Technology for defect regulation and control of ZnS fluorescent material emission spectrum

Abstract

The invention discloses a technology for regulating and controlling the emission spectrum of a ZnS fluorescent material by defects, which comprises the following steps of: weighing raw materials of 3Zn (OH) 2.2 ZnCO3, CuCl2. 2H2O, S powder and Al (NO3) 3.9 H2O according to a stoichiometric ratio, adding a proper amount of sintering aid NH4Cl, grinding until the materials are uniformly mixed, and calcining for 0.5-2 hours at the temperature of 900-1150 DEG C by utilizing a sulfur fluxing method to obtain ZnS: Cu < + > and Al < 3 + > fluorescent material powder with excellent luminescent property. According to the invention, the defects of the ZnS fluorescent material are regulated and controlled by assisting temperature control through a fluxing agent, so that emission control of blue light and green light is realized.

Description

Technical Field

[0001] The present invention relates to a technology for defect-modulating the emission spectrum of ZnS fluorescent materials. The technology adopts a sulfur fluxing method and can prepare ZnS:Cu nanostructured carbon nanotubes with excellent performance in one step to meet the luminescence requirements in different scenarios by regulating defects. + ,Al 3+ Fluorescent material, ZnS:Cu + ,Al 3+ The emission spectrum peak of the fluorescent material can be changed according to demand. This technology belongs to the field of optoelectronic functional materials. Background Art

[0002] In image intensifiers, cathode ray tube (CRT) displays and X-ray detection technologies, ZnS:Cu + ,Al 3+ The phosphor screen made of luminescent materials is a key device for image intensifiers, cathode ray tubes, and X-ray detectors, and is an important component for achieving cathode ray luminescence and X-ray imaging. + ,Al 3+ Compared with other luminescent materials, it has the advantages of high luminous efficiency, high resolution after application in fluorescent screens, and relatively superior comprehensive performance. Therefore, ZnS:Cu with excellent luminous performance and multi-scenario application is developed. + ,Al 3+ Fluorescent materials, used in image intensifiers, cathode ray tube (CRT) displays, X-ray detection, etc., have significant research value and important research significance.

[0003] As a typical direct wide bandgap II-VI compound semiconductor, ZnS has excellent luminescence performance due to its high bandgap width of 3.67eV at room temperature, and has always been a hot spot in luminescence research. ZnS doping refers to the use of ZnS as a matrix to introduce other impurity elements to generate additional energy levels in the bandgap of ZnS, thereby forming new electron and hole defect energy levels. By introducing different types of elements into the ZnS lattice through doping, the bandgap energy of electron transition can be improved, resulting in corresponding new luminescence properties. ZnS:Cu + ,Al 3+ The fluorescent material is a ZnS-based fluorescent material doped with metal ions. + and Al 3+ Ions are introduced into the ZnS matrix to change the energy band structure of ZnS, and luminescence is achieved under the excitation of light, electricity, and X-rays. + ,Al 3+ The main process methods include high temperature solid phase method, hydrothermal method, microemulsion method, solvent thermal method, chemical synthesis method and sol-gel method. In 1996, Qi et al. synthesized submicron-sized ZnS:Cu by chemical solution method.+ ,Al 3+ When the acceleration voltage is 1KV, the brightness of the electron-excited luminescent material is 94% of that of commercial luminescent materials. + ,Cl - and ZnS:Cu + ,Al 3+ The electroluminescent properties of the luminescent powder were studied, and it was pointed out that the emission spectrum of the luminescent powder was affected by Cu + concentration, and pointed out that ZnS:Cu + ,Cl - and ZnS:Cu + ,Al 3+ In 2009, Xin Mei et al. directly synthesized high-luminescence intensity ZnS:Cu by hydrothermal method. + ,Al 3+ Nano-phosphors, it was found that the luminescence intensity is determined by the surface state of the nanomaterials, and the molar ratio of the doped activator also affects the emission spectrum. In 2023, Li Xin et al. prepared ZnS:Cu by high-temperature solid-phase reaction in a reducing atmosphere. + ,Al 3+ phosphor, designed a Cu + and Al 3+ Co-doped ZnS scintillator (ZnS:Cu + ,Al 3+ ) for X-ray detection. However, the current blue and green ZnS:Cu + ,Al 3+ Fluorescent materials are difficult to control, so a method to control the ZnS:Cu + ,Al 3+ The technology of blue and green light emission from fluorescent materials. Summary of the invention

[0004] In order to target different scenarios, ZnS:Cu + ,Al 3+ The invention provides a technology for defect-controlled emission spectrum of ZnS fluorescent materials for the application of blue and green luminescence of fluorescent materials.

[0005] The present invention is in ZnS:Cu + ,Al 3+ In the preparation process of fluorescent materials, 3Zn(OH) 2 ·2ZnCO 3 , CuCl 2 ·2H 2 O, S powder, Al(NO 3 ) 3 9H 2O as raw material, using sulfur flux method, through reasonable design and regulation of synthesis process and flux NH 4 Cl realizes defect luminescence regulation.

