BLUE FLUORESCENT POWDER FOR THREE PRIMARY COLOR WARM WHITE LIGHT LED AND PREPARATION METHOD THEREFOR

Abstract

The present disclosure discloses a blue fluorescent powder for a three primary color warm white LED and a preparation method thereof. SrCO.sub.3, NH.sub.4Cl, H.sub.3BO.sub.3, Eu.sub.2O.sub.3, and NH.sub.4H.sub.2PO.sub.4 function as raw materials to obtain a chemical formula of a blue fluorescent powder Sr.sub.(2-x)Eu.sub.x(BO.sub.3).sub.y(PO.sub.4).sub.(1-y)Cl in a reducing atmosphere by a solid-state sintering method, wherein 0.001x0.1 and 0.001y0.5. The blue fluorescent powder is mixed with CaAlSiN.sub.3:Eu.sup.2+ red fluorescent powder and (SrBa).sub.2SiO.sub.4:Eu.sup.2+ green fluorescent powder at a certain proportion to emit warm white light with a light efficiency and a color rendering index under a violet light excitation. An application prospect is wide.

Claims

1. A blue fluorescent powder for a three primary color warm white light-emitting diode (LED), wherein a chemical formula of the blue fluorescent powder is Sr.sub.(2-x)Eu.sub.x (BO.sub.3).sub.y(PO.sub.4).sub.(1-y)Cl, wherein 0.001x0.1 and 0.001y0.5.

2. The blue fluorescent powder for the three primary color warm white LED according to claim 1, wherein the chemical formula of the blue fluorescent powder is Sr.sub.1.95Eu.sub.0.05(BO.sub.3).sub.0.25(PO.sub.4).sub.0.75Cl.

3. The blue fluorescent powder for the three primary color warm white LED according to claim 1, wherein the chemical formula of the blue fluorescent powder is Sr.sub.1.99Eu.sub.0.01(BO.sub.3).sub.0.25(PO.sub.4).sub.0.75Cl.

4. A method for preparing a blue fluorescent powder for a three primary color warm white LED comprising: (a) weighing raw materials SrCO.sub.3, NH.sub.4Cl, H.sub.3BO.sub.3, Eu.sub.2O.sub.3, and NH.sub.4H.sub.2PO.sub.4 according to a molar ratio of each element of a chemical formula with Sr.sub.(2-x)Eu.sub.x(BO.sub.3).sub.y(PO.sub.4).sub.(1-y)Cl of the blue fluorescent powder, mixing, and grinding to obtain a mixture, wherein in the chemical formula, 0.001x0.1 and 0.001y0.5; (b) placing the mixture in a reducing atmosphere, heating up to 900-1150 C., and roasting for 4-5 hours to obtain a sintered body; and (c) cooling the sintered body to room temperature and grinding to obtain the blue fluorescent powder for the three primary color warm white LED.

5. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 4, wherein in step (a), in the chemical formula, x=0.05 and y=0.25.

6. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 4, wherein in step (a), a time of the grinding is 10-20 minutes.

7. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 4, wherein in step (b), a heating rate is 3-7 C./min.

8. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 4, wherein in step (b), the reducing atmosphere is a reducing atmosphere formed by mixed gas of H.sub.2 and N.sub.2 or is carbon powder and the mixture is embedded in the carbon powder.

9. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 4, wherein in step (b) roasting for 4-5 hours comprises roasting for 5 hours.

10. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 5, wherein in step (b), roasting for 4-5 hours comprises roasting for 5 hours.

11. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 6, wherein in step (b), roasting for 4-5 hours comprises roasting for 5 hours.

12. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 7, wherein in step (b), roasting for 4-5 hours comprises roasting for 5 hours.

13. The method for preparing the blue fluorescent powder for the three primary color warm white LED according to claim 8, wherein in step (b), roasting for 4-5 hours comprises roasting for 5 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is X-ray diffraction spectra (XRD) of a blue fluorescent powder prepared in Embodiment 1 and Embodiment 2.

[0022] FIG. 2 is an excitation spectrum and an emission spectrum of the blue fluorescent powder prepared in Embodiment 1, wherein an excitation wavelength ex=395 nm and an emission wavelength em=446 nm.

