Preparation method of rare earth ion doped lanthanum borate crystal phase controllable luminescent powder

The invention discloses a preparation method of rare earth ion doped lanthanum borate crystal phase controllable luminescent powder, and relates to a preparation method of a rare earth doped luminescent material. The preparation method adopts La2O3 (99.99%), Eu2O3 (99.99%), analytically pure boric acid (H3BO3), and citric acid as raw materials. The preparation method comprises the following steps: (1) preparing a rare earth compound nitrite (lanthanum nitrate and europium nitrate) mixed solution; (2) adding a different amount of citric acid; (3) adding a different amount of boric acid; (4) performing a reaction with a precursor solution at different temperatures and times to form a gel; (5) performing pre-combustion and grinding; and (6) performing heat treatment for 2 hours at different temperatures, and performing grinding to obtain powder. The method is simple in preparation process, and has the advantages of uniformity at a molecular level of a sol-gel method and short period of a low-temperature self-com