A high entropy negative thermal expansion luminescent material and preparation method thereof

Abstract

The present invention belongs to the technical field of thermal expansion materials and discloses a high entropy negative thermal expansion luminescent material and a preparation method thereof. 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 Preparation method: Select Al source, Sc source, In source, Yb source, Y source, Er source and Mo source as raw materials, and prepare the target product (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The stoichiometric molar ratio of Al: Sc: In: Yb: Y: Er: Mo is 0.392: 0.392: 0.392: 0.392: 0.392: 0.04: 3, and the mixture is weighed and ground to mix evenly. The obtained mixed powder is directly sintered or sintered after tableting at a temperature of 1000-1100 ° C for 5-10 h, and then cooled to room temperature to obtain the target product (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The present invention proposes a molecular formula (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The high entropy negative thermal expansion luminescent material overcomes the thermal quenching characteristics of the luminescent material within a certain temperature range.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal expansion materials, and in particular relates to a high-entropy negative thermal expansion luminescent material and a preparation method thereof. Background Art

[0002] Luminescent materials are widely used in modern applications such as lighting, displays, optical temperature sensing, luminescence conversion layers in solar cells, and bioimaging. However, the inevitable thermal quenching (TQ) of most fluorescent materials severely restricts their further application in high-power optical devices. Thermal quenching (TQ) is a key issue commonly faced by fluorescent materials in high-temperature environments. It causes the luminescence efficiency of the material to drop sharply with increasing temperature, greatly limiting the application of these materials in high-power or high-temperature operating environments, such as LED lighting, high-temperature detectors, and bioimaging. Therefore, improving the luminescence intensity at high temperatures is a challenging task, which has promoted the exploration and research of thermally quenched luminescent materials.

[0003] The phenomenon of thermal quenching (TQ) is significantly correlated with the rigidity of the crystal structure. Specifically, when the activator is located in a host material with higher rigidity, its luminescence intensity is significantly better than that in a flexible host. This is because the rigid structure effectively suppresses the occurrence of non-radiative relaxation processes, which are more frequent in flexible hosts and thus weaken the luminescence efficiency. In this context, negative thermal expansion (NTE) host materials offer unique advantages. As the temperature increases, these materials contract rather than expand, and this property gives them greater structural rigidity during the contraction process. This increased rigidity not only enhances the material's stability but also reduces potential emission losses of dopants at high temperatures, thereby protecting the integrity of the luminescence center. Therefore, NTE is considered an effective strategy to avoid the occurrence of TQ, opening up new avenues for improving the performance of luminescent materials in high-temperature environments.

[0004] High-entropy solid solution approaches, as a novel materials design strategy, have attracted widespread attention in recent years. When the concept of high entropy was introduced to ceramics, various high-entropy ceramics (HECs) structures, such as pyrochlore (or defective fluorite) and perovskite, were subsequently designed and developed. Compared to single-component ceramics, HECs exhibit excellent thermal stability, tunable thermal expansion properties, incredible phase stability, and low thermal conductivity. Currently, HECs' application research focuses primarily on thermal protection and corrosion prevention, with relatively few reports on their applications in the field of nanostructured luminescent materials (NTE). Among the numerous high-entropy ceramic systems, rock-salt high-entropy oxide ceramics are the earliest discovered and readily synthesized, resulting in extensive research and a well-established theoretical framework. Compared to other high-entropy materials, they also exhibit significant lattice distortion, resulting in relatively low thermal conductivity. This lattice distortion results in extremely low thermal conductivity and a high thermal expansion coefficient, effectively leveraging the NTE properties of high-entropy materials and avoiding the thermal quenching effect of luminescent materials. Summary of the Invention

[0005] In order to overcome the deficiencies in the prior art, the present invention aims to provide a high-entropy negative thermal expansion luminescent material and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A high entropy negative thermal expansion luminescent material, the molecular formula of which is (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 .

