Multicolor and bright white upconversion luminescence from rice-shaped lanthanide doped BiPO4 submicron particles

In this paper, uniform rice-shaped lanthanide doped BiPO4 upconversion submicron particles have been successfully synthesized via a facile room-temperature co-precipitation reaction and subsequent calcination route. The morphology, phase transformation and upconversion luminescent properties of synthesized submicron particles (SMPs) were characterized by using different analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TG-DSC) and upconversion luminescence (UCL) spectra. The transformation from hexagonal phase to monoclinic phase is crucial for upconversion luminescent properties due to the loss of water molecules in the lattice of hexagonal phase. With different variety and concentration of the dopant Ln3+ (Ln = Yb, Er, Tm and Ho) ions, the obtained samples present bright green, blue, and red upconversion emissions under a 980 nm continual wave laser diode excitation. Multicolor and bright white upconversion emissions have also been obtained by precisely adjusting the dopants concentration in the host lattice.