Yttrium aluminate, also known as yttrium aluminum oxide, YAG for short, also known as yttrium aluminum garnet. The chemical formula is Al5H5O12Y3, the molecular weight is 598.65800, and the CAS number is 12005-21-9. Except for the compound of yttrium, all other chemicals are reagent-grade. Yttrium acetate and yttrium nitrate can be prepared from high-purity yttrium oxide to avoid fluorescence interference of rare earth impurities. Y3Al5O12 can be prepared by alkoxide acetate method, nitrate method and homogeneous precipitation method. In the alkoxide acetate method, aluminum isobutanol and yttrium acetate undergo polymerization; In the nitrate method, 1mol/L yttrium nitrate solution and 1mol/L aluminum nitrate solution are mixed at the ratio of 3∶5; In the homogeneous precipitation method, 1mol/L yttrium nitrate solution and 1mol/L aluminum nitrate solution were added to 1mol/L urea solution, so that metal ions were co-precipitated in the form of hydroxide. The products prepared by these three methods all need to be ground in a mortar and then heated at 500℃ for 5 hours to be converted into oxides. When YAG is prepared by high-temperature solid-state reaction, it is easy to get blocky products, which need to be ground before use. In order to improve the resolution of fluorescent screen, practical luminescent materials need to have high chemical purity, uniformity and appropriate particle size. Flux BaF2 has an effect on YAG synthesis. High-purity YAG can be obtained by soft chemical method using BaF2 as flux at 1220℃. Sulfate solution combined with urea can be used for YAG synthesis. Urea is added to the solution, and the pH value of the solution is adjusted by the OH- generated by the slow hydrolysis of urea in water. Al(OH)3 was used as seed crystal to accelerate the precipitation of yttrium hydroxide, and it was synthesized at a proper temperature. Dissolve the oxide with dilute sulfuric acid to prepare solutions of Al2(SO4)3 and Y2(SO4)3 with appropriate concentration, then make high-purity Al(OH)3 with the solution of Al2(SO4)3, and add an appropriate amount of Al(OH)3 to make Y(OH)3 precipitate immediately, which is evenly mixed with Al(OH)3 to generate coprecipitation and precursor powder.