High-purity green light-emitting and high-optical temperature measurement sensitivity material and preparation method thereof

Abstract

The invention discloses a high-purity green luminescent and high-optical temperature measurement sensitivity material and a preparation method thereof, and belongs to the technical field of optical luminescent materials. The chemical general formula of the high-purity green luminescence and high-optical temperature measurement sensitivity material is NaBi < 0.89-x > Yb < 0.1 > Er < 0.01 > Ca < x > (MoO4) 2, x is equal to 0.01-0.10, the material is a tetragonal system, the space group is I41 / a, rare earth erbium ions (Er < 3 + >) are used as active ions, rare earth ytterbium ions (Yb < 3 + >) are used as sensitizing ions, and green up-conversion emission near 530 nm and 550 nm can be generated under near-infrared excitation; the Er < 3 + > upconversion green emission ratio and the green light purity are improved by introducing non-equivalent ions Ca < 2 + > to regulate and control a matrix lattice environment and a charge compensation state, and meanwhile, the optical temperature measurement sensitivity based on the thermal coupling energy level is remarkably enhanced, so that the Er < 3 + > upconversion green emission compound has potential and wide application value in the fields of high-purity green light emission and optical temperature measurement.

Description

Technical Field

[0001] This invention relates to the field of optical luminescent materials technology, and in particular to a high-purity green luminescent and high optical temperature-sensitivity material and its preparation method. Background Technology

[0002] Non-contact optical thermometry technology, due to its advantages such as fast response speed, resistance to electromagnetic interference, long-distance detection, and applicability to micro-spaces, has significant application prospects in fields such as high-temperature device monitoring, microelectronic thermal management, bioimaging, and micro-area temperature field measurement. Currently, fluorescence thermometry methods based on rare-earth ion upconversion luminescence (such as luminescence intensity ratio FIR thermometry) have attracted widespread attention. The principle typically utilizes the temperature change of the thermally coupled energy levels of rare-earth ions to cause the intensity ratio of two adjacent emission peaks to change with temperature, thereby sensing temperature changes. However, existing upconversion thermometric materials generally suffer from insufficient luminescence intensity, an unsatisfactory green-to-red light ratio leading to low color purity, a narrow effective temperature measurement range, and limited temperature sensitivity, which restricts their engineering applications in high-precision, highly interfering, or harsh environments.

[0003] In the upconversion luminescence system, rare earth ions Yb 3+ / Er 3+ Combination, due to Yb 3+ It has strong absorption capabilities in the near-infrared band and can be directed towards Er. 3+ It exhibits high energy transfer efficiency, enabling visible light upconversion emission under near-infrared excitation, and is therefore widely used in green luminescence and thermometry research. Typically, Er³ + The green emission of Yb is related to its thermally coupled energy level and can be used to construct a luminescence intensity ratio thermometry model. However, in real materials, processes such as nonradiative relaxation, defect quenching, energy backhaul, and multiphonon relaxation often weaken green light emission or introduce a strong red light component, leading to a decrease in green light purity and a smaller slope of the intensity ratio change with temperature, thus resulting in insufficient thermometric sensitivity. Furthermore, simply relying on adjusting Yb... 3+ / Er 3+ Concentration-based methods often lead to problems such as concentration quenching or decreased luminescence stability, making it difficult to simultaneously achieve high-purity green light output and high temperature sensitivity.

[0004] A search revealed a Chinese patent application, CN112375568A, published on February 19, 2021, which discloses a K3YF6 matrix upconversion luminescent material and its preparation method. This luminescent material can emit green light when excited by 980nm infrared light. However, in practical applications, its high temperature sensitivity is poor, making it difficult to meet the engineering applications in high-precision, strong interference, or harsh environments. Summary of the Invention

[0005] 1. The technical problem that the invention aims to solve To address the challenge of existing luminescent materials simultaneously achieving high-purity green light output and high optical temperature sensitivity, this invention provides a high-purity green luminescent material and its preparation method, which can improve Er... 3+ The proportion of green upconversion emission is increased to improve green light purity and significantly enhance the sensitivity of optical thermometry based on thermally coupled energy levels.

