Facile synthesis of visible light excited La1-xGdxF3: Eu3+ micro-meter sphere using polyvinylpyrrolidone as a template

Lanthanide fluorides exhibited unique luminescent properties in terms of their low phonon energy can restrict the luminescence quenching and extend luminescent lifetimes. Here, a room-temperature co-precipitation method was used to synthesize europium(III) activated La_1-xGd_xF₃ solid phosphors. X-ray diffraction (XRD) data confirmed the crystalline phases of synthesized sample belongs to orthorhombic system. All the as-derived materials exhibited red luminescence (⁵D₀→⁷F₁) under the excitation at longer wavelengths (394 and 466 nm). The powder with the most intense emission was achieved in terms of 10 mol.% doping concentration (Eu content, La/Gd=1/9) and sample sintered at 700 °C. Scanning electron microscopy (SEM) investigated the morphology and crystalline of the samples, showing that many regular and large balls (5-10 μmol/L) were dispersed within the micro-meter scale composites. We proved that the above crystal growth structures were controllable and predicable based on the surface functionalization by polyvinylpyrrolidone ligand.