Growth and optical properties of YBa3B9O18:Ce crystals

YBa3B9O18:Ce scintillation crystals with a size up to 25×12×5 mm3 were grown by the Czochralski method. The X-ray excited luminescence (XEL) spectrum of YBa3B9O18:Ce4+ crystal showed a strong emission at 400 nm similar to a pure YBa3B9O18 crystal. A strong emission shifted to 385 nm and an additional emission at 325 nm was observed due to Ce3+ after annealing the crystal in N2. A new luminescence at 948 nm appeared under the excitation of a 532 nm laser. The refractive indices of the crystal measured by a prism method showed that the crystal is a negative uniaxial crystal. The birefringence is 0.12 in the visible light region, which is comparable to that of a β-BaB2O4 crystal. The refractive indices and transmittance both support that the crystal is strongly anisotropic. The large birefringence and luminescent properties make YBa3B9O18:Ce an attractive optical crystal.