Synthesis, characterization and formation mechanism of pompon-like Lu2O2SO4: Eu3+ phosphors via a facile homogeneous precipitation method followed by calcination

Abstract

A series of Eu3+ doped pompon-like Lu2O2SO4 phosphors with diameter of ~800 nm have been synthesized by commercial available lutetium oxide (Lu2O3), nitric acid (HNO3), europium nitrate (Eu(NO3)3·6H2O), urea (CO(NH2)2), ammonium sulfate ((NH4)2SO4) and ammonia (NH3·H2O) as the starting materials via a facile homogeneous precipitation method followed by a subsequent calcination process. The as-prepared products were well characterized by X-ray powder diffraction (XRD), thermogravimetry and differential scanning calorimeter (TG-DSC), flourier transform infrared spectra (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra. Studies have shown that the molar ratio of Lu3+:(NH4)2SO4:CO(NH2)2 is very important in the homogeneous precipitation process, and the optimal ratio is selected as 1:25:50. In the subsequent calcination process, the effect of calcination temperature on the target product was studied and the optimal calcination condition is the calcination temperature of 800 °C for 2 h in air. And the morphology mechanism of the pompon-like Lu2O2SO4 is explored, detailed investigation showed the formation of pompon structure is accompanied by two different growth mechanisms. According to PL spectra, under 396 nm ultraviolet (UV) light excitation, the strongest emission peak for the Lu2O2SO4:x%Eu3+ phosphors located at 620 nm, which corresponds to the typical 5D0-7F2 transition of Eu3+ ions. The optimal doping concentration of Eu3+ ions in the Lu2O2SO4 host lattice is 6.0%, whose average lifetime τ and color correlation temperature (CCT) are calculated to be 39.558 μs and 1915 K, respectively.