Gd2O2S: Tb < 3 + > / CQDs composite luminescent material and preparation method thereof
By chemically bonding Gd2O2S:Tb3+ phosphor with carbon quantum dots (CQDs), using quantum confining effect and fluorescence resonance energy transfer (FRET), the problem of insufficient luminous intensity of Gd2O2S:Tb3+ phosphor in the prior art was solved, and a significant increase in luminous intensity was achieved.
Patent Information
- Application Number
- CN202510457170.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-13
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, research on improving luminescence performance by compounding carbon quantum dots with Gd2O2S:Tb3+ fluorescent materials has not been reported yet. How to improve the luminescence intensity of Gd2O2S:Tb3+ phosphor is still a challenge.
Gd2O2S:Tb3+ phosphor was synthesized by vulcanization and melting method, and carbon quantum dots (CQDs) were prepared by one-step pyrolysis method, and then hydrothermal recombination with Gd2O2S:Tb3+ phosphor. The quantum confining effect of carbon quantum dots and fluorescence resonance energy transfer (FRET) were used to enhance the excitation efficiency of Tb3+.
The luminous intensity of Gd2O2S:Tb3+ phosphor was significantly improved, which was increased by 19%, and the crystal structure stability of the material was maintained.
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Figure CN120290182A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a Gd2O2S:Tb 3+ / CQDs (carbon quantum dots) composite luminescent material and its preparation technology. This technology obtains the Gd2O2S:Tb 3+ phosphor bonded with CQDs through chemical bonds to obtain the Gd2O2S:Tb 3+ / CQDs composite luminescent material, which significantly improves the luminescence intensity of the Gd2O2S:Tb 3+ phosphor and belongs to the field of optoelectronic functional materials. Background Art
[0002] Rare earth luminescent materials have currently been widely used in different fields. Luminescent materials with Gd2O2S as the matrix doped with rare earth ions have advantages such as good luminescence performance, high conversion rate, strong absorption ability, and low phonon energy, and have become an ideal luminescent material matrix. Gd2O2S:Tb 3+ luminescent material, as a typical representative of advanced functional material systems, can emit light under various excitation sources such as X-rays, cathode rays, ultraviolet rays, and high-energy particles. Therefore, it plays an important role in many fields such as high-resolution computed tomography detectors, low-light level image intensifiers, neutron radiography technology, X-ray intensifying screens, and scintillation detectors.
[0003] In recent years, researchers have enhanced the luminescence efficiency and achieved performance optimization through process optimization, formulation regulation, material compounding, etc. MingMing Xing et al. prepared monodisperse spherical Gd2O2S:Tb 3+ nanoparticles by using an improved homogeneous precipitation method combined with a solid-gas sulfidation technique. Compared with the Gd2O2S:Tb 3+ nanoparticles prepared by the complex precipitation method, the obtained samples have excellent luminescence performance, and the luminescence intensity is increased by about 50% at a lower sulfidation temperature. Yu-Jie Ding et al. synthesized Gd2O2S:Tb 3+ phosphor with higher luminescence intensity than commercially prepared Gd2O2S:Tb 3+ phosphor by using commercial Gd2O3 and Gd2O(CO3)2·H2O precursor prepared by the homogeneous precipitation method to synthesize Gd2O3. Qilin Zou et al. proposed a kind of Ln 3+doped oxysulfide@fluoride core / shell heterostructures, which show efficient upconversion luminescence properties under 980nm excitation and good stability in solution. By epitaxial heterogeneous growth, a ~4nm optically inert β-NaYF4 shell was coated onto a ~5nm Gd2O2S:20%Yb,1%Tm, and the intensity of the UCL increased by more than 800 times compared with the core alone. Dengfeng Yang et al. based on α-NaYF4 along Gd2O2S:Ln 3+ Through the c-axis epitaxial growth of nanocrystals, a new core / shell heterostructure with tunable size and composition was designed. 3+ ions, achieving efficient and multicolor upconversion and downconversion luminescence under single-wavelength excitation, with significantly enhanced intensity compared to the core alone.
[0004] So far, the optimization of Gd2O2S:Tb 3+ There are many methods to study the luminescence performance. However, the research on the luminescence performance of carbon quantum dots (CQDs) and Gd2O2S:Tb 3+ Fluorescent materials composite to improve Gd2O2S:Tb 3+ The research on luminescence properties has not been reported. Carbon quantum dots are a type of nanoparticles with a diameter of less than 10nm. In 2004, Xu et al. first discovered CQDs in the process of separating and purifying single-walled carbon nanotubes, which triggered subsequent research. In 2006, Sun et al. prepared carbon nanoparticles with fluorescent properties by laser ablation of graphite powder and cement. Unlike most semiconductor quantum dot materials, CQDs have a low production cost, excellent photostability, low toxicity and chemical stability, and the fluorescence intensity of carbon dots is high and the stability is good when placed for a long time.
