Nano-Crystallization of Ln-Fluoride Crystals in Glass-Ceramics via Inducing of Yb3+ for Efficient Near-Infrared Upconversion Luminescence of Tm3.

Jianfeng Li,Shupei Zheng,Qichao Zhao,Bai-Ou Guan,Yi Long,Zaijin Fang

doi:10.3390/nano11041033

Abstract

Transparent glass-ceramic composites embedded with Ln-fluoride nanocrystals are prepared in this work to enhance the upconversion luminescence of Tm3+. The crystalline phases, microstructures, and photoluminescence properties of samples are carefully investigated. KYb3F10 nanocrystals are proved to controllably precipitate in the glass-ceramics via the inducing of Yb3+ when the doping concentration varies from 0.5 to 1.5 mol%. Pure near-infrared upconversion emissions are observed and the emission intensities are enhanced in the glass-ceramics as compared to in the precursor glass due to the incorporation of Tm3+ into the KYb3F10 crystal structures via substitutions for Yb3+. Furthermore, KYb2F7 crystals are also nano-crystallized in the glass-ceramics when the Yb3+ concentration exceeds 2.0 mol%. The upconversion emission intensity of Tm3+ is further enhanced by seven times as Tm3+ enters the lattice sites of pure KYb2F7 nanocrystals. The designed glass ceramics provide efficient gain materials for optical applications in the biological transmission window. Moreover, the controllable nano-crystallization strategy induced by Yb3+ opens a new way for engineering a wide range of functional nanomaterials with effective incorporation of Ln3+ ions into fluoride crystal structures.

Highlights

Tm3+ doped materials possess UC luminescence in the NIR region at around 800 nm (3 H4 →3 H6 ), which is located in the biological transmission window, and the light in that region can penetrate biological tissues [10,11,12,13]
precursor glasses (PGs) samples were heated at 540 ◦ C for 5 and 10 h to obtain glass ceramic (GC) samples according to the differential scanning calorimetry (DSC) results in ref
To identify the crystalline phase in GCs, X-ray diffraction (XRD) patterns were performed on a X-ray diffractometer (Bruker, Fällanden, Switzerland) with Cu/Ka (λ = 0.1541 nm) radiation

Summary

Introduction

Tm3+ doped materials possess UC luminescence in the NIR region at around 800 nm (3 H4 →3 H6 ), which is located in the biological transmission window, and the light in that region can penetrate biological tissues [10,11,12,13]. Yb3+ -Tm3+ co-doped materials were more efficient candidates for NIR-to-NIR UC luminescence and were significant light sources for biologically non-destructive detection. A large number of investigations about Yb3+ -Tm3+ co-doped UC materials have been widely reported for achieving high-efficiency NIR UC luminescence [14,15,16,17,18,19,20]

Methods

Results

Conclusion