【摘要】 采用基于密度泛函理论的相对论性离散变分和嵌入团簇方法,计算了掺钇PbWO₄晶体中多种相关缺陷的电荷分布和不同团簇缺陷结合能,并讨论了相关缺陷的电荷补偿机制。V_Pb是掺Y钨酸铅晶体中主要的电荷补偿方式。Y₍Pb³⁺+V_Pb相关缺陷可能是晶体中存在的主要缺陷,其中[2(Y_Pb³⁺)-V_Pb’’]在晶体中更稳定。缺陷态[2(Y_Pb³⁺)-V_Pb’’]和[(Y_Pb³⁺)-V_Pb’’]的态密度分布及其激发能的计算结果表明:掺Y晶体利O_2p→W_5d的跃迁能量均为4.3eV,使周围WO₄^2-禁带宽度增大,可改善420nm与350nm的吸收,并通过减少V_Pb-V_O联合空位可有效抑制PbWO₄晶体的本征吸收。晶体中掺Y与掺La对发光影响不同,掺Y可敏化PWO晶体的蓝发光。更多还原

【Abstract】 The electronic structures of the defects related to Y dopants in PbWO4 crystals were investigated by the relativistic self-consistent discrete variational embedded cluster method. We focused on the binding energy and the charge compensation mechanism of correlative defects. It is shown Vpb is the main charge compensation in PbWO4: Y crystal. Ypb3 + + Vpb defects might be the main defects in Y dopants crystal. Among of them, [2(Ypb3+ ) - Vpb’’ ] is most stable. By the transition state method, we found that the transition energy of O2p →W5d is about 4.3eV in [2( YPB3+ ) - Vpb" ] and [(Ypb3+ ) - Vpb" ] defects of PbWO4: Y crystal. It is suggested that Y dopants should increase the forbidden band width of arrounding WO42- and improve 420nm and 350nm absorption bands in PbWO4 crystal. Also Vpb - VO defects are reduced by doped Y, which could restrain the 350nm absorption. Moreover, Y dopants could sensitize the blue luminescence band of PWO crystal, which is different from that by La dopants.更多还原