[0008] A method for preparing a high entropy negative thermal expansion luminescent material: selecting Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source as raw materials, and 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The stoichiometric molar ratio of Al: Sc: In: Yb: Y: Er: Mo is 0.392: 0.392: 0.392: 0.392: 0.392: 0.04: 3, and the mixture is weighed and ground to mix evenly. The obtained mixed powder is directly sintered or sintered after tableting at a temperature of 1000-1100 ° C for 5-10 h, and then cooled to room temperature to obtain the target product (Al 0.196 Sc 0.196 In 0.196Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 ;

[0009] Wherein, the Al source is Al2O3 or a precursor material that can be heated and decomposed to obtain Al2O3 at a temperature not higher than the sintering temperature;

[0010] The Sc source is Sc2O3 or a precursor material that can be heated and decomposed to obtain Sc2O3 at a temperature not higher than the sintering temperature;

[0011] The In source is In2O3 or a precursor material that can be heated and decomposed to obtain In2O3 at a temperature not higher than the sintering temperature;

[0012] The Yb source is Yb2O3 or a precursor material that can be heated and decomposed to obtain Yb2O3 at a temperature not higher than the sintering temperature;

[0013] The Y source is Y2O3 or a precursor material that can be heated and decomposed to obtain Y2O3 at a temperature not higher than the sintering temperature;

[0014] The Er source is Er2O3 or a precursor that can be heated and decomposed at a temperature not higher than the sintering temperature to obtain Er2O3;

[0015] The Mo source is MoO3 or a precursor material that can be heated and decomposed at a temperature not higher than the sintering temperature to obtain MoO3.

[0016] Preferably, the Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source are weighed in proportion and ground and mixed uniformly, and the obtained mixed powder is first directly pre-sintered or sintered after tableting, and then the pre-sintered product is ground and mixed uniformly, and then tableted and sintered for the second time; the pre-sintering temperature is 700~800℃ and the time is 5~10h, and the secondary sintering temperature is 1000~1100℃ and the time is 5~10h.

[0017] Preferably, the Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source are weighed in proportion and ground and mixed uniformly, and wet grinding is adopted. Ethanol is added during grinding, and the amount added is based on wetting the Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source.

[0018] Preferably, dry grinding is used when grinding and mixing the pre-sintered product uniformly.

[0019] Preferably, the purity of the Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source is 99-99.99 wt %.

[0020] Preferably, all sintering processes are performed at a heating rate of 3-10°C / min to reach the sintering temperature.

[0021] Preferably, all tablets involved are pressed into cylindrical green embryos with a diameter of 8 to 10 mm and a height of 3 to 6 mm.

[0022] Preferably, for all tableting processes, the tableting pressure is 4-10 MPa and the holding time is 2-5 min.

[0023] Beneficial effects:

[0024] (1) The present invention proposes a molecular formula (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The high entropy negative thermal expansion luminescent material was prepared, and its phase purity, thermal expansion properties and luminescence performance were studied. The results showed that (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 Luminescent materials that overcome the thermal quenching characteristics of luminescent materials within a certain temperature range;

[0025] (2) The high-entropy NTE luminescent material of the present invention has good thermal stability, simple preparation process, low cost, and is suitable for industrial production. It is expected to be widely used in high-end technical fields such as displays, optical temperature sensors, and luminescence conversion layers of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 Rietveld refinement pattern of room temperature XRD data.

[0027] Figure 2 :Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 Room temperature XRD pattern of .

[0028] Figure 3 : Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 Schematic diagram of the structure.

[0029] Figure 4 : Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The curve of relative length changing with temperature.

[0030] Figure 5 :Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The curve of relative length changing with temperature.

[0031] Figure 6 : Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 Temperature-dependent emission spectrum under 980 nm laser excitation (a) and a plot of the normalized emission intensity of the 522 nm green emission band versus temperature (b).

[0032] Figure 7 :Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 Temperature-dependent emission spectrum of the 522 nm green emission band under 980 nm laser excitation (a) and a plot of the normalized emission intensity versus temperature at 522 nm (b). DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions of the present invention in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1

[0035] Solid-phase preparation of high entropy negative thermal expansion luminescent materials (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 :

[0036] Select analytically pure Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3, MoO3 as raw materials, and adjust Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3, MoO3 according to the target product (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The stoichiometric molar ratio of Al: Sc: In: Yb: Y: Er: Mo is 0.392: 0.392: 0.392: 0.392: 0.392: 0.04: 3. The mixture is weighed and placed in an agate mortar. Anhydrous ethanol is added to moisten the mixture (the amount of anhydrous ethanol added is based on the amount of Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3 and MoO3). The mixture is ground for 2 h. The obtained mixed powder is placed in a crucible and heated in a muffle furnace. The temperature was raised to 700°C at a heating rate of 5°C / min, and the mixture was pre-sintered for 10 h in air. The mixture was cooled to room temperature in air. The pre-sintered powder was taken out and dry-ground. The ground powder was pressed into a cylindrical blank with a diameter of 8 mm and a height of 3 mm under a pressure of 10 MPa for 2 min. The cylindrical blank was placed in a crucible and heated to 1100°C in a muffle furnace at a heating rate of 5°C / min. The mixture was pre-sintered for 10 h in air. The mixture was cooled to room temperature in air to obtain a bulk sample (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 .

