A Novel 3D Architecture of GdPO4 Nanophosphors: Multicolored and White Light Emission

Homogeneous monoclinic GdPO4 particles composed of three intersecting lance-shaped crystals forming a penetration twin have been synthesized following a very restrictive, simple, and fast (10 min) method consisting of the hydrothermal reaction of gadolinium acetylacetonate with H3PO4 in a mixture of ethylene glycol and water at 180 °C. Slightly increasing the amount of water in the solvent mixture leads to hexagonal rodlike GdPO4·0.5H2O nanoparticles, whereas the variation of the Gd source, PO4 source, aging temperature, and polyol type gave rise to heterogeneous particles. The synthesis procedure is also suitable for the preparation of Eu3+-, Tb3+-, and Dy3+-doped GdPO4 particles with the same morphology and crystalline structure as the undoped materials. The effect of the doping level on the luminescent properties of the twinlike nanophosphors was evaluated, finding optimum doping levels of 5, 5, and 1% for the Eu3+-, Tb3+-, and Dy3+-doped materials, respectively. The twinlike GdPO4 nanophosphors were found to be more efficient than the rodlike GdPO4 ones in terms of emission intensity. Finally, a solid-state single-phase white-light-emitting nanophosphor has been fabricated for the first time in this system by triply doping the GdPO4 twined particles with appropriate concentrations of Eu3+, Tb3+, and Dy3+ and exciting through the Gd–Ln energy-transfer band at 273 nm. In addition to this energy transfer band, other energy charge transfer processes among the three dopants (Eu3+, Tb3+, and Dy3+) have been observed in the triply doped material.