Hydrothermal method synthesis and luminescent properties of LaVO4:Eu3+ red phosphors

LaVO4: Eu3+ phosphors with high purity and crystallinity were successfully prepared by a hydrothermal method with the addition of polyvinylpyrrolidone over a wide pH range. The mechanism by which pH affects the evolution of crystal morphology and fluorescence properties was explored and analyzed. Finally, theoretical calculations combined with first-principles were used to study the electronic structure and optical properties of LaVO4 and Eu3+-doped LaVO4 with different structures. The results show that the surface of the samples formed under acidic conditions is rough. Under neutral conditions, the samples start to aggregate into blocks and their surfaces become relatively smooth. There is a strong red emission at 617 nm(5D0→7F2), when the fluorescence intensity is optimal at pH 7. This also indicates that the doping of Eu3+ improves the fluorescence intensity. However, in the fluorescence decay curve fitting results show that the decay time is better for pH 9. The calculations show that the doping of Eu3+ reduces the band gap value of the LaVO4 system and increases the fluorescence intensity of the phosphor. In addition, the optical property calculations show that the monoclinic structure of LaVO4: Eu3+ has better fluorescence, which is consistent with the experimental results.