[0037] Comparative Example 1

[0038] (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The preparation method comprises the following steps:

[0039] Select analytically pure Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3 and MoO3 as raw materials, and precipitate Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3 and MoO3 according to the target product (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The stoichiometric molar ratio of Al: Sc: In: Yb: Y: Er: Mo = 0.5: 0.5: 0.5: 0.2: 0.28: 0.02: 3 was weighed and mixed, placed in an agate mortar, and moistened with anhydrous ethanol (the amount of anhydrous ethanol added was based on the amount of Al2O3, Sc2O3, In2O3, Yb2O3, Y2O3, Er2O3 and MoO3), and ground for 2 h. The obtained mixed powder was placed in a crucible and heated in a muffle furnace at 5 ° C / m The heating rate of in was raised to 700℃, and the temperature was kept for pre-sintering for 10h. The temperature was naturally cooled to room temperature in the air. The pre-sintered powder was taken out and dry ground. The ground powder was pressed into a cylindrical blank with a diameter of 8mm and a height of 3mm at a pressure of 10Mpa for 2min. The cylindrical blank was placed in a crucible and heated to 1000℃ in a muffle furnace at a heating rate of 5℃ / min. The temperature was kept for calcining for 10h. The temperature was naturally cooled to room temperature in the air to obtain a bulk sample (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 .

[0040] Product Characterization and Performance Testing

[0041] Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The Rietveld refinement pattern of the room temperature XRD of the sample is as follows Figure 1 As shown, (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The structure of In2Mo3O 12 (PDF: 04-017-8004) are consistent, belonging to the orthorhombic Pbcn space group. The XRD diffraction peaks are independent of each other and the half-height width is small, indicating that the sample has good crystallinity. In addition, the Rietveld refinement obtained at room temperature (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The lattice parameters are: a=13.50 Å, b=9.72Å, c=9.82 Å, and the lattice volume V=1288.73Å.

[0042] Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The room temperature XRD patterns of the samples are shown in Figure 2 The XRD diffraction peaks are independent of each other and have a small half-height width, indicating that the sample has good crystallinity. More importantly, (Al 0.25 Sc 0.25 In 0.2 5Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The XRD pattern of Sc2Mo3O 12 The results were in good agreement with the standard card (PDF#73-10), indicating that the target product was successfully prepared.

[0043] Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The structural diagram of the sample is shown in Figure 3 As shown, Al 3+ Sc 3+ 、In 3+ 、Yb 3+ 、Y 3+、Er 3+ With 6 O 2- The anions together form an octahedron with the cation as the center, Mo 6+ Cations with 4 O 2- Ionic composition is Mo 6+ The MoO4 tetrahedron and the Al / Sc / In / Yb / Y / ErO6 octahedron are connected by bridging oxygen atoms.

[0044] Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The curve of the relative length of the sample (i.e. dL / L0, where dL = length after expansion - original length L0, the same below) changing with temperature is shown in Figure 4 . (Al 0.196 Sc 0.196 In 0.196 Yb 0.196 Y 0.196 Er 0.02 )2Mo3O 12 The sample shows negative expansion behavior (-5.87×10 -6 K -1 ). In addition, the inflection point in the thermal expansion curve is due to the presence of trace amounts of crystalline water in the sample.

[0045] Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The curve of the relative length of the sample changing with temperature is shown in Figure 5 . (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 The sample shows near-zero thermal expansion behavior (α l =-0.8×10 -6 K -1 ).

[0046] Example 1 prepared (Al 0.196 Sc 0.196 In 0.196 Yb0.196 Y 0.196 Er 0.02 )2Mo3O 12 Temperature-dependent emission spectra of the sample under 980 nm laser excitation ( Figure 6 a). Figure 6 a 522nm green emission band (corresponding to Er 3+ Ionic 2 H 11 / 2 → 4 I 15 / 2 ) after normalizing the emission intensity, it was found that the intensity increased by about 1.6 times in the range of 300~400K, and the emission intensity increased significantly with further increase in temperature. Overall, the emission intensity increased by about 53.4 times in the range of 300~650K ( Figure 6 b) Overcoming the thermal quenching characteristics of the luminescent material.

