Work

Synthetic Control over the Electron-Beam Stability of Upconverting Nanoparticles

Year: 2026

Type: article

Abstract: Electron microscopy (EM) is fundamental to nanocrystal characterization, but some structures degrade quickly under electron beams, limiting advanced structural characterization. Here, we introduce a synthetic strategy that combines layer-by-layer shell growth with in situ annealing to produce NaYb 0.8 Er 0.2 F 4 alloyed upconverting nanoparticles (UCNPs) with enhanced structural stability and optical properties. Using an automated synthesis platform to control precursor delivery and annealing cycles, high rare-earth ion concentrations are maintained during shell growth and annealing at high temperature, reducing luminescence quenching and degradation under electron beams. This in situ annealing layer-by-layer (ISA-LBL) approach gives rise to alloyed UCNPs (aUCNPs) with exceptional electron-beam stability, reducing beam-induced fractures and voids by >90% compared to conventionally synthesized aUCNPs. ISA-LBL aUCNPs also exhibit enhanced photoluminescence intensity and extended lifetimes, consistent with fewer quenching defects. This demonstrates a synthetic route to nanocrystals with enhanced structural integrity, increasing their compatibility with EM studies and their utility in ionizing environments.

Source: Nano Letters

DOI: 10.1021/acs.nanolett.6c00830

Authors: Xiao Qi, Peter Ercius, P. James Schuck, Bruce E. Cohen, Emory M. Chan

Institutions: Lawrence Berkeley National Laboratory, Molecular Foundry, Columbia University

Language: English

Topic: Luminescence Properties of Advanced Materials

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: green

Funders: Biological and Environmental Research, Defense Sciences Office, DARPA, Chemical Sciences, Geosciences, and Biosciences Division

Awards: G1678256886, G2037563265, G223002938, G5906783430