Controlled synthesis and tuned fluorescence properties of NaGdF₄:Yb, Er up-conversion nanocrystals through one-step hydrothermal approach

Abstract

The properties of NaGdF₄:Yb, Er nanomaterials tuned by synthesis conditions have always been one of the research hotspots in the field of upconversion nanomaterials. In this work, NaGdF₄:Yb, Er upconversion nanomaterials capped with oleic acid (OA) molecules were prepared by one-step hydrothermal method. Controlling the fluorescence properties of NaGdF₄:Yb, Er nanomaterials by changing the synthesis conditions were principally investigated. The results showed that the crystalline state of the as-prepared upconversion nanomaterials tended to be intact and fluorescence emission capability enhanced when the reaction temperature increased from 140 °C to 160 °C, 180 °C and the reaction time extended from 6 h to 18 h. From 0.00 mmol to 0.75, 2.25, 5.00, 8.75, 12.50, 17.50 mmol of sodium hydroxide amount, the synthesized upconversion nanoparticles (UCNPs) transferred from orthorhombic GdF₃ to hexagonal β-NaGdF₄. And when the amount of sodium hydroxide was 2.25 mmol, the as-prepared nanoparticles exhibited stronger luminescence intensity. The ratio of Re³⁺ (Gd³⁺:Yb³⁺:Er³⁺) could also affect the properties of the as-prepared UCNPs. The nanomaterials emitted relatively stronger fluorescence when the ratio among Gd³⁺, Yb³⁺, Er³⁺ was 78:20:2. This work provides solid foundation for further theoretical study and practical application of NaGdF₄:Yb, Er nanomaterials.

Keywords:

• Upconversion nanomateirals
• NaGdF4
• reaction conditions
• micro-structure
• fluorescence properties

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Project of Qiqihar Academy of Medical Sciences (QMSI2017ZD01).