Disclosed are smoothing phosphors for AC LED lighting that are capable of prolonging the light emission time of an AC LED (or array of AC LEDs) during a cycle response to a, phase change of the alternating current to substantially reduce flicker. The smoothing phoshor of the present teachings comprises a matrix represented by the formula: (1krv)M.Math.(mp)X.Math.(n0.5x0.5y)Al.sub.2O.sub.3:(x+p)MnO, ySiO.sub.2, kEu, rR, vLi, wherein M is at least one of La.sub.2O.sub.3, Ce.sub.2O.sub.3, Gd.sub.2O.sub.3, Lu.sub.2O.sub.3, Ba.sub.2OF.sub.2, Sr.sub.2OF.sub.2, Ca.sub.2OF.sub.2, Ba.sub.2OCl.sub.2, Sr.sub.2OCl.sub.2, Ca.sub.2OCl, BaO, SrO, CaO, or ZnO; provided that when M comprises BaO, SrO, CaO, or ZnO, M does not comprise La.sub.2O.sub.3, Ce.sub.2O.sub.3, Gd.sub.2O.sub.3, Lu.sub.2O.sub.3, Ba.sub.2OF.sub.2, Sr.sub.2OF.sub.2, Ca.sub.2OF.sub.2, Ba.sub.2OCl.sub.2, Sr.sub.2OCl.sub.2, or Ca.sub.2OCl.sub.2; X is at least one of MgO or ZnO; R is at least one of Sm, Pr, Tb, Dy, Er, or Ho; m=0 to 2; n=4 to 11; x=0.005 to 1; y=0.005 to 1; p=0 to 1; k=0 to 0.2; r=0 to 0.2; and v=0 to 0.2.

The present invention provides a red light emitting glass ceramic and a preparation method thereof, and an LED/LD light emitting device. A.sub.2Al.sub.4Si.sub.5O.sub.18:Eu.sup.2+ cordierite of the red light emitting glass ceramic capable of realizing blue light excited red light emission is a crystal phase material, wherein A is at least one of Mg, Ca, Sr, Ba and Zn and at least comprises Mg. The present invention particularly provides the red light emitting glass ceramic taking a chemical formula A.sub.2Al.sub.4Si.sub.5O.sub.18:Eu.sup.2+ as a crystal phase. The present invention further provides a preparation method of the transparent glass ceramic. The glass ceramic comprising the crystal phase, with the chemical formula of Mg.sub.2Al.sub.4Si.sub.5O.sub.18:Eu.sup.2+, is excited by blue light to emit red light, the internal/external quantum efficiencies reaching up to 94.5%/70.6%, respectively.