[0006] 2. Technical Solution To achieve the above objectives, the technical solution provided by this invention is as follows: This invention relates to a high-purity green luminescent and high optical temperature sensing sensitivity material, with the general chemical formula NaBi. 0.89- x Yb 0.1 Er 0.01 Ca x (MoO4)2, where, x = 0.01-0.10, it is a tetragonal crystal system with space group I41 / a, and is composed of rare earth erbium ions (Er 3+ ) as the activating ion, with rare earth ytterbium ions (Yb) 3+ ( ) is a sensitizing ion, which can produce green upconversion emission near 530 nm and 550 nm under near-infrared excitation; by introducing the non-equivalent ion Ca 2+ By modulating the matrix lattice environment and charge compensation state, Er can be improved. 3+ The green upconversion process improves the proportion of green emission and the purity of green light, while also significantly enhancing the sensitivity of optical temperature measurement based on thermally coupled energy levels.

[0007] Further materials, with NaBi 0.89 Yb 0.1 Er 0.01 Using the (MoO4)2 complex as a matrix, the Ca ions are regulated by the unit cell. 2+ The doping modulates the cell structure.

[0008] Further materials, cell-controlled ions Ca 2+ The doping concentration is 3 at.

[0009] Further, the material exhibits a minimum green luminescence purity of 96.0% and a maximum optical thermometric relative sensitivity of 1.282% K. -1 The highest absolute sensitivity for optical temperature measurement is 1.793%K. -1 .

[0010] Further materials exhibit optical thermometry relative sensitivity and optical thermometry absolute sensitivity in the temperature range of 300 K-460 K.

[0011] A method for preparing the above-mentioned material includes the following steps: Weigh out the high-purity raw materials Na2CO3, Bi2O3, MoO3, Yb2O3, Er2O3, and other materials that can provide Ca according to the stoichiometric ratio. 2+ The compound was formulated into a precursor mixture according to the target stoichiometric ratio, so that the final material composition was NaBi. 0.89-x Yb 0.1 Er 0.01 Ca x (MoO4)2,; Mix and grind the raw materials thoroughly; The pretreated mixture is loaded into a sintering device for sintering and bonding. After sintering, the product is removed and crushed and finely ground to obtain the finished product.

[0012] Further preparation methods, including sintering, are performed with the following temperature control settings: Main firing temperature: 640-700 ℃; Insulation time: 8–16 h; Temperature program: The temperature rise rate is 1-10 °C / min or the temperature rise time is 2-10 h; Cooling procedure: After the main firing, cool down to room temperature using a program to reduce thermal stress (e.g., 5-100 ℃ / h or control the cooling time to 6-20 h).

[0013] Further preparation methods can provide Ca 2+ The compounds are CaCO3, CaO, or Ca(NO3)2.

[0014] 3. Beneficial effects Compared with existing known technologies, the technical solution provided by this invention has the following significant advantages: This invention provides a high-purity green luminescence and high optical thermometric sensitivity material regulated by non-equivalent ions for upconversion, and its preparation method. The material exhibits effective absorption in the near-infrared band, which is well-matched with the emission band of currently commercial near-infrared lasers, thus enabling it to be effectively excited to produce stable green upconversion emission. This is achieved by introducing non-equivalent ions (Ca). 2+ By regulating the cell environment, the proportion and color purity of green emission can be significantly improved, with the green emission color purity reaching 96.8%. Furthermore, a system based on Er³... + The relationship between the luminescence intensity of the thermally coupled energy level and temperature enables highly sensitive optical thermometry within the range of 300 K to 460 K, with a relative sensitivity of 1.282 %·K. -1 The absolute sensitivity is 1.793 K. -1 The material of this invention has significant practical application value in the fields of high-purity green light emission and non-contact optical temperature measurement. Attached Figure Description

