A europium ion-doped germanate system luminescent material

Abstract

This invention discloses a europium ion-doped germanate luminescent material. The material has a germanate compound as its main structure, with trivalent europium ions introduced as luminescent centers. Its general chemical formula is: [formula omitted for brevity]; where represents the molar fraction of europium ions in the doping solution, and [formula omitted for brevity]. The material is prepared from sodium carbonate, calcium carbonate, germanium dioxide, and europium trioxide as starting materials through a high-temperature solid-state reaction according to the corresponding stoichiometric ratios. The trivalent europium ions are bound in a rigid germanate lattice, achieving red emission under excitation. This invention limits the doping amount to a specific range, balancing the concentration of luminescent centers and non-radiative energy transfer, avoiding lattice distortion and impurity phase derivation, and overcoming the thermal quenching defects of conventional luminescent materials under high-temperature conditions. This allows the material to maintain a stable structural state and luminescent response over a wide temperature range of 298K to 473K.

Description

Technical Field

[0001] This invention relates to the field of inorganic rare earth luminescent materials and solid-state light source technology, specifically to a europium ion-doped germanate system luminescent material. Background Technology

[0002] Inorganic luminescent materials are the fundamental carriers for solid-state lighting and novel display technologies, absorbing external excitation energy and converting it into visible light. Among luminescent material systems, red luminescent materials can improve the color rendering index and adjust the color temperature of light sources, making them an important component in the field of optoelectronic materials.

[0003] In industrial applications of solid-state light source devices, red luminescent materials are typically incorporated into the peripheral optical path components of excitation sources such as light-emitting diodes (LEDs) or laser diodes. After absorbing radiation generated by the excitation source, the material's internal luminescent centers undergo electronic energy level transitions, radiating a red spectrum to meet the light output requirements of terminal lighting or display devices.

[0004] As solid-state light-emitting devices (SLEDs) advance towards higher power, existing red luminescent materials face a technical drawback in applications: matrix structural instability leading to luminescence quenching under high-temperature conditions. Under sustained high operating temperatures, the matrix lattice of conventional materials is prone to microscopic deformation or localized thermal collapse, failing to provide a stable crystal field environment for the luminescent center ions. Deterioration of the matrix structure increases non-radiative transitions within the lattice, causing the luminescence intensity to decrease with increasing temperature. Consequently, the structural stability and luminescence-thermal stability of the luminescent materials under high-temperature service conditions cannot meet the requirements for application. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a europium ion-doped germanate system luminescent material, which solves the problems of luminescent thermal quenching and matrix structure degradation faced by inorganic red luminescent materials in high-power light-emitting device applications.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a europium ion-doped germanate system luminescent material, wherein the luminescent material uses a germanate compound as the main structure, and introduces trivalent europium ions as luminescent centers into the structure, with the general chemical formula being: ;in, This represents the mole fraction of europium ions doped, and .

[0007] Preferably, the trivalent europium ions replace some of the calcium ions in the matrix and bind to the rigid germanate lattice of the main structure to form red luminescent centers.

[0008] Preferably, the molar fraction x of europium ions is selected from any one of 0.025, 0.033, 0.05 or 0.1.

[0009] Preferably, the luminescent material is prepared by a high-temperature solid-state reaction of raw materials containing sodium, calcium, germanium and europium sources.

[0010] Preferably, the raw materials comprise sodium carbonate, calcium carbonate, germanium dioxide, and europium trioxide, and the stoichiometric ratio of each raw material is as follows: .

[0011] Preferably, the microstructure of the luminescent material is composed of irregular blocky grains.

[0012] Preferably, in the luminescent material element, element, element, Elements and The elements exhibit a uniform distribution at the microscopic level.

[0013] Preferably, when the mole fraction of dopant in the general chemical formula When the quantum efficiency is 0.0033, the quantum efficiency of the luminescent material is 47.57%.

[0014] Preferably, the luminescent material maintains a constant position of its characteristic emission peak within a temperature range of 298K to 473K.

[0015] This invention provides a europium ion-doped germanate system luminescent material. It possesses the following beneficial effects: 1. This invention introduces trivalent europium ions into a germanate compound matrix with a rigid framework structure to form crystals, enabling the luminescent centers to maintain a stable chemical state and physical occupancy in the matrix crystal field environment. This overcomes the defects of matrix lattice thermal collapse and luminescence performance decay that easily occur in luminescent materials under high-temperature service conditions, effectively suppresses the thermal quenching phenomenon caused by non-radiative transitions, and realizes the structural stability and luminescence thermal stability of europium ion-doped germanate luminescent materials under a wide temperature range of 298K to 473K.

[0016] 2. This invention controls the molar fraction of europium ions in the range of 0.025 to 0.1, ensuring that the number of luminescent centers in the crystal lattice is sufficient to guarantee the smooth transfer of excited-state energy in the crystal and output of luminescence response. At the same time, it avoids the problem of shortened rare-earth ion spacing caused by excessive doping concentration, prevents non-radiative energy transfer and local energy accumulation, and prevents excessive doping from causing distortion of the main crystal structure. This achieves a stable luminescence effect of the luminescent material while balancing the intensity of luminescence response and avoiding the derivation of impurity phase structures.

