Phosphor, producing method thereof, and light-emitting device employing the phosphor
Embodiments of the present invention provide a phosphor improved in the emission intensity maintenance ratio without impairing the emission intensity and further a light-emitting device employing that phosphor. The phosphor is activated by manganese and has a basic structure comprising at least one element selected from the group consisting of potassium, sodium and calcium; at least one element selected from the group consisting of silicon and titanium; and fluorine. In an IR absorption spectrum of the phosphor, the intensity ratio of the peak in 3570 to 3610 cm −1 to that in 1200 to 1240 cm −1 is 0.1 or less.
1. A phosphor:
having a basic structure comprising at least one element selected from the group consisting of potassium, sodium and calcium; at least one element selected from e group consisting of silicon and titanium; and fluorine;
wherein said phosphor is a manganese-activated fluoride phosphor; and shows an IR absorption spectrum in which the intensity ratio of the peak in the range of 3570 to 3610 cm − to that in the range of 1200 to 1240 cm −1 is 0.1 or less.
2. The phosphor according to claim 1 , represented by the following formula (A):
( K 1-p ,M p ) a ( Si 1-x-y ,Ti x ,Mn y ) F b (A)
in which
M is at least one selected from the group consisting of Na and Ca, and p, a, b, x and y are numbers satisfying the conditions of
0≤p≤0.1,
1.5≤a≤2.5,
5.5≤b≤6.5,
0≤x≤0.3, and
0≤y≤0.06, respectively.
3. The phosphor according to claim 2 , wherein p and x in said formula (A) are numbers satisfying the conditions of p=0 and x=0, respectively.
4. The phosphor according to claim 1 , wherein the internal quantum efficiency η′ is 70% 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 green or yellow light-emitting phosphor exhibiting an emission peak in the wavelength range of 520 to 570 nm inclusive.
7. The light-emitting device according to claim 6 , wherein said green or yellow light-emitting phosphor is selected from the group consisting of (Sr,Ca,Ba) 2 SiO 4 :Eu, Ca 3 (Sc,Mg) 2 Si 3 O 12 :Ce, (Y,Gd) 3 (Al,Ga) 5 O 12 :Ce, (Ca,Sr,Ba)Ga 7 S 4 :Eu, (Ca,Sr,Ba)Si 2 O 2 N 2 :Eu and (Ca,Sr)-αSiAlON.
8. A method for producing a phosphor, comprising:
synthesizing a manganese-activated fluoride phosphor having a basic structure comprising at least one element selected from the group consisting of potassium, sodium and calcium; at least one element selected from the group consisting of silicon and titanium; and fluorine; and then
immediately subjecting said phosphor to a stirring treatment in an organic solvent for 1 minute or more,
wherein said phosphor is synthesized in a manner where a potassium fluoride and/or a sodium fluoride are added into a hydrofluoric acid aqueous solution in which a mixture of hexatluorosilicic acid with potassium or sodium hexafluoromanganate is beforehand dissolved, so that they are made to react to synthesize the phosphor by a co-precipitation method or a poor solvent precipitation method.
9. The method according to claim 8 , wherein said synthesis is carried out in a reaction solution in which the hydrofluoric acid concentration is 20 wt. % or more.
10. The method according to claim 8 , wherein the amount of said organic solvent is 10 times or more the weight of said phosphor.