Impact of molar ratio of total metal ions to precipitant on YAG:Ce nanophosphors synthesized by reverse titration coprecipitation

Systematic study on the impact of the pH value was performed in the preparation of YAG:Ce nanophosphor powders by reverse titration method. Therefore, we used wider range of the pH values from 5.0 to 8.3 for the synthesis, correlating closely with ratio R of the total metal ions to precipitant ammonium hydrocarbonate in the solution from 1:3 to 1:9. The calcination temperatures of 1050   °C and 1300   °C were tested for the crystallization of YAG:Ce nanophosphors. Acidic condition is more preferable for improved YAG:Ce nanophosphors through XRD spectra analysis for the type of crystals and the crystal size. The molar ratio Y 3+ /Al 3+ in the precursor was controlled at the level of R =1:3 to keep the stoichiometric ratio of YAG:Ce. SEM images showed the YAG:Ce nanophosphors prepared at acidic condition having smaller crystal size and improved dispersibility. Fluorescence spectrum displayed much stronger emission at R =1:3. The molar ratio R is a vital factor to control the quality of the YAG:Ce powders. The nanophosphors prepared at R =1:3 possessed the best fluorescence emission.