Rare earth β-NaGdF4 fluorides with multiform morphologies: Hydrothermal synthesis and luminescent properties

In this paper, the synthesis of rare earth fluoride β-NaGdF4 with multiform morphologies via a facile hydrothermal method has been fulfilled. The phases and shapes of the products can be tuned by changing the experimental parameters, including F− source and pH value of mother liquor. The morphologies for the products range from submicrorods, submicrospheres, dumbbell-like nanorods, cobblestone-like particles to aggregates constructed from nanoparticles. The results indicate that F− source and pH value play a critical role in determining the morphologies of the final products. Additionally, we investigate the photoluminescence (PL) properties of Ce3+/Ln3+ (LnEu, Tb and Dy) codoped down-conversion (DC) and Yb3+/Er3+ (Tm3+, Ho3+) codoped up-conversion (UC) in β-NaGdF4 host lattices. In the process of DC photoluminescence, energy transfer has occurred. This energy transfer occurs through the energy migration process like S → Gd3+ → (Gd3+)n → A (S represents the sensitizer and A represents the activator) and the Gd3+ plays an intermediate role in the process.

Graphical abstractRare earth fluorides β-NaGdF4 nano/microstructures with multiform shapes and sizes as well as fruitful emission properties were synthesized by a simple hydrothermal process.Figure optionsDownload full-size imageDownload high-quality image (201 K)Download as PowerPoint slideResearch highlights► A facile and effective hydrothermal method was developed to prepare gadolinium fluorides (β-NaGdF4 and GdF3) with multiform morphologies and sizes by tuning the pH value and F− sources. ► Simplicity, low-costs, ease of scale-up, the diverse morphologies and relative greenness (aqueous solution) constitute the key traits of this method. ► Multicolor down-conversion and up-conversion emissions can be obtained in β-NaGdF4 host lattice by simply changing the kinds and concentrations of the doping rare earth ions.