Growth and doping of BSO crystals for scintillation, laser and LED applications

Bismuth silicate (Bi₄Si₃O₁₂, BSO) single crystal is an important scintillator with the advantages of faster decay time, suitable melting point and density, low cost of raw materials. Doping is the way to improve scintillation properties of BSO crystal. Furthermore, doping makes it to be a multi-functional material, such as phosphor and laser crystal. In this review, we summarized the progress of BSO crystal in our lab. Large size BSO crystal has been grown by the modified Bridgman method, and it was found that the compositional segregation can be eliminated by doping more than 3% rare earth. Rare earth doped BSO crystals are phosphors with good thermal conductivity for high power LED applications. Dy:BSO emits yellow light and Dy/Tm:BSO emits white light. The spectroscopic characteristics of BSO crystals doped with Yb, Er, Ho and Tm have been investigated. The laser outputs of 0.73 and 0.65 W were realized in Ho:BSO and Tm:BSO crystals, respectively. BSO crystal emits light with the luminescence center of Bi³⁺ exited by X-ray or γ-ray. It was found that the light output of BSO crystals can be improved remarkable by doping small amount of Dy₂O₃ or about 1% Ta₂O₅. The mixed crystals of BSO and BGO, i.e., BGSO, are novel scintillation and laser materials and Re-doped BGSO crystals are expected to be potential laser materials.