Yb^(3+)掺杂浓度对LaF_3晶相及其上转换光谱的影响

Effect of Ions Concentration of Yb^(3+) on Crystal Structure and Upconversion Luminescence of LaF_3 Microcrystals

LaF3微米晶的晶相(斜方相和六角相)及其上转换发光光谱可以通过精确调节Yb3+的摩尔掺杂浓度来控制。利用简单的水热法合成了Yb3+和Tm3+共掺杂的LaF3,YF3和NaYF4三种不同基质的氟化物纳米晶。XRD分析表明,当Tm3+的掺杂浓度不变,仅Yb3+的摩尔掺杂浓度从10%提高到20%,就可以使基质结构由六角相过渡到斜方相。实验结果表明,具有较大离子半径的稀土离子由于增强的偶极化率,更容易使电子云产生畸变,有利于基质斜方相结构的形成。

The LaF3 microcrystals could be rationally tuned inphase（orthorhombic or hexagonal） and upconversion emission spectra through use of trivalent ytterbium dopant ions introduced at precisely defined concentrations.Tm3＋/Yb3＋ codoped LnF3（Ln=Y,La） and NaYF4 microcrystals were synthesized using a simple hydrothermal method.XRD analysis of Tm3＋/Yb3＋ codoped LaF3 microcrystals showed that 20% Yb3＋ doping was sufficient for hexagonal LaF3 microparticles to crystallize completely in the orthorhombic phase.Consequently,the results approved that the lanthanides with large ionic radii exhibited a high tendency towards electron cloud distortion owing to increased dipole polarizability,and thus favored the orthorhombic structures. 更多