Phosphor, producing method thereof and light-emitting device employing the phosphor
The embodiment of the present disclosure provides a phosphor improved in the emission intensity maintenance ratio without impairing the emission intensity. The phosphor is a silicofluoride phosphor and shows an IR absorption spectrum satisfying the conditions of 0≤I 2 /I 1 ≤0.01 and 6.7≤(I 3 /I 1 )/C Mn . In those conditional formulas, I 1 , I 2 and I 3 are intensities of the maximum peaks in the ranges of 1200 to 1240 cm −1 , 3570 to 3610 cm −1 and 635 to 655 cm −1 , respectively, and C Mn is a weight percent of Mn contained the phosphor.
1. A phosphor represented by the following formula (1):
(K 1-p/k ,M p/k ) a (Si 1-x-y ,Ti x ,Mn y )F b (1)
in which M is at least one selected from the group consisting of Na and Ca; k represents the valence number of M and is an integer of 1 or 2; and a, b, p/k, x and y are numbers satisfying the conditions of
1.5≤a≤2.5,
5.0≤b≤6.5,
0≤p/k≤0.1,
0≤x≤0.3, and
0<y≤0.2, respectively;
said phosphor shows an IR absorption spectrum satisfying the conditions of
0≤I 2 /I 1 ≤0.01 and
6.7≤(I 3 /I 1 )/C Mn
in which I 1 is an intensity of the maximum peak in the range of 1200 to 1240 cm −1 , I 2 is an intensity of the maximum peak in the range of 3570 to 3610 cm −1 , I 3 is an intensity of the maximum peak in the range of 635 to 655 cm −1 , and C Mn is a weight percent of Mn contained therein.
2. The phosphor according to claim 1 , wherein said ratio of I 2 /I 1 satisfies the condition of 0≤I 2 /I 1 ≤0.005.
3. The phosphor according to claim 1 , wherein said numbers p/k and x in the formula (1) satisfy the conditions of p/k=0 and x=0, respectively.
4. The phosphor according to claim 1 , whose internal quantum efficiency η′ is 80% or more.
5. A light-emitting device comprising:
a light-emitting element radiating light with a peak in the wavelength range of 440 to 470 nm inclusive; and
a phosphor layer which contains the phosphor according to claim 1 .
6. The light-emitting device according to claim 5 , wherein said phosphor layer further contains another phosphor exhibiting an emission peak in the wavelength range of 520 to 570 nm inclusive.
7. A method for producing the phosphor according to claim 1 , comprising the steps of
(A) synthesizing a basic phosphor represented by the formula (1), and
(B) subjecting the basic phosphor synthesized in said step (A) to dehydration treatment at a temperature of 400 to 800° C. inclusive.
8. The method according to claim 7 , wherein said step (A) is either
(i) a step in which a Si-containing material and a Ti-containing material are combined with potassium permanganate and/or sodium permanganate and then made to react in a hydrofluoric acid aqueous solution, to synthesize the basic phosphor; or
(ii) a step in which a potassium-containing material and/or a sodium-containing material are added into a hydrofluoric acid aqueous solution in which a mixture of hexafluorosilicic acid with potassium or sodium hexafluoromanganate is beforehand dissolved, so that they are made to react to synthesize and obtain the basic phosphor by a co-precipitation method or a poor solvent precipitation method.
9. The method according to claim 7 , wherein said step (B) is carried out at a pressure of 0.0003 to 8 atmospheres inclusive.
10. The method according to claim 7 , wherein said step (B) is carried out in an atmosphere of a fluorine-containing inert gas.
11. The method according to claim 10 , wherein the atmosphere of said step (B) contains a fluorine compound having a boiling or sublimation point of 50 to 800° C. inclusive at the atmospheric pressure.