Factors for determining photoluminescence properties of YBO ₃: Ce³⁺ phosphor prepared by hydrothermal method

YBO₃:Ce³⁺ blue-emitting phosphors were prepared from boric acid and nitrates of yttrium and cerium(III) by hydrothermal method. An excess amount of boric acid, prolonged aging, high temperature, and a high pH value promote the formation of crystalline YBO₃. The higher crystallinity results in the higher photoluminescence (PL) intensity corresponding to the 5d-4f transition of Ce³⁺ under the irradiation of near-UV light. The PL intensity also depends on the pH value of precursor suspension and the nominal Ce³⁺ concentration, where the sample prepared at pH = 8 and Ce/(Y + Ce) = 0.25-0.5 at% shows the maximum PL intensity. In addition, the hydrothermally prepared sample shows the characteristic photobleaching behavior under the continuous irradiation of near-UV light. These results suggest that the crystallinity of the host YBO ₃ crystal and the homogeneity of substituted Ce³⁺ ions play significant roles in the PL properties.