Electronic structure, morphology-controlled synthesis, and luminescence properties of YF3: Eu3+
Studying electronic structure plays a key role in improving the photoluminescence (PL) properties of materials. Therefore, the electronic structure of YF 3 : x Eu 3+ with different Eu 3+ ions doping concentrations was explored by first-principles calculations based on density functional theory (DFT). As calculated, the YF 3 host had an indirect bandgap of 7.68 eV. From all calculation results we got, the band structure of YF 3 : x Eu 3+ exhibited the smallest direct band gap of 6.54 eV when the value of x was 0.10. This small direct band gap is beneficial to obtain excellent emission intensity. Besides, the morphologies and sizes have a significant influence on the fluorescence intensity of the products. A series of YF 3 : x Eu 3+ phosphors with leaf-like, spindle-like, pecan-like, and granular-like morphologies were obtained by changing the RE 3+ /NaF ratio via a microwave hydrothermal method. At the same time, the formation process of granule-like YF 3 : Eu 3+ was explored through time-dependent experiments. Furthermore, the fluorescence performance of YF 3 : x Eu 3+ was studied in detail. The as-obtained YF 3 : x Eu 3+ can exhibit orange-red emission under ultraviolet excitation because of the magnetic dipole of the 5 D 0 – 7 F 1 transition of Eu 3+ ions. After comparing the luminescence properties of samples with different morphologies, we found that the sample with granule-like morphology had the highest orange-red emission intensity. The experimental result proved that the appropriate Eu 3+ ions doping concentration were x = 0.10, which is highly consistent with the calculation result. The great orange-red emission intensity was obtained by adjusting the electronic structure and morphology of the YF 3 : x Eu 3+ . The electronic structures of YF 3 : x Eu 3+ can be altered by changing Eu 3+ doping concentrations. The morphologies can be regulated by changing the RE 3+ /NaF ratio. Besides, the formation process of granule-like YF 3 : 0.1Eu 3+ was explored through time-dependent experiments.
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