Fluoride fluorescent material and method for producing the same
A fluoride fluorescent material, comprising: a fluoride particles having a chemical composition represented by the formula (I): A 2 [M 1−a Mn 4+ a F 6 ] (I) wherein A is at least one cation selected from the group consisting of K + , Li + , Na + , Rb + , Cs + and NH 4 + ; M is at least one element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table; and variable a satisfies 0<a<0.2; and a thermally-conductive substance having a higher thermal conductivity than the fluoride particles, and that is arranged on at least a portion of a surface of the fluoride particles, and a method for producing the fluoride fluorescent material.
1. A fluoride fluorescent material, comprising:
a fluoride particle having a chemical composition represented by the formula (I):
A 2 [M 1−a Mn 4+ a F 6 ] (I)
wherein A is at least one cation selected from the group consisting of K + , Li + , Na + , Rb + , Cs + and NH 4 + ; M is at least one element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table; and variable a satisfies 0<a<0.2; and
a thermally-conductive substance having a higher thermal conductivity than the fluoride particle, being arranged on at least a portion of a surface of the fluoride particle, and being in the form of a particle.
2. The fluoride fluorescent material according to claim 1 , wherein the thermally-conductive substance is at least one selected from the group consisting of aluminum oxide, titanium oxide, beryllium oxide, zinc oxide, yttrium oxide, magnesium carbonate, diamond, boron nitride, aluminum nitride, rare-earth aluminate and metal oxynitride.
3. The fluoride fluorescent material according to claim 1 , wherein the thermally-conductive substance is partially surrounded by a crystal of the fluoride particle, and the thermally-conductive substance and the fluoride particle are in contact with each other on a plurality of surfaces thereof.
4. The fluoride fluorescent material according to claim 1 , wherein a portion of the thermally-conductive substance is embedded in the fluoride particle, and remaining portions of the thermally-conductive substance are exposed.
5. The fluoride fluorescent material according to claim 1 , wherein the thermally-conductive substance has a volume average particle size of 5 nm to 10 μm.
6. The fluoride fluorescent material according to claim 1 , wherein the thermally-conductive substance is aluminum oxide, and the aluminum oxide constitutes from 0.1% by weight to 20% by weight.
7. A method for producing a fluoride fluorescent material comprising:
the first step of contacting:
a first complex ion comprising a tetravalent manganese ion;
at least one cation selected from the group consisting of K + , Li + , Na + , Rb + , Cs + and NH 4 + ; and
a second complex ion comprising at least one element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table in a liquid medium containing hydrogen fluoride to obtain a fluoride particle having a chemical composition represented by the formula (I):
A 2 [M 1−a Mn 4+ a F 6 ]] (I)
wherein A is at least one cation selected from the group consisting of K + , Li + , Na + , Rb + , Cs + and NH 4 + ; M is at least one element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table; and variable a denotes a number that satisfies 0<a<0.2;
the second step of contacting the resultant fluoride particle with a thermally-conductive substance having a higher thermal conductivity than the fluoride particle in a liquid medium to obtain a fluoride particle having the thermally-conductive substance arranged on at least a portion of a surface thereof; and
the third step of contacting the fluoride particle, on which the thermally-conductive substance is arranged, with at least the cation and the second complex ion in a liquid medium.
8. The method for producing a fluoride fluorescent material according to claim 7 , wherein the first step comprises mixing:
a solution A containing at least the first complex ion, the second complex ion comprising at least one element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table and a fluorine ion, and hydrogen fluoride; and
a solution B containing at least the cation and hydrogen fluoride.
9. The method for producing a fluoride fluorescent material according to claim 7 , wherein the first step comprises mixing:
a first solution containing at least the first complex ion and hydrogen fluoride,
a second solution containing at least the cation and hydrogen fluoride, and
a third solution containing at least the second complex ion comprising at least an element selected from the group consisting of elements from Group 4 of the periodic table and elements from Group 14 of the periodic table and a fluorine ion to obtain a fluoride particle.
10. The method for producing a fluoride fluorescent material according to claim 7 , wherein the first step further comprises dispersing and/or particle-sizing the resultant fluoride particle.
11. The method for producing a fluoride fluorescent material according to claim 7 , further comprising, subsequent to the third step, the step of dispersing and/or particle-sizing the resultant fluoride particle.
12. A light emitting device comprising:
a fluoride fluorescent material according to claim 1 ; and
a light source that emits light in a wavelength range of from 380 to 485 nm.