Luminescence properties of Ca(Y _0915-xGd _x Al _0.025Eu _0.06)BO ₄ phosphors under VUV irradiation

The major phase of post-treated Ca(Y _0915-xGd _x Al _0.025Eu _0.06)BO ₄ (0 ≤ x ≤ 0.3) phosphors was solid solutions of the constituent oxides, which had an orthorhombic warwickite-like structure. The calculated crystallite size of the Ca(Y _0915-xGd _x Al _0.025Eu _0.06)BO ₄ phosphors was ~36 nm. The Gd additive significantly enhanced both the charge transfer (CT) transition of O ^2--Eu ³⁺ and the absorption of the host materials, thereby resulting in an increase in emission intensity. The Ca(Y _0.715Gd _0.2Al _0.025Eu _0.06)BO ₄ phosphor showed the highest emission intensity at 593 nm, which was over five times as strong as that of a Gd-free Ca(Y _0.915Al _0.025Eu _0.06)BO ₄ phosphor. The addition of Gd was desirable for improving the photoluminescent properties of red-emitting Ca(Y _0.915 Al _0.025Eu _0.06)BO ₄ phosphors.