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 YF3: xEu3+ with different Eu3+ ions doping concentrations was explored by first-principles calculations based on density functional theory (DFT). As calculated, the YF3 host had an indirect bandgap of 7.68 eV. From all calculation results we got, the band structure of YF3: xEu3+ 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 YF3: xEu3+ phosphors with leaf-like, spindle-like, pecan-like, and granular-like morphologies were obtained by changing the RE3+/NaF ratio via a microwave hydrothermal method. At the same time, the formation process of granule-like YF3: Eu3+ was explored through time-dependent experiments. Furthermore, the fluorescence performance of YF3: xEu3+ was studied in detail. The as-obtained YF3: xEu3+ can exhibit orange-red emission under ultraviolet excitation because of the magnetic dipole of the 5D0–7F1 transition of Eu3+ 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 Eu3+ ions doping concentration were x = 0.10, which is highly consistent with the calculation result.