Eu2+在Ba2Ca(BO3)2中的发光特性及浓度猝灭

采用高温固相法,以CaCO₃ (A.R)、BaCO₃ (A.R)、H₃BO₃ (A.R)和Eu₂O₃ (99.99%)为原料制备了Ba₂Ca(BO₃)₂∶Eu²⁺绿色发光材料,测量了材料的晶体结构、发光特性及色坐标等。Ba₂Ca(BO₃)₂∶Eu²⁺材料的激发光谱覆盖200~500 nm的紫外-可见光区。在400 nm近紫外光激发下,材料的发射光谱为一主峰位于537 nm的非对称宽谱,对应于Eu²⁺的4f⁶5d¹→4f⁷特征跃迁。研究发现,随Eu²⁺掺杂浓度的增大,Ba₂Ca-(BO₃)₂∶Eu²⁺材料的发射强度呈现先增大、后减小的变化趋势,最大发射强度对应的Eu²⁺掺杂摩尔分数为2%。造成发射强度下降的原因为浓度猝灭,其机理为电偶极-电偶极相互作用。依据晶格常数及实验光谱数据,得出临界距离R_c分别为2.64 nm和2.11 nm。随Eu²⁺掺杂浓度的增大,Ba₂Ca(BO₃)₂∶Eu²⁺材料的色坐标变化微小。计算得到Ba₂Ca(BO₃)₂∶2%Eu²⁺的转换效率约为72%。

Luminescent Properties and Concentration Quenching of Eu2 + in Ba2Ca( BO3 ) 2

Ba2Ca(BO3)2∶Eu2+ phosphor was synthesized by a high temperature solid-state method.CaCO3(A.R),BaCO3(A.R),H3BO3(A.R) and Eu2O3(99.99%) were used as raw materials.Its crystal structure,luminescent characteristics and Commission International de l’Eclairage(CIE) chromaticity coordinates values were measured.Under the ultraviolet to visible light irradiation,Ba2Ca(BO3)2∶Eu2+ shows an asymmetrically single green emission band with a maximum at 537 nm,which corresponds to the 4f65d1→4f7 transition of Eu2+.The emission intensity of Ba2Ca(BO3)2∶Eu2+ was influenced by Eu2+ molefraction,at first,it increases with the increase of Eu2+ mole fraction,and reaches a maximum value at 2%Eu2+,then decreases with further increasing its concentration because of the concentration quenching effect.And the concentration quenching mechanism is verified to be dipole-dipole interaction.According to the crystal structure data and the experimental spectral data,the critical distances(Rc) can be obtained,and are 2.64 nm and 2.11 nm,respectively.Moreover,with increasing the Eu2+ doped content,the CIE chromaticity coordinates of the samples were slightly varied.For Ba2Ca(BO3)2∶2%Eu2+,the quantum efficiency is approximately 72%.