Rapid preparation method for MSi2O2N2:Eu<2+> phosphor

Abstract

The invention relates to a rapid preparation method for a MSi2O2N2:Eu<2+> phosphor. The rapid preparation method comprise the following steps of (1) weighing raw materials of silicon oxide, silicon nitride, alkaline earth oxide and europium oxide according to a molar ratio and in terms of the chemical formula M1-xSi2O2N2:Eux<2+>, then mixing the raw materials uniformly, and obtaining uniformly mixed raw material mixed powder; (2) putting the raw material mixed powder into a graphite die, directly applying a strong current to the upper and lower ends of the graphite die and heating to a temperature in a range from 1400 DEG C to 1550 DEG C in a protective atmosphere, maintaining the temperature for 0-20 min and cooling naturally, and obtaining the MSi2O2N2:Eu<2+> phosphor. The rapid preparation method is advantaged by fast heating rate, short holding time, and high conversion efficiency of phosphor synthesis, the synthetic phosphor need not be broken into pieces, the synthetic MSi2O2N2:Eu<2+> phosphor has a wide excitation wavelength range, has high emitted light intensity, and can be effectively excited by ultraviolet and blue light LED chips.

Description

technical field [0001] The invention relates to an inorganic luminescent material, in particular to an MSi 2 o 2 N 2 :Eu 2+ Rapid preparation method of phosphor powder. Background technique [0002] Light-emitting diode (LED) lighting has the advantages of high energy saving, long life, multiple changes, and environmental protection. Compared with traditional light sources, LED lighting can save more than 80% energy, which is a major step forward in energy-saving and environmental protection technology. At present, the commonly used white light realization method of LED is InGaN chip blue light excitation YAG: Ce 3+ It emits yellow light and recombines it with blue light to form white light, but this method is due to the YAG:Ce 3+ The excitation band is narrow, and the emission spectrum lacks red light components, so the color rendering index is not high, and it is difficult to exceed 85. The white light composed of three colors of red, green and blue can easily achie...

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Problems solved by technology

[0005] microwave method such as Chia-Hao Hsu et al. ("Microwave-hydrothermally synthesized (Sr1-x-yCexTby)Si2O2-δN2+μphosphors: efficient energy transfer, structural refinement and photoluminescence properties” J. Mater. Chem., 2011, 21, 2932–2939) Dissolve strontium nitrite, cerium nitrite, and terbium oxide in dilute nitric acid as raw materials, and then press Si4+ Add Si(OC2H5)4 as the Si source at a ratio of 2:1 to metal ions, add alcohol and stir, then microwave The precursor was formed by liquid treatment (2450 MHz, 500 W, 160 °C, 20 min), and finally the target product was obtained by using the traditional high-temperature synthesis method at 1350 °C for 4 h. Although this method can reduce the synthesis temperature to 1350 °C, the nitrous acid Strontium and cerium nitrite chemical raw materials are highly toxic and costly to store

[0006] gas phase reduction nitriding method patent such as: CN101698799A (porous spherical CaSi2O2N2 :Eu2+ phosphor preparation method), first dissolve calcium chloride, europium chloride and polyethylene glycol in water to form solution A; mix sodium carbonate, polyethylene glycol Glycol 6000 and sodium lauryl sulfate are dissolved in water to form solution B; pour solution A into solution B, stir and let it stand, wash with water and dry; take (Eu, Ca)CO3Disperse in water, add Na2SiO3 solution, adjust the pH value to 7-8, stir, wash with water, dry; in NH3 sub>Under airflow, heat up to 1250-1400°C, keep warm and cool down to room temperature to get Ca1-xSi2O2N2:Eux2+, in this method, the cost of strontium nitride and rare earth ion nitride is high; and the process is complicated, and it is easy to introduce sodium ion and Sulfate impurities

[0007]The traditional solid-phase synthesis method commonly used at present, such as: CN101525536 (a CaSi2O2N 2: Eu2+, Y3+ phosphor preparation method), SiO2, Si3N4, CaCO3, Eu2O3, Y 2O3 After mixing in proportion, in the tube furnace, control the nitrogen flow rate to 100-300ml / min, first raise the temperature to 800°C at a rate of 2-4°C / min, Insulate for 0.5-1h; then raise the temperature to 1350-1500°C at a rate of 1-3°C / min, and hold for 6-8h; this method is simple and suitable for mass production, but the traditional solid-phase synthesis method takes a long time to hold and the utilization rate of raw materials is low , the prepared luminescent material particles are relatively coarse, and the surface structure of the particles will be destroyed after crushing, reducing the luminous intensity and causing a large light attenuation

At the same time, in the solid state reaction method, during the dissolution-precipitation process of Si3N4 at a lower temperature in the early stage of the reaction, it is easy to precipitate stable high melting point oxygen-enriched The nitrogen oxide impurities in the phase are difficult to eliminate after a long time of incubation in the later stage of the reaction; therefore, it is difficult to directly synthesize Ba1-xSi2O2 by solid-phase synthesis N2:Eux2+ phosphor, Bong-Goo Yun et al. ["Preparation and Luminescence Properties of Single- Phase BaSi2O2N2:Eu2+, a Bluish-Green Phosphor for White Light-Emitting Diodes” Journal of The Electrochemical Society, 157(10)J364-J370(2010)] Using a two-step solid-phase synthesis method, first synthesize Ba2-2xSiO4: Eu2x2+, and then synthesize the target product with Si3N4 at high temperature, although this method It is possible to synthesize relatively pure fluorescent powder and improve its fluorescent performance, but the two-step solid-phase method not only increases the difficulty of the process, further prolongs the holding time, but also reduces the energy utilization rate

[0008] spark plasma sintering method such as Kee-Sun Sohn et al. ["Luminescence of Sr2SiO4??x N2x / 3:Eu2+ Phosphors Prepared by Spark Plasma Sintering”Journal of The Electrochemical Society , 155 (2) J58-J61(2008)] Apply an axial pressure of 16 MPa to the powder, and raise the temperature to 1100-1400°C for 5-10min at a heating rate of 100-230°C / min. The temperature field of this method Uniform, but the powder needs to be sintered into a block under pressure; although Kee-Sun Sohn et al., when designing the synthesis process, try to reduce the synthesis temperature to avoid the generation of a liquid phase, which causes the block to sinter under the action of axial pressure; However, under the action of axial pressure, the powder will still sinter into agglomerates, so the crystal lattice of the phosphor will be severely damaged during the process of being broken into phosphor powder, which will significantly reduce the fluorescence intensity of the phosphor, reduce the quantum efficiency, and reduce the optical efficiency. and in this study, the phases shown in the XRD pattern have not been assigned exactly, and the obtained product is not a single phase, but a mixture phase of at least two or more intermediate products

[0009]From the current research, MSi2O2N2:Eu2+ (M=Ca, Sr, Ba) phosphors have great application prospects in the field of high-power white light LEDs, but the method of synthesizing precursors first by chemical methods and then high-temperature synthesis is complicated and easy to introduce Impurities and low efficiency; the high-temperature solid-phase method relies on radiation heat transfer, and the properties of the synthesized phosphor are not uniform, and it is easy to precipitate an oxygen-rich phase that is difficult to eliminate during the slow heating process; the existing discharge plasma synthesis method has a fast heating rate and a uniform temperature field, but The powder is sintered into a block, which needs to be crushed and ground into powder by force, thereby destroying the phosphor lattice and reducing the luminous efficiency of the phosphor, and in the synthesis process, in order to control the formation of the liquid phase as much as possible, the product phase is impure

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