[0015] Figure 1 NaBi as a specific embodiment 0.86 Yb 0.1 Er 0.01 Ca 0.03 XRD pattern of (MoO4)2 green luminescent material; Figure 2 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 Emission spectrum of (MoO4)2 green luminescent material; Figure 3 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 CIE chromaticity coordinate diagram of (MoO4)2 green luminescent material; Figure 4 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 Temperature-varying spectrum of (MoO4)2 green luminescent material; Figure 5 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 The relationship between the luminescence intensity ratio of (MoO4)2 green luminescent materials and temperature; Figure 6 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 Relative sensitivity curve of (MoO4)2 green luminescent material Figure 7 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 Absolute sensitivity curve of (MoO4)2 green luminescent material; Figure 8 For specific embodiments, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 The reliability of the thermometer during multiple heating-cooling cycles of (MoO4)2 in the range of 300 K-460 K was verified. Detailed Implementation

[0016] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0017] Example 1 The high-purity green luminescent and high optical temperature sensing sensitivity material and its preparation method in this embodiment include the following basic steps: Ingredients: Weigh high-purity raw materials Na2CO3, Bi2O3, MoO3, Yb2O3, Er2O3, and CaCO3 (or CaO, Ca(NO3)2, etc., which can provide Ca) according to the stoichiometric ratio. 2+ The precursor mixture was prepared according to the target stoichiometric ratio of the compound to make the final material composition NaBi 0.89-x Yb 0.1 Er 0.01 Ca x (MoO4)2, x = 0.01-0.10.

[0018] Pretreatment: Mix and grind the raw materials thoroughly (using an agate mortar and pestle for dry grinding or ball milling) to obtain a homogeneous mixture.

[0019] High-temperature solid-state sintering: The pretreated mixture is loaded into a sintering apparatus, such as a crucible, preferably a corundum crucible, and placed in a muffle furnace for a high-temperature solid-state reaction. The sintering process can be set according to the following preferred ranges: Main firing temperature: 640-700 ℃; Insulation time: 8–16 hours; Temperature rise program: Use a programmed temperature rise curve to reduce thermal shock (e.g., 1-10 ℃ / min or control the temperature rise time from room temperature to main firing temperature within 2–10 h). Cooling procedure: After the main firing, cool down to room temperature using a programmed curve to reduce thermal stress (e.g., 5-100 ℃ / h or control the cooling time to 6-20 h).

[0020] Post-processing: After sintering, the product is removed and crushed and finely ground to obtain upconversion phosphor material, namely high-purity green luminescent and high optical temperature sensitivity material; preferably, secondary grinding or secondary sintering is performed to further improve the uniformity of composition and crystallinity.

[0021] Example 2 The high-purity green luminescent and high optical temperature sensing sensitivity material and preparation method in this embodiment are basically the same as those in Embodiment 1, with the following differences or improvements: NaBi prepared by high temperature solid-state method 0.89-x Yb 0.1 Er 0.01 Ca x(MoO4)2 green luminescent material, in which, x =0.03; Na₂CO₃, Bi₂O₃, MoO₃, Yb₂O₃, Er₂O₃, and CaCO₃ were weighed and mixed according to stoichiometric ratios, wherein Yb₂O₃... 3+ Er 3+ The stoichiometric ratios were 10 at% and 1 at%, respectively, for Ca. 2+ Doping amount x Prepared at 0.03, its target chemical formula is NaBi. 0.89- x Yb 0.1 Er 0.01 Ca x (MoO4)2. Each portion of raw material was placed in an agate mortar and ground thoroughly to obtain a homogeneous mixture. The ground mixture was then placed in a corundum crucible and subjected to a high-temperature solid-state reaction in a muffle furnace: the temperature was increased from room temperature to approximately 660 °C (heating time approximately 6 h) using a programmed heating method, and held at 660 °C for 12 h to promote the complete solid-state reaction. Then, the temperature was cooled to room temperature (cooling time approximately 6 h). After removing the sintered product, it was finely ground again to obtain non-equivalent Ca ions. 2+ A sample of upconversion green phosphor with regulated emission.

[0022] The XRD characterization results of the prepared samples are attached. Figure 1 As shown, the diffraction peaks of all samples are consistent with the standard diffraction peaks of NaBi(MoO4)2, indicating that the samples have a tetragonal crystal structure, space group I41 / a, and no obvious impurity phases were observed.