[0006] The core of the present invention is that it can enhance the formation of defects by adjusting the sintering temperature and the flux combination, so that different defect energy levels are generated. The principle of the present invention is that the ZnS-based material belongs to the donor-acceptor type doping and has two crystal structures. By adjusting the sintering temperature, in the flux NH 4 With the help of Cl, it forms different crystal structures, thus obtaining different defect energy levels and different luminescence properties. In the sphalerite structure, the luminescence is formed by the substitutional impurity Cu forming the luminescence center, the Al (donor) energy level captures electrons and the Cu (acceptor) t 2 Energy level capture vacancy recombination luminescence. In wurtzite, a substitutional Cu + and interstitial Cu composed of Cu blue light emitting centers and Al 3+ (Donor) and V Zn The radiation transition generated by the defect energy level between the (acceptor) emits blue light. + ,Al 3+ The blue and green light emissions of fluorescent materials are used in different scenarios.

[0007] In the process of raw material selection, the present invention uses S powder as the sulfur source of sulfide, 3Zn(OH) 2 ·2ZnCO 3 Zn for the synthesis of ZnS 2+ Source, via flux NH 4 Cl assists in reducing the temperature required for the reaction while effectively controlling the phase, promoting the growth of grains, reducing the impurities in the phase structure, and promoting the metal ion (Cu + and Al 3+ ) is doped into the matrix lattice to ensure the formation of defects. Calcination at 900-1150°C for 0.5-2h produces ZnS:Cu with excellent luminescence performance. + ,Al 3 + Fluorescent material. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The ZnS:Cu + ,Al 3+ XRD patterns of fluorescent material samples.

[0009] Figure 2 The ZnS:Cu + ,Al 3+ Photoluminescence blue light excitation spectrum of fluorescent material samples.

[0010] Figure 3 The ZnS:Cu + ,Al 3+ Photoluminescence blue light emission spectrum of fluorescent material samples.

[0011] Figure 4 The ZnS:Cu + ,Al 3+ Blue light emission spectrum of fluorescent material sample under cathode ray excitation.

[0012] Figure 5 The ZnS:Cu + ,Al 3+ Photoluminescence green light excitation spectrum of fluorescent material samples.

[0013] Figure 6 The ZnS:Cu + ,Al 3+ Photoluminescence green emission spectrum of fluorescent material samples.

[0014] Figure 7 The ZnS:Cu + ,Al 3+ Green light emission spectrum of fluorescent material sample under cathode ray excitation. DETAILED DESCRIPTION

[0015] The ZnS:Cu with blue-green light emission in the present invention + ,Al 3+ The specific process of fluorescent materials is described in detail as follows:

[0016] (1) Using 3Zn(OH) 2 ·2ZnCO 3 (AR), CuCl 2 ·2H 2 O(AR), S powder(AR), Al(NO 3 ) 3 9H 2 O(AR) as raw material, NH 4 Cl(AR) is a flux. According to ZnS:xCu + ,yAl 3+ The amount of each raw material is calculated based on the stoichiometric ratio, where x is Cu + The doping amount of ions, x is 0.02at%, y is Al 3+ The doping amount of the ion, y, is 0.01 at%, and the content of the flux is 8 to 12 wt% of the product.

[0017] (2) According to the preparation of 5g sample, use a precision electronic balance to weigh the corresponding amount of 3Zn(OH) 2 ·2ZnCO 3 , S powder, CuCl 2 ·2H 2 O, Al(NO 3 ) 3 9H 2 O, NH 4 Cl raw materials, put the weighed raw materials into an agate mortar, grind for 20 to 60 minutes to mix the raw materials evenly, and put them into a 25ml alumina crucible;

[0018] (3) Select a 100ml alumina crucible, fill it with excess C powder, insert the 25ml crucible containing the raw materials into the 100ml crucible, and send it into the box-type resistance furnace;

[0019] (4) Start sintering, wherein the heating rate does not exceed 5°C / min, the sintering temperature is set to 900-1150°C, and the holding time is 0.5-2h;

[0020] (5) After sintering, the furnace is cooled down, and the sample is taken out and ground to obtain ZnS:Cu with excellent luminescence performance. + ,Al 3+ Fluorescent material samples.

[0021] Figure 1 The prepared ZnS:Cu + ,Al 3+ The XRD spectrum of the fluorescent material sample is consistent with the diffraction peaks of the standard cards PDF#05-0566 and PDF#36-1450, indicating that the ZnS phase and Cu + and Al 3+ It successfully entered into the ZnS matrix, and had sharp diffraction peaks, high intensity and good crystallinity.

[0022] Example 1: Blue ZnS:Cu + ,Al 3+ Fluorescent Materials

[0023] (1) Using 3Zn(OH) 2 ·2ZnCO 3 (AR), CuCl 2 ·2H 2 O(AR), S powder(AR), Al(NO 3 ) 3 9H 2 O(AR) as raw material, NH 4 Cl(AR) is a flux. According to ZnS:xCu + ,yAl3+ The amount of each raw material is calculated based on the stoichiometric ratio, where x is Cu + The doping amount of ions, x is 0.02at%, y is Al 3+ The doping amount of ions, y, is 0.01at%, and the NH 4 The Cl content was 8 wt% of the product.

