Synthesis of three-dimensional flower-like BiOCl:RE ³⁺ (RE ³⁺  = Eu ³⁺ , Sm ³⁺ ) globular microarchitectures and their luminescence properties

Three-dimensional flower-like Eu ³⁺ and Sm ³⁺ -activated BiOCl globular microarchitectures were synthesized by the solvothermal method employing urea as a dispersing agent for the first time. The crystal structure, morphologies and luminescence properties of Eu ³⁺ and Sm ³⁺ doped BiOCl have been systematically investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) and spectroscopy, respectively. The unit cell volumes show a nearly linear decrease by about 0.18 and 0.15% with increasing Eu ³⁺ and Sm ³⁺ concentration up to 9 mol%, respectively. All of the prepared samples show flower-like globular microarchitectures with an average diameter about 3–5 μm with different Eu ³⁺ and Sm ³⁺ concentrations. Possible formation mechanism for the flower-like microarchitectures is proposed on the basis of time-dependent experiment. Both BiOCl:Eu ³⁺ and BiOCl:Sm ³⁺ samples show a strong red emission corresponding to the ⁵ D ₀  →  ⁷ F ₄ transition (700 nm) of Eu ³⁺ and ⁴ G _5/2  →  ⁶ H _7/2 transition (600 nm) of Sm ³⁺ , respectively. This work sheds some light on the design and preparation of red-emitting phosphors with novel microstructures.