[0047] Comparative Example 1 prepared (Al 0.25 Sc 0.25 In 0.25 Yb 0.1 Y 0.14 Er 0.01 )2Mo3O 12 Temperature-dependent emission spectra of the sample under 980 nm laser excitation ( Figure 7 a). Figure 7 a 522nm green emission band (corresponding to Er 3+ Ionic 2 H 11 / 2 → 4 I 15 / 2 ) after normalizing the emission intensity, it was found that the emission intensity decreased by about 3.7 times in the range of 5~650K ( Figure 7 b).

Claims

1. A high-entropy negative thermal expansion luminescent material, characterized by: Its molecular formula is (Al 0.196 Sc 0.196 In 0.196 Yb 0.19 6Y 0.196 Er 0.02 )2Mo3O 12 .

2. A method for preparing the high-entropy negative thermal expansion luminescent material according to claim 1, characterized in that: Select Al source, Sc source, In source, Yb source, Y source, Er source and Mo source as raw materials, and according to the target product (Al 0.196 Sc 0.196 In 0.196 Yb 0.19 6Y 0.196 Er 0.02 )2Mo3O 12 The stoichiometric molar ratio of Al: Sc: In: Yb: Y: Er: Mo is 0.392: 0.392: 0.392: 0.392: 0.392: 0.04: 3, and the mixture is weighed and ground to mix evenly. The obtained mixed powder is directly sintered or sintered after tableting at a temperature of 1000-1100 ° C for 5-10 h, and then cooled to room temperature to obtain the target product (Al 0.196 Sc 0.196 In 0.196 Yb 0.19 6Y 0.196 Er 0.02 )2Mo3O 12； Wherein, the Al source is Al2O3 or a precursor material that can be heated and decomposed to obtain Al2O3 at a temperature not higher than the sintering temperature; The Sc source is Sc2O3 or a precursor material that can be heated and decomposed to obtain Sc2O3 at a temperature not higher than the sintering temperature; The In source is In2O3 or a precursor material that can be heated and decomposed to obtain In2O3 at a temperature not higher than the sintering temperature; The Yb source is Yb2O3 or a precursor material that can be heated and decomposed to obtain Yb2O3 at a temperature not higher than the sintering temperature; The Y source is Y2O3 or a precursor material that can be heated and decomposed to obtain Y2O3 at a temperature not higher than the sintering temperature; The Er source is Er2O3 or a precursor that can be heated and decomposed at a temperature not higher than the sintering temperature to obtain Er2O3; The Mo source is MoO3 or a precursor material that can be heated and decomposed at a temperature not higher than the sintering temperature to obtain MoO3.

3. The method for preparing a high-entropy negative thermal expansion luminescent material according to claim 2, wherein: After weighing Al source, Sc source, In source, Yb source, Y source, Er source and Mo source in proportion and grinding and mixing them evenly, the obtained mixed powder is first pre-sintered directly or pre-sintered after tableting, and then the pre-sintered product is ground and mixed evenly, and then tableted and sintered again; the pre-sintering temperature is 700~800℃ and the time is 5~10h, and the secondary sintering temperature is 1000~1100℃ and the time is 5~10h.

4. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 2 or 3, wherein: When the Al source, Sc source, In source, Yb source, Y source, Er source and Mo source are weighed in proportion and ground and mixed evenly, wet grinding is adopted. Ethanol is added during grinding, and the amount added is based on wetting the Al source, Sc source, In source, Yb source, Y source, Er source and Mo source.

5. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 3, wherein: When the pre-sintered product is ground and mixed uniformly, dry grinding is adopted.

6. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 2 or 3, wherein: The purity of the Al source, Sc source, In source, Yb source, Y source, Er source, and Mo source is 99-99.99 wt %.

7. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 2 or 3, wherein: All sintering processes involved were heated to the sintering temperature at a heating rate of 3-10°C / min.

8. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 2 or 3, wherein: All tablets involved are pressed into cylindrical blanks with a diameter of 8~10mm and a height of 3~6mm.

9. The method for preparing a high entropy negative thermal expansion luminescent material according to claim 2 or 3, wherein: For all tablet pressing processes, the pressure is 4~10MPa and the holding time is 2~5min.

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