Patent ID: 7382033

Claim:
A luminous body with a prolonged fluorescence lifetime, wherein the luminous body comprises silicate-germanate and is doped with europium to improve its thermostability, wherein the luminous body comprises an additional dopant and corresponds to the empirical formula: M′ a M″ b (Si 1-z Ge z ) c (Al,Ga,In) d (Sb,V,Nb,Ta) e O (a+b+2c+3d/2+5e/2−n/2) X n :Eu x ,R y wherein: M′ represents one or more elements selected from the group consisting of calcium (Ca), strontium (Sr), barium (Ba), and zinc (Zn); M″ represents one or more elements selected from the group consisting of magnesium (Mg), cadmium (Cd), manganese (Mn), and beryllium (Be); R represents one or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sn, and Sb; X represents an ion selected from the group consisting of fluorine (F), chlorine (Cl), and bromine (Br) to balance the charge; and 0.5≦a≦8, 0≦b≦5, 0<c≦10, 0≦d≦2, 0≦e≦2, 0≦n≦4, 0≦x≦0.5, 0≦y≦0.5, and 0<z<1.