Materials comprising an A/M/X compound are provided. An A/M/X compound is a compound comprising one or more A moieties, one or more M atoms and one or more X atoms, where the A moieties are selected from organic cations and elements from Group 1 of the periodic table, the M atoms are selected from elements from Group 14 of the periodic table, and the X atoms are selected from elements from Group 17 of the periodic table. The materials include two-phase materials.

A phosphor, having a general formula of K.sub.2[Si.sub.1-xGe.sub.x].sub.yF.sub.6:Mn.sub.1-y.sup.4+. The phosphor is excited to emit a light having a first main emission peak with a first maximum emission intensity and a first dominant wavelength, wherein a relative emission intensity S of the light of the phosphor is constantly greater than 85% across an temperature of the phosphor between 300 K and 470 K during operation, wherein S=(I.sub.T/I.sub.RT)*100%, I.sub.RT and I.sub.T are the first maximum emission intensity when the temperature of the phosphor is at 300 K and T during operation respectively, and 300 K<T470K.

Provided is a photochromic substance that has lower toxicity, exhibits good sensitivity in a visible light region, changes color deeply, has slow speed of color fading, has chemical and thermal stability, and has good durability. The photochromic substance has a composition represented by the formula:
Ba.sub.(a-b)Ca.sub.bMg.sub.cSi.sub.dO.sub.e:Fe.sub.fM.sub.gM.sub.h where 1.8a2.2, 0b0.1, 1.4c3.5, 1.8d2.2, e=(a+c+2d), 0.0001f, 0.0001g, 0h, M is at least one of Al and Eu, and M is at least one element selected from the group consisting of Na, K, Nd, Li, S, C, Ti, V, Mn, Cr, Cu, Ni, Co, Ge, Zn, Ga, Zr, Y, Nb, In, Ag, Mo, Sn, Sb, Bi, Ta, W, La, Ce, Pr, Nd, Sm, Gd, Er, Ho, Tb, Tm, Yb, Lu, P, Cd, and Pb.

A phosphor is described. In an embodiment a phosphor includes the material Ca(Al.sub.12-x-y-zMg.sub.xGe.sub.y)O.sub.19:(zMn.sup.4+), wherein 0<x, y, z<1. Furthermore, a light-emitting device containing the phosphor and a method for producing the phosphor are also described.

The present invention relates to compounds of the formula I,

(A.sub.2-2nB.sub.n).sub.x(Ge.sub.1-mM.sub.m).sub.yO.sub.(x+2y):Mn.sup.4+I

in which the parameters A, B, M, m, n, x, and y have one of the meanings according to claim 1. Furthermore, the invention relates to a process for the preparation of the compounds of the formula I, to the use of these compounds as conversion phosphors, and to an emission-converting material comprising at least one compound of the formula I. The present invention furthermore relates to a light-emitting device which comprises at least one compound of the formula I according to the invention.

A phosphor, having a general formula of K.sub.2[Si.sub.1-xGe.sub.x].sub.yF.sub.6:Mn.sub.1-y.sup.4+. The phosphor is excited to emit a light having a first main emission peak with a first maximum emission intensity and a first dominant wavelength, wherein a relative emission intensity S of the light of the phosphor is constantly greater than 85% across an temperature of the phosphor between 300 K and 470 K during operation, wherein S=(I.sub.T/I.sub.RT)*100%, I.sub.RT and I.sub.T are the first maximum emission intensity when the temperature of the phosphor is at 300 K and T during operation respectively, and 300 K<T470K.

The present application discloses an anti-deterioration red phosphor, and a preparation method and an application thereof, and relates to the field of phosphor materials technology. The anti-deterioration red phosphor of the present application comprises a core-shell structure, the core-shell structure comprises an inner core and an outer shell, the inner core and the outer shell are independently selected from substances shown in a chemical formula I, and the chemical formula I is A.sub.2M.sub.(1-x)F.sub.6:xMn.sup.4+. The present application enhances the moisture resistance and anti-deterioration resistance of the phosphor by controlling the atom percentage of Mn.sup.4+ to be the lowest in the innermost layer of the inner core and the highest in the outermost layer of the inner core. Additionally, by incorporating an outer shell with minimal or even no Mn.sup.4+ content to encapsulate the inner core of the phosphor, it helps maintain a higher luminescent efficiency in coordination with the inner core.