Red fluorescent material, method for producing red fluorescent material, white light source, illuminating device, and liquid crystal display

1. A red fluorescent material containing an element A, europium (Eu), silicon (Si), carbon (C), oxygen (O), and nitrogen (N), at an atomic ratio of the following composition formula (1):

[A (m-x) Eu x ][Si (9-y) C y ]O n N [12-2(n-m)/3]

wherein, in a PLE (Photo Luminescence Excitation) spectrum, a relative value of a luminescence intensity of 550 nm excitation wavelength when a luminescence intensity of 400 nm excitation wavelength is defined as 1 is not more than 0.85 and not less than 0.46,

wherein the element A is at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), and

m, x, y, and n satisfy 3<m<5, 0<x<1, 0<y<9, and 0<n<10, respectively.

2. The red fluorescent material according to claim 1 , wherein, in the composition formula (1), a relation of 0.045≦x≦0.180 is satisfied.

3. The red fluorescent material according to claim 1 , wherein,

in the composition formula (1), the element A includes at least calcium (Ca) and strontium (Sr), and

when each of atomic ratios of Ca, Sr, and another group 2 element is α, β, and γ, respectively (m=α+β+γ), a relation of 0<α/(α+β)≦0.2 is satisfied.

4. The red fluorescent material according to claim 1 , wherein, in the PLE spectrum, a relative value of a luminescence intensity of 550 nm excitation wavelength when a luminescence intensity of 400 nm excitation wavelength is defined as 1 is not more than 0.80 and not less than 0.65.

5. A method for producing a red fluorescent material, comprising:

mixing a carbonate compound of an element A, europium nitride, silicon nitride, and melamine to form a mixture so that the element A, europium (Eu), silicon (Si), carbon (C), oxygen (O), and nitrogen (N) are contained at an atomic ratio of the following composition formula (1):

[A (m-x) Eu x ][Si (9-y) C y ]O n N [12-2(n-m)/3]

burning the mixture to form a burned material; and

pulverizing the burned material obtained by the burning to obtain a red phosphor in which, in a PLE (Photo Luminescence Excitation) spectrum, a relative value of a luminescence intensity of 550 nm excitation wavelength when a luminescence intensity of 400 nm excitation wavelength is defined as 1 is not more than 0.85 and not less than 0.55,

wherein the element A is at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba); and

m, x, y, and n satisfy 3<m<5, 0<x<1, 0<y<9, and 0<n<10, respectively.

6. The method for producing a red fluorescent material according to claim 5 , wherein the burning of the mixture and the pulverizing of the burned material obtained by the burning are performed repeatedly.

7. A white light source, comprising:

a blue light-emitting diode formed on an element substrate; and

a kneaded material which is obtained by kneading a red phosphor and a green or yellow phosphor with a transparent resin and is arranged on the blue light-emitting diode,

the red phosphor containing an element A, europium (Eu), silicon (Si), carbon (C), oxygen (O), and nitrogen (N), at an atomic ratio of the following composition formula (1):

[A (m-x) Eu x ][Si (9-y) C y ]O n N [12-2(n-M)/3]

wherein, in a PLE (Photo Luminescence Excitation) spectrum, a relative value of a luminescence intensity of 550 nm excitation wavelength when a luminescence intensity of 400 nm excitation wavelength is defined as 1 is not more than 0.85 and not less than 0.55,

wherein the element A is at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), and

m, x, y, and n satisfy 3<m<5, 0<x<1, 0<y<9, and 0<n<10, respectively.