[0017] 3. This invention uses sodium carbonate, calcium carbonate, germanium dioxide, and europium trioxide in stoichiometric proportions as raw materials to undergo a solid-state reaction, which transforms the chemical composition of the corresponding elements into the target compound system and presents a uniform microscopic distribution. This ensures that trivalent europium ions are bound in the inorganic lattice framework, maintaining a reasonable radiative transition mechanism while preserving the target crystal phase structure. This allows the luminescent material to convert light energy into visible light under external excitation, achieving stable quantum efficiency and effective photoelectric conversion with high color purity red emission. Attached Figure Description

[0018] Figure 1 Different in Embodiment 1 of the present invention X-ray diffraction (XRD) patterns of doped samples; Figure 2 This is a scanning electron microscope (SEM) image of the red luminescent material obtained in Example 2 of the present invention; Figure 3 This is a mapping diagram of the elemental distribution of the red luminescent material obtained in Example 3 of the present invention; Figure 4 This is the full X-ray photoelectron spectroscopy (XPS) spectrum of the red luminescent material obtained in Example 3 of the present invention; Figure 5 The photoluminescence spectrum of the red luminescent material obtained in Example 4 of this invention is a temperature-dependent photoluminescence spectrum. Figure 6 This is a quantum efficiency diagram of the red luminescent material obtained in Example 5 of the present invention; Figure 7 The XRD pattern of the red luminescent material obtained in Comparative Example 1; Figure 8 The following are excitation spectra of the red luminescent materials obtained in Examples 1-5 and Comparative Example 2 of this invention; Figure 9 The emission spectra of the red luminescent materials obtained in Examples 1-5 and Comparative Example 2 of this invention are shown. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see the appendix Figure 1This invention provides a europium ion-doped germanate system red luminescent material. The luminescent material uses a germanate compound as the main structure, and introduces trivalent europium ions as luminescent centers into the structure. Its general chemical formula is [chemical formula not provided]. ,in, This represents the mole fraction of europium ions doped, and The luminescent material is prepared by a high-temperature solid-state reaction of raw materials containing sodium, calcium, germanium, and europium sources. The raw materials include sodium carbonate, calcium carbonate, germanium dioxide, and europium trioxide, and the stoichiometric ratio of each raw material is as follows: .

[0021] trivalent europium ion ( The calcium ion enters the rigid germanate lattice in a trivalent form and enters the calcium lattice site of the rigid germanate lattice. By forming a small number of sodium ion vacancies, charge balance is achieved, thereby forming a stable luminescent center in the matrix. This overcomes the thermal quenching phenomenon under high temperature conditions and achieves stable red emission. The structure and performance of the luminescent material are described below with reference to specific embodiments and comparative examples.

[0022] Example 1

[0023] This embodiment provides four different sets of... Red luminescent materials with doped content, mole fraction of doping The values ​​are 0.025, 0.033, 0.05, and 0.1, respectively.

[0024] The raw materials used in the first group of luminescent materials are: sodium carbonate 0.10g, calcium carbonate 0.10g, germanium oxide 0.21g, and europium trioxide 0.018g. The raw materials used in the second group of luminescent materials are: sodium carbonate 0.10g, calcium carbonate 0.10g, germanium oxide 0.21g, and europium trioxide 0.023g. The raw materials used in the third group of luminescent materials are: sodium carbonate 0.10g, calcium carbonate 0.10g, germanium oxide 0.21g, and europium trioxide 0.035g. The raw materials used in the fourth group of luminescent materials are: sodium carbonate 0.10g, calcium carbonate 0.10g, germanium oxide 0.21g, and europium trioxide 0.07g.

[0025] The above-mentioned raw materials were mixed and subjected to a high-temperature solid-state reaction to obtain a bulk material. After crushing and grinding, luminescent materials with corresponding doping ratios were obtained. X-ray diffraction (XRD) tests were performed on the four groups of luminescent materials, and the results are as follows: Figure 1 As shown, the tests indicate that the diffraction peak positions and relative intensities of the four groups of luminescent materials are basically consistent with the standard diffraction data of the target crystalline phase, and no obvious impurity phase peaks were observed, proving that in Within the range, the introduction of europium ions did not affect The main crystal structure has a significant impact.

[0026] Example 2

[0027] This embodiment provides a chemical composition of The luminescent material was prepared by mixing the following raw materials: europium trioxide 0.018g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g. The luminescent material was prepared by mixing the raw materials and reacting them in a high-temperature solid-state environment.

[0028] The prepared luminescent material was tested using a scanning electron microscope (SEM), and the results are as follows: Figure 2 As shown, the luminescent material is composed of several irregular blocky grains with clear grain outlines and relatively dispersed grain size distribution. The morphological characteristics prove that the luminescent material has completed the full crystallization process, which is conducive to the stable introduction and distribution of europium ions in the matrix.

[0029] Example 3

[0030] This embodiment provides a chemical composition of The luminescent material was prepared by mixing the following raw materials: europium trioxide 0.023g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g. The luminescent material was prepared by mixing the raw materials and reacting them in a high-temperature solid-state reaction.

