Phosphor, method for producing same and light emitting element
Provided is a phosphor which emits near-infrared light upon irradiation of visible light or ultraviolet light. A phosphor in an embodiment of the present invention includes an inorganic substance which contains at least an Eu element, an M[3] element (M[3] is at least one selected from the group consisting of Al, Y, La and Gd.), a Si element and nitrogen element, and also contains, if necessary, at least one element selected from the group consisting of M[1] element (M[1] is Li element.), an M[2] element (M[2] is at least one element selected from the group consisting of Mg, Ca, Ba and Sr.) and an oxygen element, while the phosphor has a maximum value of an emission peak at a wavelength in the range of 760 nm or more and 850 nm and less upon irradiation by an excitation source.
1. A phosphor comprising an inorganic substance comprising an Eu element, an M[3] element (M[3] is at least one kind of element selected from a group consisting of Al, Y, La, and Gd), a Si element, a nitrogen element, and, if necessary, at least one kind of element selected from a group consisting of an M[1] element (M[1] is a Li element), an M[2] element (M[2] is at least one kind of element selected from a group consisting of Mg, Ca, Ba, and Sr), and an oxygen element,
wherein the inorganic substance is represented by a composition of M[1] a Eu b M[2] c M[3] d Si e O f N g (where a+b+c+d+e+f+g=1) wherein parameters a, b, c, d, e, f, and g are represented by values respectively satisfying:
0≤a≤0.01,
0.006≤b≤0.15,
0≤c≤0.15,
0.001≤d≤0.07,
0.3≤e≤0.35,
0≤f≤0.05, and
0.5≤g≤0.56;
the phosphor emitting light having a local maximum value of a emission peak at a wavelength in a range of 760 nm or more and 850 nm or less upon irradiation by an excitation source.
2. The phosphor according to claim 1 wherein the inorganic substance is represented by a composition of M[1] a Eu b M[2] c M[3] d Si e O f N g (where a+b+c+d+e+f+g=1) wherein parameters a, b, c, d, e, f, and g are represented by values respectively satisfying:
a=0
0.006≤b≤0.13,
0≤c≤0.12,
0.0019≤d≤0.07,
0.3≤e≤0.35,
f=0, and
0.53≤g≤0.56.
3. The phosphor according to claim 1 wherein the inorganic substance is represented by a composition of (Eu, M[2]) x M[3] y Si 5 N 8 where x=2−1.5y and 0.1≤y≤0.5.
4. The phosphor according to claim 1 wherein the inorganic substance has the same crystal structure as any one of Eu 2 Si 5 N 8 , Ca 2 Si 5 N 8 , Sr 2 Si 5 N 8 , and Ba 2 Si 5 N 8 .
5. The phosphor according to claim 1 wherein the M[2] element is not included.
6. The phosphor according to claim 1 wherein the M[3] element is La single metal.
7. The phosphor according to claim 1 wherein the M[3] comprises at least La, and the La is contained in the range of 0.19 at % or more to 7 at % or less.
8. The phosphor according to claim 1 wherein the Eu element is contained in an amount of 0.6 at % or more.
9. The phosphor according to claim 1 wherein the inorganic substance is represented by Eu 2 Si 5 N 8 : La.
10. The phosphor according to claim 1 wherein the inorganic substance is represented by Sr 2 Si 5 N 8 : Eu, La.
11. The phosphor according to claim 1 wherein the inorganic substance is represented by Ba 2 Si 5 N 8 : Eu, La.
12. The phosphor according to claim 1 wherein the excitation source is light having a wavelength in a range of 300 nm or more and 600 nm or less.
13. The phosphor according to claim 1 wherein the excitation source is light having a wavelength thereof in a range of 300 nm or more and 600 nm or less, the phosphor emitting fluorescence having a spectral shape in which an emission intensity at 630 nm upon irradiation by the light is equal to or less than one-half of an emission intensity of a maximum value wavelength in a range of 760 nm or more and 850 nm or less.
14. A method of manufacturing a phosphor as recited in claim 1 comprising the steps of:
mixing a nitride or an oxide of Eu element, a nitride or an oxide of M[3] element, a nitride of Si element, and, if necessary, an at least one raw material selected from a group consisting of a nitride or an oxide of M[1], a nitride or an oxide of M[2], and an oxide of Si element; and
firing a mixed mixture at a temperature in a range of 1400° C. or higher and 2200° or lower.
15. A light-emitting element comprising: an excitation source and a phosphor,
wherein the excitation source emits light having a wavelength in a range of 300 nm or more and 600 nm or less and
wherein the phosphor comprises at least a phosphor as recited in claim 1 .
16. The light-emitting element according to claim 15 wherein the excitation source is a light emitting diode (LED) or a laser diode (LD).
17. The light-emitting element according to claim 15 further comprising one or more other phosphors emitting fluorescence having a maximum value (peak) at a wavelength in a range of 400 nm or more and 760 nm or less upon irradiation by the excitation source.
18. The light-emitting element according to claim 17 wherein the one or more other phosphors are respectively selected from a group consisting of α-sialon: Ce, β-sialon: Eu, α-sialon: Eu, CaAlSiN 3 : Ce, and (Ca, Sr)AlSiN 3 : Eu.
19. The light-emitting element according to claim 17 wherein the fluorescence has a spectral shape in which a minimum value of an emission intensity thereof is at least one-fifth (⅕) of a maximum value thereof in a wavelength range of 520 nm or more and 850 nm or less.