[0023] FIG. 3 is an emission spectrum of a three primary color warm white fluorescent powder prepared in Embodiment 1, wherein an excitation wavelength is 395 nm.

[0024] FIG. 4 is a luminescence spectrum and a color coordinate graph of a three primary color warm white light-emitting diode (LED) prepared in Embodiment 1 when under a near ultraviolet light excitation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present disclosure will be further described below with the accompanying embodiments. However, the present disclosure is not limited to the embodiments in any way. Unless otherwise specified, reagents, methods, equipment of the present disclosure are conventional reagents, methods, and equipment of the technical art. However, the present disclosure is not limited in any way.

Embodiment 1

[0026] Weighing 1.406 g of strontium carbonate (SrCO.sub.3), 0.268 g of anhydrous ammonium chloride (NH.sub.4Cl), 0.062 g of boric acid (H.sub.3BO.sub.3), 0.088 g of europium trioxide (Eu.sub.2O.sub.3), and 0.371 g of ammonium dihydrogen phosphate (NH.sub.4H.sub.2PO.sub.4), putting into an agate mortar, grinding for 30 minutes, and mixing evenly. Roasting the grinded powder in a reducing atmosphere, heating to 1000 C. at a heating rate of 5 C./min, sintering (using a solid-phase sintering method) at the temperature for 6 hours, and then naturally cooling to room temperature (e.g., 20 C.-25 C.). Taking the sample out and grinding to obtain a fluorescent powder with a chemical formula of Sr.sub.1.95Eu.sub.0.05(BO.sub.3).sub.0.25(PO.sub.4).sub.0.75Cl. An X-ray diffraction spectrum (XRD) of the fluorescent powder is shown in FIG. 1.

[0027] The raw materials, SrCO.sub.3 Analytical Reagent (A.R.), NH.sub.4Cl (A.R.), H.sub.3BO.sub.3 (A.R.), Eu.sub.2O.sub.3 (99.99 wt %), and NH.sub.4H.sub.2PO.sub.4 (A.R.), of the Embodiment of the present disclosure are all commercially available products.

[0028] Mixing the prepared Sr.sub.1.95Eu.sub.0.05(BO.sub.3).sub.0.25(PO.sub.4).sub.0.75Cl fluorescent powder with CaAlSiN.sub.3:Eu.sup.2+ red fluorescent powder and (SrBa).sub.2SiO.sub.4:Eu.sup.2+ green fluorescent powder at a certain proportion under violet light excitation (near ultraviolet light) and coating on an InGaN LED chip with an emission wavelength of 395 nm and an operating current of 350 mA to emit warm white light with a color temperature of 3153K. An optical performance of the luminescent material prepared in the embodiment was tested. When the color rendering index is more than 90, the light efficiency is up to 86.7 lm/W.

[0029] The results are shown in FIGS. 2 to 4.

Embodiment 2

[0030] Embodiment 2 is basically the same as Embodiment 1 except that a chemical formula of a prepared fluorescent powder is different. An X-ray diffraction spectrum (XRD) is shown in FIG. 1.

[0031] 1.465 g of strontium carbonate (SrCO.sub.3), 0.268 g of anhydrous ammonium chloride (NH.sub.4Cl), 0.062 g of boric acid (H.sub.3BO.sub.3), 0.018 g of europium trioxide (Eu.sub.2O.sub.3), and 0.371 g of ammonium dihydrogen phosphate (NH.sub.4H.sub.2PO.sub.4) was weighed, was put into an agate mortar, and then was ground for 30 minutes to mix evenly. The ground powder was roasted in a reducing atmosphere and was heated to 1000 C. at a heating rate of 5 C./min, was sintered at this temperature for 6 hours, and then was naturally cooled to room temperature (e.g., 20 C.25 C.). The sample was taken out and was ground to obtain a fluorescent powder with the chemical formula Sr.sub.1.99Eu.sub.0.01(BO.sub.3).sub.0.25(PO.sub.4).sub.0.75Cl.

[0032] The aforementioned embodiments are preferred embodiments. However, embodiments of the present disclosure are not limited to the aforementioned embodiments. Any modifications, variations, combinations, and simplifications without departing from the spirit or scope of the present disclosure are all equivalents to come within the scope of the appended claims and their equivalents.