Energy Back Transfer Induced Color Controllable Upconversion Emissions in La₂MoO₆:Er³⁺/Yb³⁺ Nanocrystals for Versatile Applications

Abstract

Color controllable Er3+/Yb3+‐codoped La2MoO6 upconverting nanocrystals are successfully synthesized via a facile sol‐gel method. Under the irradiation of 980 nm light, the entire samples exhibit dazzling upconversion (UC) emissions arising from the intra‐4f transitions of Er3+ ions and the UC emission intensity is strongly dependent on the Yb3+ ion concentration. Moreover, by controlling the Yb3+ ion concentration, the emission color is changed from green to yellow and finally to red as a result of the energy back transfer from Er3+ to Yb3+ ions, which is further verified by the theoretically discussion based on the steady‐state rate expressions. The optical thermometric properties of the prepared nanocrystals based on the (2H11/2,4S3/2) thermally coupled levels of Er3+ ions are systematically studied by analyzing the temperature‐dependent green UC emission spectra in the range of 303–663 K. The maximum sensor sensitivity of resultant nanocrystals is determined to be 0.0083 K−1 at 510 K. Furthermore, the emitting color of the synthesized nanocrystals relies on the temperature. In addition, the heating effect induced by the excitation pump power is also investigated and the host lattice temperature is enhanced from 319 to 404 K with raising the pump power from 159 to 757 mW.

Enhanced luminescence properties of Eu3+ in La2MoO6 by nonsensitization of Bi3+

“…By evaluating the refinement parameters ( R wp , R p and χ 2 ), it can be suggested that the results are reliable. LMO:0.2Eu 3+ , 0.6Bi 3+ phosphors belong to I/42m(121) space group 25 . The unit crystal structure of the LMO host lattice is modeled using the Diamond software.…”

“…Therefore, in summary, La 3+ ions should be replaced by Bi 3+ ions or Eu 3+ ions. Meanwhile, the percentage differences among the dopants and substituted ion are calculated 25 as follows.where is the radius percentage difference. and denote the ionic radii of substituted ions and dopants, respectively.…”

“…LMO:0.2Eu 3+ , 0.6Bi 3+ phosphors belong to I/42m(121) space group. 25 The unit crystal structure of the LMO host lattice is modeled using the Diamond software. As shown in the inset of Figure 3, the La 3+ and Mo 6+ ions are coordinated with six and four oxygen atoms, respectively.…”

“…Therefore, in summary, La 3+ ions should be replaced by Bi 3+ ions or Eu 3+ ions. Meanwhile, the percentage differences among the dopants and substituted ion are calculated 25 as follows.…”

Synthesis and luminescence properties of Eu3+-activated BiF3 nanoparticles for optical thermometry and fluorescence imaging in rice root

“…As demonstrated above, the 5 D 1 level can be populated from the 5 D 0 level by means of thermal excitation, leading to the population redistribution between the 5 D 1 and 5 D 0 levels at high temperature. To further comprehend the temperature-induced population redistribution phenomenon, the temperature-induced population redistribution ability (PRA) was evaluated utilizing the following expression: 37,38 In this formula, I U , I L , A , Δ E , k , and T have the same meaning as described in eqn (1) . Based on the fitting results, the PRA value was calculated, as depicted in Fig.…”