nm, and red light of 550-700 nm.

[0023] Figure 3 Cr prepared in Example 3 3+ The X-ray powder diffraction pattern of the Lu-Cr-Ga garnet-based wideband near-infrared fluorescent powder; according to the XRD pattern, the substance is a pure phase.

[0024] Figure 4 Cr prepared in Example 1 3+ The temperature-dependent half-peak width graph of the Lu-Cr-Ga garnet-based wideband near-infrared fluorescent powder at 25-300℃ (298-573K); the half-peak width value gradually increases with increasing temperature.

[0025] Figure 5 Cr prepared in Example 1 3+ The temperature-dependent fluorescence intensity normalization graph of the Lu-Cr-Ga garnet-based wideband near-infrared fluorescent powder at 25-300℃ (298-573K); the luminescence intensity gradually increases before the temperature reaches 275℃.

[0026] Figure 6 Cr prepared in Example 1 and Comparative Example 1 3+ The temperature-dependent luminescence intensity trend graph of the Lu-Cr-Ga garnet-based wideband near-infrared fluorescent powder. DETAILED DESCRIPTION

[0027] The following is a further description of the present application, but not a limitation of the present application.

[0028] Example 1

[0029] Lu2O3) 1.5917 g, Gd2O3) 0.7250 g, Ga2O3) 1.8707 g, and Cr2O3) 0.0030 g were weighed, uniformly ground in an agate mortar, placed in a corundum crucible, and heated from room temperature to 1450℃ at a rate of 3-5℃ / min in a normal pressure air atmosphere, kept at the preset temperature for 6 hours, and then naturally cooled to obtain Lu2GdGa4.99 O 12 :0.01Cr 3+ Near-infrared fluorescent powder.

[0030] Example 2

[0031] Lu2GdGa2O7:0.01Cr 4.95 O 12 :0.05Cr 3+ Near-infrared fluorescent powder.

[0032] Example 3

[0033] Lu2GdGa2O7:0.05Cr 4.90 O 12 :0.10Cr 3+ Near-infrared fluorescent powder.

[0034] Comparative Example 1

[0035] Gd3Ga5O12:0.01Cr 4.99 O 12 :0.01Cr 3+ Near-infrared fluorescent powder.

Claims

1. A lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence and thermal stability, characterized in that, For Cr 3+ Lu2GdGa5O doped 12 Near-infrared phosphor, its chemical composition is Lu2GdGa 5-x O 12 :xCr 3+ Where x is the Cr dopant 3+ The concentration of x is such that 0 < x ≤ 1.

2. A method for preparing the lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence and thermal stability as described in claim 1, characterized in that, Includes the following steps: Raw materials containing lutetium, gadolinium, gallium, and chromium are weighed according to their chemical composition, wherein the stoichiometric ratio of lutetium, gadolinium, gallium, and chromium is 2:1:5-x:x, 0<x≤1. The raw materials are thoroughly ground and mixed evenly, sintered in air at 1425-1450℃, cooled to room temperature, and ground again to obtain the target phosphor.

3. The preparation method according to claim 2, characterized in that, The sintering step is as follows: the temperature is increased from room temperature to 1450℃ at a rate of 3-5℃ / min, and then held at a constant temperature for 4-8 hours after the heating is completed.

4. The preparation method according to claim 2, characterized in that, Raw materials containing lutetium are selected from one or more of lutetium oxide, lutetium oxalate, lutetium carbonate, and lutetium nitrate.

5. The preparation method according to claim 2, characterized in that, Raw materials containing gadolinium are selected from one or more of gadolinium oxide, gadolinium oxalate, gadolinium carbonate, and gadolinium nitrate.

6. The preparation method according to claim 2, characterized in that, The raw materials containing gallium are selected from gallium oxide.

7. The preparation method according to claim 2, characterized in that, The raw materials containing chromium are selected from one or more of chromium oxide and chromium nitrate.

8. The application of the lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence thermal stability as described in claim 1 in high-power light-emitting devices with a power of 1W or more.

9. The application of the lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence thermal stability as described in claim 1 in the field of plant growth lighting.

10. The application of the lutetium-gadolinium-gallium garnet-based broadband near-infrared phosphor with ultra-high luminescence thermal stability as described in claim 1 as a near-infrared light conversion material excited by a blue LED chip.

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