Synthesis, Crystal Growth And Luminescence Of Silicate Bismuth (Bi₄Si₃O₁₂)

Scintillation crystals refers to the high-energy radiation such as x-rays, ?-rays or other radiation particles through certain crystals, due to ray or particle excitation, consequently emit visible photon, which is widely used in high energy physics, nuclear physics, medical imaging, and geological exploration and other fields.Both Bi4Si3O12(BSO) and BGO crystals have the same lattice structure, scintillation properties originate from Bi3+light performance. But decay time of BSO is a third of BGO, and raw materials are cheaper, and is an ideal material to replace the BGO. Recently, BSO was found that it is fit to use as a probe, which can be used to detect hundreds of Mev energy level particles, the comprehensive performance of BSO is much better in the field of double read than existing scintillation crystal materials such as BGO and lead tungstate (PbWO4). But the difference of BSO raw materials of Bi2O3 and SiO2 melting point and density is very big, as a result the growth of BSO is very difficult, prone to component segregation.In this paper, using the sol gel method, with stoichiometric four ethyl silicate Si(OC2H5)4 and bismuth nitrate Bi(NO3)3·5H2O as the precursors and acetic acid as the solvent, according to the stoichiometric ratio of ingredients, polycrystalline Bi4Si3O12(BSO) powders were synthesized and high heat sintering preparation,vertical Bridgman method is used to grow a large size high quality BSO transparent crystal. After processing is a=b=30mm, c=210mm rectangle, crystal surface have no obvious cracks, basically eliminate segregation phenomenon. In 200-800nm region, the BSO crystal transmittance reach maximum theoretical nearly 80%. The optical properties of BSO crystal are studied, scintillation characteristics test show that the crystal energy resolution was 18.9%, the relative light yield of the crystal was 7.2%compared with CsI(T1) for absorbed gamma rays energy.By solid phase method, [Bi(1-x-y) DyxTmy]4Si3Oi2 (x=1%, y=0.1%,0.5%,1%,1.5%,2%) powders were prepared. Under the excitation of 354nm UVA light, fluorescence emission spectrum shows that there are both yellow light emission of Dy3+and blue light emission of Tm3+, with the doping concentration of Tm3+increased, the emission intensity of Dy3+ increase first and then decrease, when the concentration of Tm3+ was 1%, the emission intensity of Dy3+ reach the maximum. The color coordinates (CIE) analysis results show that when the concentration of Tm3+were 0.5%,1%,1.5%, the light-emitting of the samples landed in the white area, the results suggest that Dy3+/Tm3+co-doped BSO powder is a potential phosphors which could be applied on the white LED.