[0024] (2) According to the preparation of 5g sample, use a precision electronic balance to weigh the corresponding amount of 3Zn(OH) 2 ·2ZnCO 3 , S powder, CuCl 2 ·2H 2 O, Al(NO 3 ) 3 9H 2 O, NH 4 Cl raw materials, put the weighed raw materials into an agate mortar, grind for 20 to 60 minutes to mix the raw materials evenly, and put them into a 25ml alumina crucible;

[0025] (3) Select a 100ml alumina crucible, fill it with excess C powder, insert the 25ml crucible containing the raw materials into the 100ml crucible, and send it into the box-type resistance furnace;

[0026] (4) Start sintering, wherein the heating rate does not exceed 5°C / min, the sintering temperature is set to 1100°C, and the holding time is 0.5 to 2h;

[0027] (5) After sintering, the furnace is cooled down, and the sample is taken out and ground to obtain ZnS:Cu with excellent luminescence performance. + ,Al 3+ Blue fluorescent material sample.

[0028] Figure 2 The prepared ZnS:Cu + ,Al 3+ The blue light emission excitation spectrum of the fluorescent material sample is a broadband spectrum with multiple defect energy levels. The spectrum can be controlled according to the defect energy levels. When the peak is at 340nm, it can have bright blue light emission under ultraviolet light excitation. Figure 3 The prepared ZnS:Cu + ,Al 3+ The blue light emission spectrum of the fluorescent material sample. The emission spectrum of the sample is a broadband spectrum with a peak at 446nm. Figure 4 The prepared ZnS:Cu + ,Al 3+ The emission spectrum of the fluorescent material sample under cathode ray excitation is a broadband spectrum with a peak at 450nm.

[0029] Example 2: Green ZnS:Cu + ,Al 3+ Fluorescent Materials

[0030] (1) Using 3Zn(OH) 2 ·2ZnCO 3 (AR), CuCl 2 ·2H 2 O(AR), S powder(AR), Al(NO 3 ) 3 9H 2 O(AR) as raw material, NH 4 Cl(AR) is a flux. According to ZnS:xCu + ,yAl 3+ The amount of each raw material is calculated based on the stoichiometric ratio, where x is Cu + The doping amount of ions, x is 0.02at%, y is Al 3+ The doping amount of ions, y, is 0.01at%. 4 The Cl content was 12 wt% of the product.

[0031] (2) According to the preparation of 5g sample, use a precision electronic balance to weigh the corresponding amount of 3Zn(OH) 2 ·2ZnCO 3 , S powder, CuCl 2 ·2H 2 O, Al(NO 3 ) 3 9H 2 O, NH 4 Cl raw materials, put the weighed raw materials into an agate mortar, grind for 20 to 60 minutes to mix the raw materials evenly, and put them into a 25ml alumina crucible;

[0032] (3) Select a 100ml alumina crucible, fill it with excess C powder, insert the 25ml crucible containing the raw materials into the 100ml crucible, and send it into the box-type resistance furnace;

[0033] (4) Start sintering, wherein the heating rate does not exceed 5°C / min, the sintering temperature is set to 950°C, and the holding time is 0.5 to 2h;

[0034] (5) After sintering, the furnace is cooled down, and the sample is taken out and ground to obtain ZnS:Cu with excellent luminescence performance. + ,Al 3+ Green fluorescent material sample.

[0035] Figure 5The prepared ZnS:Cu + ,Al 3+ The green light emission excitation spectrum of the fluorescent material sample is a broadband spectrum with multiple defect energy levels. The spectrum can be controlled according to the defect energy levels. When the peak is at 370nm, it can have bright green light emission under ultraviolet light excitation. Figure 6 The prepared ZnS:Cu + ,Al 3+ Green light emission spectrum of the fluorescent material sample. The emission spectrum of the sample is a broadband spectrum with a peak at 521nm. Figure 7 The prepared ZnS:Cu + ,Al 3+ Green light emission spectrum of the fluorescent material sample under cathode ray excitation. The emission spectrum of the sample is a broadband spectrum with a peak at 528nm.

Claims

1. A technology for defect-controlled emission spectrum of ZnS fluorescent materials, which uses 3Zn(OH)2·2ZnCO3, CuCl2·2H2O, S powder and Al(NO3)3·9H2O as raw materials, uses NH4Cl sintering aid, combines temperature adjustment, controls the crystal structure of fluorescent materials, achieves defect control, and obtains blue and green light emitting ZnS:Cu + ,Al 3+ Fluorescent material, the fluorescent material adopts sulfur fluxing method, and calcined for 0.5 to 2 hours in the reducing atmosphere provided by C powder at 900℃ to 1150℃ to obtain ZnS:Cu with excellent luminescence performance + ,Al 3+ Fluorescent material.

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