[0005] Based on this, the present invention has found a Gd2O2S:Tb 3+ / CQDs composite luminescent material and its preparation technology, the composite luminescent material significantly improves the Gd2O2S:Tb 3+ The luminous intensity of the phosphor. Summary of the invention
[0006] The present invention has found a Gd2O2S:Tb 3+ / CQDs composite luminescent material, the composition of which is Gd2O2S:Tb 3+ The phosphor and CQDs are chemically bonded to form. Preparation process of composite luminescent materials: First, Gd2O2S:Tb is synthesized by sulfurization flux method. 3+ Phosphor, and then CQDs were prepared by one-step pyrolysis, and finally Gd2O2S:Tb 3+ The phosphor and CQDs were hydrothermally composited to obtain Gd2O2S:Tb3+ / CQDs composite luminescent material. Citric acid was selected as the carbon source and urea as the nitrogen source. The raw materials citric acid and urea were weighed according to the stoichiometric ratio, and green-emitting carbon dots were prepared by a one-step pyrolysis method. Then, the Gd2O2S:Tb 3+ phosphor prepared by the warm solid-phase method was mixed with a 5 mg / L CQDs solution in a beaker, stirred in the beaker for 1 - 4 h, and placed in a reaction kettle and kept warm in an oven at 120 - 180 °C for 8 - 16 h. Finally, the composite material was taken out, and after steps such as centrifugation and drying, the Gd2O2S:Tb 3 + / CQDs composite luminescent material was obtained. In this invention, on the one hand, CQDs can absorb light in the ultraviolet to visible light range and emit light of a specific wavelength through the quantum confinement effect, improving the luminescence efficiency. On the other hand, carbon quantum dots have broad-spectrum absorption characteristics and can efficiently capture the excitation light energy. When the emission spectrum of CQDs matches the absorption spectrum of Tb 3+ (such as the 4f→5d transition), the energy can be transferred from CQDs to Tb through fluorescence resonance energy transfer (FRET) 3+ , directly enhancing the excitation efficiency of Tb 3+ , thereby improving the luminescence performance of the Gd2O2S:Tb 3+ phosphor. Brief Description of the Drawings
[0007] Figure 1 is the XRD pattern of the Gd2O2S:Tb 3+ / CQDs composite luminescent material sample synthesized in this invention.
[0008] Figure 2 is the photoluminescence emission spectrum of the Gd2O2S:Tb 3+ / CQDs composite luminescent material sample and the Gd2O2S:Tb 3+ fluorescent material.
[0009] Figure 3 is the photoluminescence excitation spectrum of the Gd2O2S:Tb 3+ / CQDs composite luminescent material sample and the Gd2O2S:Tb 3+ fluorescent material. Detailed Description of the Embodiments
[0010] The specific process of the Gd2O2S:Tb 3+ / CQDs composite luminescent material in this invention is described in detail as follows:
[0011] (1) Using citric acid and urea as raw materials, place them in an agate mortar according to the stoichiometric ratio, mix evenly, grind thoroughly, put the evenly ground powder into a crucible, and place it in a constant temperature drying oven at 180 - 240 °C for 2 - 6 h to obtain a black carbon dot precursor.
[0012] (2) Grind the black carbon dot precursor into powder in an agate mortar, add it to a centrifuge tube containing 100 ml of deionized water, centrifuge for 3 - 15 min, take the supernatant, filter it through a 0.22 - um microporous filter membrane to obtain a transparent CQDs solution. Put the CQDs solution into a pre - treated dialysis bag, place the filled dialysis bag into a beaker containing deionized water, stir for 24 - 48 h, collect the liquid inside the dialysis bag, put this liquid into the refrigerator and freeze it into ice cubes, and then freeze - dry it to obtain purified carbon dots.
[0013] (3) Prepare a 5 mg / ml CQDs solution, mix the prepared Gd2O2S:Tb 3+ fluorescent material with the CQDs solution, stir in a beaker for 1 - 4 h, and put the evenly mixed solution into a reaction kettle and keep it warm in an oven at 120 - 180 °C for 8 - 16 h. Take out the composite material, and obtain Gd2O2S:Tb 3+ composite fluorescent material after centrifugation and drying.
[0014] Figure 1 The XRD pattern of the Gd2O2S:Tb 3+ / CQDs composite luminescent material sample is consistent with the diffraction peaks of the standard card PDF#26 - 1422, indicating that the CQDs composite does not affect the crystal structure of the Gd2O2S:Tb 3+ fluorescent material.
[0015] Figure 2 The photoluminescence emission spectrum of the Gd2O2S:Tb 3+ / CQDs composite luminescent material sample synthesized in this invention and the Gd2O2S:Tb 3+ fluorescent material. It can be seen that the CQDs do not change the emission peak position of the Gd2O2S:Tb 3+ fluorescent material. At 544 nm, the photoluminescence intensity of the Gd2O2S:Tb 3+ / CQDs composite fluorescent material sample synthesized in this invention is 19% higher than that of the Gd2O2S:Tb 3+ fluorescent material.
[0016] Figure 3 The Gd2O2S:Tb 3+ / CQDs composite luminescent material sample synthesized in this invention and the Gd2O2S:Tb 3+Photoluminescence excitation spectrum of the fluorescent material. The excitation spectrum of the sample is a broadband spectrum with a peak at 286 nm and can emit bright green light under ultraviolet excitation.
Claims
1. A Gd2O2S:Tb 3+ / CQDs composite luminescent material, which is composed of Gd2O2S:Tb 3+ phosphor and CQDs chemically bonded together.
2. Gd2O2S:Tb 3+ Preparation technology of Gd2O2S:Tb 3+ / CQDs composite luminescent materials. First, Gd2O2S:Tb 3+ phosphor is synthesized by a sulfurization flux method, then CQDs are prepared by a one-step pyrolysis method, and finally Gd2O2S:Tb 3+ phosphor and CQDs are subjected to hydrothermal composite treatment. During the composite process, Gd2O2S:Tb 3+ phosphor is mixed with 5 mg / L CQDs solution, stirred in a beaker for 1 - 4 h, placed in a reaction kettle and kept warm in an oven at 120 - 180 °C for 8 - 16 h. Finally, the composite material is taken out, and after steps such as centrifugation and drying, Gd2O2S:Tb / CQDs composite luminescent materials are obtained.