[0031] Elemental mapping and X-ray photoelectron spectroscopy (XPS) analysis were performed on the luminescent materials, such as... Figure 3 As shown, the constituent elements such as Ca, O, Na, and Ge were all detected and exhibited a uniform distribution. Figure 4 As shown, the characteristic peaks of the corresponding elements in the XPS full spectrum of the luminescent material are clear, the binding energy positions are consistent with the theoretical values, and no impurity element signals are detected, proving that the elemental composition of the obtained luminescent material is correct and the purity is high.

[0032] Example 4

[0033] This embodiment provides a chemical composition of The luminescent material was prepared by mixing the following raw materials: europium trioxide 0.035g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g. The luminescent material was prepared by mixing the raw materials and reacting them in a high-temperature solid-state environment.

[0034] The thermal stability of the luminescent material was characterized using a variable-temperature photoluminescence assay, such as... Figure 5 As shown, when the excitation conditions are kept consistent within the temperature range of 298K to 473K, although the luminescence intensity changes accordingly with temperature, the characteristic emission peak remains clearly distinguishable and the position of the emission peak does not change significantly. This proves that the crystal structure of the luminescent material remains stable under varying temperature conditions and has good luminescence thermal stability.

[0035] Example 5

[0036] This embodiment provides a chemical composition of The luminescent material was prepared by mixing the following raw materials: europium trioxide 0.07g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g. The luminescent material was prepared by mixing the raw materials and reacting them in a high-temperature solid-state reaction.

[0037] The luminescence properties of luminescent materials are characterized by quantum efficiency testing, such as... Figure 6 As shown, the luminescent material can effectively convert light energy into visible light, and the quantum efficiency (QY) was measured to be 47.57%, which is the highest value among all doped samples in this experiment, proving that the luminescent material system maintains a reasonable radiative transition process and has stable luminescent performance.

[0038] Comparative Example 1 This comparative example provides the target composition as follows: The luminescent material was prepared using the following raw materials: europium trioxide 0.14g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g, in the same manner as in Example 1.

[0039] like Figure 7 The XRD pattern shows that when the europium ion doping concentration increases to When the doping concentration is 0.2, excessive doping has an adverse effect on the stability of the matrix crystal structure, resulting in the appearance of impurity phase structures in the sample.

[0040] Comparative Example 2 This comparative example provides the chemical composition as follows: The luminescent material was prepared using the following raw materials: europium trioxide 0.014g, sodium carbonate 0.10g, calcium carbonate 0.10g, and germanium oxide 0.21g, in the same manner as in Example 1.

[0041] Comprehensive Comparative Analysis of Material Luminescence Properties Excitation spectra of the luminescent materials prepared in Examples 1 to 5 and Comparative Example 2 were obtained. Figure 8 ) and emission spectrum ( Figure 9 ) Test, combined with the test results, under the same preparation and testing conditions, when the europium ion doping concentration is low ( When the doping concentration is 0.02, the number of luminescent centers is limited, the energy transfer process of the excited state in the crystal lattice is restricted, and the luminescence response is relatively weak. As the doping concentration increases... Within a certain range, rare earth ions are uniformly introduced into the matrix lattice, resulting in smooth energy transfer and a relatively stable trend in luminescence performance with high luminescence intensity. However, when the doping amount further increases beyond this range (as in Comparative Example 1), the luminescence performance deteriorates. If the doping concentration is 0.2, it will induce nonradiative energy transfer and local energy accumulation, leading to concentration quenching and destruction of the crystal structure. Therefore, controlling the doping concentration is crucial. This is a direct technical requirement for obtaining crystal phase stability and excellent luminescence response.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A europium ion-doped germanate system luminescent material, characterized in that, The luminescent material uses a germanate compound as its main structure, with trivalent europium ions introduced into the structure as luminescent centers. Its general chemical formula is: ;in, This indicates the mole fraction of europium ions doped, and .

2. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The trivalent europium ions replace some of the calcium ions in the matrix and bind to the rigid germanate lattice of the main structure to form red luminescent centers.

3. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The mole fraction of europium ions doped Choose from any one of 0.025, 0.033, 0.05 or 0.

1.

4. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The luminescent material is prepared by a high-temperature solid-state reaction of raw materials containing sodium, calcium, germanium and europium sources.

5. The europium ion-doped germanate system luminescent material according to claim 4, characterized in that, The raw materials include sodium carbonate, calcium carbonate, germanium dioxide, and europium trioxide, and the stoichiometric ratio of each raw material is as follows: .

6. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The microstructure of the luminescent material consists of irregular blocky grains.

7. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The luminescent material element, element, element, Elements and The elements exhibit a uniform distribution at the microscopic level.

8. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, When the mole fraction of doping in the general chemical formula When the quantum efficiency is 0.0033, the quantum efficiency of the luminescent material is 47.57%.

9. The europium ion-doped germanate system luminescent material according to claim 1, characterized in that, The luminescent material maintains a constant position of its characteristic emission peak within a temperature range of 298K to 473K.

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