Phosphor, method of producing phosphor, light-emitting element, light-emitting device, and image display apparatus

A phosphor in which at least some of an element M in a phosphor host crystal represented by Mα(L, A)βXγ is substituted with Eu, in both Eu3+ and Eu2+ states, as an activation material, the phosphor having a composition represented by Formula:

• Mα(L, A)βXγ:Euδ,
• wherein M represents one or more elements (including at least Sr) selected from Mg, Ca, Sr, Ba, and Zn,
• L represents one or more elements selected from Li, Na, and K,
• A represents one or more elements selected from Al, Ga, B, In, Sc, Y, La, and Si,
• X represents one or more elements selected from O, N, F, and Cl, wherein X is not only N,
• α, β, γ, and δ satisfy 8.70≤α+β+γ+δ≤9.30,
• 0.00<α≤1.30,
• 3.70≤β≤4.30,
• 3.70≤δ≤4.30, and
• 0.00<δ≤1.30, and
• in a fluorescence spectrum obtained by irradiation with light having a wavelength of 260 nm, when a fluorescence intensity at a wavelength of 569 nm is represented by I0 and a fluorescence intensity at a wavelength of 617 nm is represented by I1, a fluorescence intensity ratio I1/I0 is 0.01 or more and 0.4 or less,
• wherein the phosphor is powdery such that, when an average particle size corresponding to a cumulative value of 50% in a volume frequency particle size distribution measured using a laser diffraction scattering method is represented by d50, d50 is from 0.1 μm or more to 50 μm or less.