Phosphor and manufacturing method of the same, and light emitting device using the phosphor

• US 7,445,730 B2
• Filed: 09/06/2005
• Issued: 11/04/2008
• Est. Priority Date: 03/31/2005
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Dowa Electronics Materials Co. Ltd. (DOWA Holdings Company Limited)
• Inventors: Nagatomi, Akira, Sakane, Kenji
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US11/218,504
• Publication Number:
  US 20060220047A1
• Time in Patent Office: 1,155 Days
• Field of Search: 252/301.4 F, 313/503, 257/98
• US Class Current: 252/301.40F
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/502 Wavelength conversion materials

Abstract

To provide a phosphor having a broad emission spectrum in a range of blue color (peak wavelength from 400 nm to 500 nm), having a broad and flat excitation band in the range of near ultraviolet/ultraviolet, and having excellent emission efficiency and emission intensity/luminance. The phosphor is expressed by a general composition formula MmAaBbOoNn:Z (where element M is at least one or more kind of element having bivalent valency, element A is at least one or more kind of element having tervalent valency, element B is at least one or more kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is at least one or more kind of element acting as an activator.), satisfying 5.0<(a+b)/m<9.0, 0≦a/m≦2.0, 0≦o<n, n=2/3m+a+4/3b−2/3o, and having an emission spectrum with a maximum peak wavelength from 400 nm to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.

Claims

1. A phosphor, which is given as a general composition formula expressed by MmAaDbOoNn:

Z, (where element M is at least one kind of element having bivalent valency, element A is at least one kind of element having tervalent valency, element D is at least one kind of element having tetravalent valency, O is oxygen, N is nitrogen, and element Z is at least one kind of element acting as an activator), satisfying 6.0≦

(a+b)/m≦

8.0, 0.0≦

a/m≦

2.0, 0≦

o<

n, n=2/3m+a+4/3b−

2/30, 4.0≦

b/m≦

8.0, 0<

o/m≦

3.0, and having an emission spectrum with a maximum peak wavelength from 400 nm to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.

2. The phosphor according to claim 1, which is given as the composition formula expressed by a=x×

m, b=(6−

x)×

m, o=(1+x)×

m, and n=(8−

x)×

m, when satisfying 0≦

x≦

2 in the wavelength range from 400 nm to 500 nm.

3. The phosphor according to claim 1, wherein under an excitation of a monochromatic light in the wavelength range from 350 nm to 430 nm, satisfying P_min/P_max×

100≧

30, is obtained, when the maximum emission intensity of the emission spectrum is defined as P_max, and the minimum emission intensity of the emission spectrum is defined as P_min.

4. The phosphor according to claim 1, wherein the element M is at least one kind of element selected from a group consisting of Mg, Ca, Sr, Ba, Zn, and rare earth elements having bivalent valency, the element A is at least one kind of element selected from a group consisting of Al, Ga, In, Tl, Y, Sc, P, As, Sb, Bi, the element D is at least one kind of element selected from a group consisting of Si, Ge, Sn, Ti, Hf, Mo, W, Cr, Pb, and Zr, and the element Z is at least one kind of element selected from rare earth elements and transitional metal elements.

5. The phosphor according to claim 1, wherein the element M is at least one kind of element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn, the element A is at least one kind of element selected from the group consisting of Al, Ga, and In, the element D is Si and/or Ge, and the element Z is at least one kind of element selected from the group consisting of Eu, Ce, Pr, Tb, Yb, and Mn.

6. The phosphor according to claim 1, wherein the element M is Sr, the element A is Al, the element D is Si, and the element Z is Eu.

7. The phosphor according to claim 1, wherein when the general formula is expressed by MmAaDbOoNn:

Zz, the value of z/(m+z), which is a molar ratio of the element M to the element Z, is not less than 0.0001 and not more than 0.5.

8. The phosphor according to claim 1, containing Sr of 16.0 to 25.0 wt %, Al of 2.0 to 9.0 wt %, O of 0.5 to 11.5 wt %, N of 23.0 to 32.0 wt %, and Eu of 0 to 3.5 wt %, having an emission spectrum with a maximum peak wavelength in a range from 400 to 500 nm under an excitation of the light in a wavelength range from 350 nm to 430 nm.

9. The phosphor according to claim 1, wherein in an X-ray diffraction pattern by a powder method using CoKα

ray, a diffraction peak with highest intensity is shown in a Bragg angle (2θ

) range from 35°

to 37°

, and further in the Bragg angle (2θ

) range from 23.6°

to 25.6°

, 33°

to 35°

, 39.7°

to 40.7°

, and 43°

to 44°

of an X-ray diffraction pattern by the powder method, two, two, one, and one characteristic diffraction peaks are observed, respectively and when a relative intensity of the diffraction peak with highest intensity observed in the Bragg angle (2θ

) range from 35°

to 37°

is defined as 100%, the relative intensity of the diffraction peaks is not less than 2.0% and not more than 40%.

10. The phosphor according to claim 1, wherein the crystal of a product phase included in the phosphor has an orthorhombic structure.

11. The phosphor according to claim 1, wherein a unit volume of a crystal lattice of the product phase included in the phosphor is not less than 345 Å

³ and not more than 385 Å

³.

12. The phosphor according to claim 1, wherein a lattice constant of the crystal lattice of the product phase included in the phosphor is a=7.85 Å

to 8.28 Å

, b=9.26 Å

to 9.58 Å

, and c=4.80 Å

to 4.92 Å

.

13. The phosphor according to claim 1, wherein the size (Dx) of a crystallite of the product phase included in a phosphor powder is 50 nm or more.

14. The phosphor according to claim 1, containing primary particles having particle size of 50 μ

m or less, and an aggregate in which the primary particles are aggregated each other, wherein an average particle size (D50) of the phosphor powder containing the primary particles and the aggregate is not less than 1.0 μ

m and not more than 50.0 μ

m.

15. A manufacturing method of the phosphor according to claim 1, comprising the steps of:

obtaining a mixture by weighing and mixing raw material powders of the phosphor;

obtaining a fired object by firing the mixture thus obtained in a firing furnace; and

obtaining the phosphor by pulverizing the fired object, wherein as an atmosphere gas during firing, any one of an inert gas such as nitrogen and rare gas, ammonia, mixed gas of ammonia and nitrogen, or the mixed gas of nitrogen and hydrogen is used in the step of obtaining the fired object by firing the mixture.

16. The manufacturing method of the phosphor according to claim 15, wherein the gas containing 80% or more of nitrogen gas is used as the atmosphere gas in the firing furnace.

17. The manufacturing method of the phosphor according to claim 15, wherein the raw materials are fired, with the atmosphere gas in the firing furnace ventilated at 0.1 ml/min in the step of obtaining the fired object by firing the mixture in the firing furnace.

18. The manufacturing method according to claim 15, wherein the firing furnace is set in a pressurized state, with the atmosphere gas therein set at not less than 0.001 MPa and not more than 1.0 MPa.

19. The manufacturing method of the phosphor according to claim 15, wherein a crucible composed of nitride is used as a firing crucible.

20. A light emitting device, having the phosphor according to claim 1 and a light emitting part emitting light of a first wavelength and emitting the light from the phosphor having different wavelength from that of the first wavelength, with a part of or all of the light of the first wavelength as an excitation light.

21. The light emitting device according to claim 20, wherein the first wavelength means the wavelength in a range from 350 nm to 430 nm.

22. The light emitting device according to claim 20, wherein the light emitting part emitting the light of the first wavelength is a light emitting element (LED).