Peasecod-Like Hollow Upconversion Nanocrystals with Excellent Optical Thermometric Performance.

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Trivalent lanthanide (Ln³⁺)-doped upconversion nanocrystals (UCNCs) offer unique optical properties compared to solid counterparts.
• Existing Ln³⁺-doped UCNCs are solid, limiting their potential applications.
• The fabrication of hollow Ln³⁺-doped UCNCs remains largely unexplored.

Purpose of the Study:

• To synthesize and characterize the first hollow Ln³⁺-doped UCNCs.
• To investigate the structural and optical properties of these novel hollow UCNCs.
• To explore their application as supersensitive luminescent nanothermometers.

Main Methods:

• Synthesis of Yb³⁺/Er³⁺-doped tetralithium zirconium octafluoride (Li₄ZrF₈:Yb/Er) UCNCs with a 2D layered crystal lattice.
• Utilizing first-principle calculations to understand the formation of the hollow nanoarchitecture.
• Characterization of optical properties, including upconversion luminescence and temperature sensing capabilities.

Main Results:

• Successful fabrication of peasecod-like hollow UCNCs based on Li₄ZrF₈:Yb/Er.
• First-principle calculations revealed the hollow structure is linked to hetero-valence doping in the 2D layered matrix.
• The hollow UCNCs exhibited abnormal green upconversion luminescence and superior temperature sensing performance (123–800 K).

Conclusions:

• This study reports the first hollow Ln³⁺-doped UCNCs, opening new avenues in nanomaterial fabrication.
• The unique hollow structure enhances optical properties for advanced applications.
• These hollow UCNCs demonstrate significant potential as highly sensitive luminescent nanothermometers with a broad operating range.