Growth of β-NaYF4:Eu3+ Crystals by the Solvothermal Method with the Aid of Oleic Acid and Their Photoluminescence Properties

Abstract

Lanthanide-doped hexagonal β-NaYF4 crystals have received much attention in recent years due to their excellent photoluminescence properties. However, lanthanide-doped β-NaYF4 crystals with micron and submicron scales as well as uniform morphology have received less attention. In this study, Eu3+-doped β-NaYF4 (β-NaYF4:Eu3+) crystals of micron and submicron size scales were synthesized using the solvothermal method with ethylene glycol as the solvent. The β-NaYF4:Eu3+ crystals were highly crystallized. A comparison of the characteristics of the β-NaYF4:Eu3+ crystals synthesized with and without the use of oleic acid as a surfactant was conducted. It was found that the utilization of oleic acid as a surfactant during their synthesis greatly decreased their particle size from micron to submicron scale, while adding a small amount of ethanol further reduced their particle size. In addition, they exhibited much smoother surfaces and more uniform morphologies, which were hexagonal prism bipyramids. The microstructural characteristics and photoluminescence properties of the β-NaYF4:Eu3+ crystals were studied in detail. Results showed that β-NaYF4:Eu3+ crystals prepared with the aid of oleic acid as a surfactant during their synthesis exhibited stronger photoluminescence.

Stress‐Induced Structural Phase Transition in Polystyrene/NaYF4: Eu3+ Photoluminescent Electrospun Nanofibers

“…NaYF 4 nanophosphors show a phase transformation in the structure from α-NaYF 4 (cubic) to β-NaYF 4 (hexagonal) by changing external parameters like temperature and fabrication process. The lanthanide-doped hexagonal phase of NaYF 4 nanocrystals exhibits marvelous luminescence properties because of its low phonon energy [23][24][25][26].…”

Luminescent Ink Based on Upconversion of NaYF4:Er,Yb@MA Nanoparticles: Environmental Friendly Synthesis and Structural and Spectroscopic Assessment

“…In another approach, the luminescent host material is constituted by NaYF 4 nanoparticles, synthesized by hydrothermal methods with oleic acid (OA) and used as surfactants [ 16 , 17 , 18 , 19 ]. The UCNPs produced using this approach are inherently capped with hydrophobic ligands because OA is a fatty acid, which contains an alkenyl group (–HC = CH–).…”