▎ 摘　　要

NOVELTY - Preparing a divalent europium-activated cyan fluorescent powder comprises obtaining compound raw materials of each element based on the stoichiometric ratio of chemical formula having magnesium-aluminum-europium complex (Mg1-x-yRyAl2-zDzO4-mQm:xEu2+), mixing and processing to obtain a raw material mixture, where R is lithium, sodium and/or zinc, D is gallium, indium, yttrium and/or scandium, Q is nitrogen and/or fluorine and x is 0-0.2, y is 0-0.2, z is 0-0.5 and m is 0-0.3, providing carbon-containing reducing atmosphere, sintering the raw material mixture and post-treating to obtain the divalent europium-activated cyan fluorescent powder. USE - The method is useful for preparing a divalent europium-activated cyan fluorescent powder. ADVANTAGE - The powder: adopts carbon-containing reducing atmosphere, which is weaker than the strong reducing gas, so the reduction degree of the europium-containing compound is small; reduces the europium (III) to europium (II) under weak reducing condition and exhibits broadband emission and excellent thermal stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: a cyan fluorescent powder activated by divalent europium, which is prepared by above method. The cyan fluorescent powder has a cubic spinel crystal structure, and europium (II) is the light-emitting center; and a light-emitting device comprising a light source and a luminescent material. The luminescent material is a divalent europium-activated cyan fluorescent powder.