[0023] The optical thermometric performance of the preferred sample (x=0.03) was evaluated. The variable-temperature upconversion emission spectrum of the sample tested in the temperature range of 300 K-460 K is attached. Figure 4 As shown, the intensities of the two green emission bands undergo reversible changes with increasing temperature. An FIR is constructed using the two green emission peaks (e.g., the integrated intensities at 530 nm and 550 nm), and their calibration curves versus temperature are established as shown in the attached figure. Figure 5 As shown. Based on the calibration relationship, the temperature sensitivity was calculated, and within the temperature range of 300 K–460 K, the sample's relative sensitivity reached a maximum of 1.282 %K. -1 The absolute sensitivity can reach up to 1.793%K. -1 As shown in the attached figures Figure 6 , Figure 7 As shown, this invention utilizes non-equivalent ions Ca... 2+ Regulation can significantly improve Er-based 3+Optical temperature sensitivity of thermally coupled energy levels. To verify the repeatability of temperature measurements of the material, FIR measurements were repeatedly performed on the sample under heating and cooling cycles, and temperature cycling was conducted. The results show that the calibration curve has good repeatability and stability (see appendix). Figure 8 ).

[0024] Example 3 The high-purity green luminescent and high optical temperature sensing sensitivity material and preparation method in this embodiment are basically the same as those in Embodiment 2, with the following differences or improvements: NaBi prepared by high temperature solid-state method 0.89-x Yb 0.1 Er 0.01 Ca x (MoO4)2 green luminescent material, in which, x The values ​​are 0.01 and 0.10, respectively; the process parameters for different material preparation methods are shown in Table 1: Table 1: Process parameters in the preparation methods of different high-purity green luminescent and high optical thermometric sensitivity materials

[0025] NaBi prepared in Examples 2 and 3 0.86 Yb 0.1 Er 0.01 Ca 0.03 (MoO4)2、NaBi 0.88 Yb 0.1 Er 0.01 Ca 0.01 (MoO4)2 and NaBi 0.79 Yb 0.1 Er 0.01 Ca 0.10 (MoO4)2 green luminescent material, after testing, NaBi 0.86 Yb 0.1 Er 0.01 Ca 0.03 (MoO4)2、NaBi 0.88 Yb 0.1 Er 0.01 Ca 0.01 (MoO4)2 and NaBi 0.79 Yb 0.1 Er 0.01 Ca 0.10 The diffraction peaks of all samples of (MoO4)2 were consistent with the standard diffraction peaks of NaBi(MoO4)2, indicating that all samples had a tetragonal crystal structure, space group I41 / a, and no obvious impurity phases were observed; with the increase of Ca... 2+ As the content increases, the characteristic diffraction peaks show a regular shift, indicating that Ca... 2+Doping causes a change in the cell parameters and successfully inserts the dopant into the cell. (See attached image) Figure 2 As shown, the sample was excited using a 980 nm near-infrared laser. The sample exhibited predominantly green upconversion emission in the visible light region, with the main emission peaks located near 530 nm and 550 nm, corresponding to Er... 3+ The relevant energy level transitions exhibit excellent absorption characteristics in the near-infrared band, making them compatible with currently available near-infrared chips and thus effectively excited. Comparison of different Ca... 2+ The emission intensity of the sample with Ca content indicates that when Ca... 2+ The green upconversion emission intensity of the sample reached its maximum at a doping concentration of 3 at%, indicating that Ca in this system... 2+ The preferred doping amount is 3 at%; when Ca² + As the concentration continues to increase, the emission intensity decreases, exhibiting a concentration quenching phenomenon. The mechanism is due to Ca... 2+ The introduction of Ca leads to a charge imbalance, and the system maintains electroneutrality by creating vacancies. 2+ When the concentration is greater than 3 at%, it will become a non-radiative center due to the generation of too many defects and charge traps, thus forming a structure-induced concentration quenching.

[0026] The green luminescent materials prepared in Examples 1, 2, and 3 exhibit the following mechanism for upconversion regulated by non-equivalent ions: Ca 2+ Replace Bi in the unit cell 3+ At the lattice sites, the valences of the two ions do not match, so vacancies are created to maintain electroneutrality. An appropriate number of vacancies reduces certain non-radiative relaxation channels, thereby enhancing Er. 3+ The radiation probability. When Ca 2+ When the concentration of Ca exceeds 3 at%, it becomes a non-radiative center due to the excessive formation of defects and charge traps, resulting in structural concentration quenching. Furthermore, because Ca... 2+ The ionic radius of (1 Å) is smaller than that of Bi. 3+ The ionic radius of (1.03 Å) causes lattice contraction, which in turn affects the optical luminescence and optical thermometry properties.

[0027] The CIE chromaticity coordinates of the sample were calculated based on the emission spectrum, and the chromaticity diagram is shown in the attached figure. Figure 3 As shown, the sample's emission color is concentrated in the green region, with the lowest green emission purity reaching 96.8%, indicating that the material of this invention possesses high-purity green upconversion luminescence properties. Therefore, the NaBi prepared in Examples 1-3... 0.89-x Yb 0.1 Er 0.01 Ca x (MoO4)2( x=0.03) upconversion phosphor combines high-purity green light emission with high-sensitivity optical temperature measurement performance. Its performance advantages include: non-contact, fast response (μs level), resistance to electromagnetic interference, and high spatial resolution (μm level). It is suitable for temperature measurement in closed, rotating, and strong electromagnetic environments, such as phase transition temperature measurement of superconducting materials and temperature monitoring of deep space probe components. It is resistant to low temperatures (liquid helium temperature range) and radiation, and has excellent stability. It has important and wide application value in the fields of high-purity green light emission and non-contact optical temperature measurement.

[0028] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention. The actual structure and manufacturing steps are not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A high-purity green luminescent material with high optical temperature sensing sensitivity, characterized in that: Its general chemical formula is NaBi 0.89- x Yb 0.1 Er 0.01 Ca x (MoO4)2, where, x = 0.01-0.

10.

2. The high-purity green luminescent and high optical temperature sensing sensitivity material according to claim 1, characterized in that, It belongs to the tetragonal crystal system and has the space group I41 / a.

3. The high-purity green luminescent and high optical temperature sensing sensitivity material according to claim 2, characterized in that, NaBi 0.89 Yb 0.1 Er 0.01 Using the (MoO4)2 complex as a matrix, the Ca ions are regulated by the unit cell. 2+ The doping modulates the cell structure.

4. The high-purity green luminescent and high optical temperature sensing sensitivity material according to claim 3, characterized in that, Cell-regulated ion Ca 2+ The doping concentration is 3 at.

5. The high-purity green luminescent and high optical temperature sensing sensitivity material according to claim 3, characterized in that, Its green emission purity is the lowest at 96.0%; its optical thermometric relative sensitivity is the highest at 1.282%K. -1 The highest absolute sensitivity for optical temperature measurement is 1.793%K. -1 .

6. The high-purity green luminescent and high optical temperature sensing sensitivity material according to claim 5, characterized in that, The temperature range for both the relative and absolute sensitivity of optical thermometry is 300 K-460 K.

7. A method for preparing a high-purity green luminescent and high optical thermometric sensitivity material according to any one of claims 1-6, characterized in that, Includes the following steps: Weigh out the high-purity raw materials Na2CO3, Bi2O3, MoO3, Yb2O3, Er2O3, and other materials that can provide Ca according to the stoichiometric ratio. 2+ The compound was formulated into a precursor mixture according to the target stoichiometric ratio, so that the final material composition was NaBi. 0.89-x Yb 0.1 Er 0.01 Ca x (MoO4)2,; The raw materials are thoroughly mixed and ground; The pretreated mixture is loaded into a sintering device for sintering and bonding. After sintering, the product is removed and crushed and finely ground to obtain the finished product.

8. The preparation method according to claim 7, characterized in that: The sintering process is controlled by the following temperature settings: Main firing temperature: 640-700 ℃; Insulation time: 8–16 h; Temperature rise program: The temperature rise time is 2–10 h.

9. The preparation method according to claim 7, characterized in that: Can provide Ca 2+ The compounds are CaCO3, CaO, or Ca(NO3)2.

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