Pick your precursor! Tailoring the size and crystal phase of microwave-synthesized sub-10 nm upconverting nanoparticles. Issue 48 (27th November 2019)

• Record Type: Journal Article
• Authors: Halimi, Ilias; Rodrigues, Emille M.; Maurizio, Steven L.; Sun, Hui-Qiao Tina; Grewal, Manjot; Boase, Emma M.; Liu, Nan; Marin, Riccardo; Hemmer, Eva
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 48(2019)
• Page Start: 15364
• Page End: 15374
• Publication Date: 2019-11-27
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9tc04817k
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The influence of precursor chemistry on thermal decomposition and particle growth in a rapid microwave-assisted strategy was investigated, demonstrating the selective synthesis of small and ultrasmall luminescent lanthanide-doped NaGdF4 nanoparticles. Abstract : Small and ultrasmall β-NaGdF4 :Yb 3+, Er 3+ upconverting and near-infrared emitting nanoparticles were prepared by a rapid microwave-assisted strategy utilizing three different lanthanide (Ln) precursors: trifluoroacetates [Ln(TFA)3 ], oleates [Ln(OA)3 ], and acetates [Ln(Ac)3 ]. Assessment of their morphology, crystal phase, and photoluminescence revealed how the nature of the precursor has a great impact on the formation of these nanomaterials. In fact, our findings indicate a sizeable effect on the growth kinetics, which ultimately determined the nanoparticle size, crystal phase, and optical behavior. In a nutshell, the nanoparticles synthesized starting from [Ln(TFA)3 ] were the largest (5 to 9 nm) and featured the strongest emission. Those prepared from [Ln(OA)3 ] and [Ln(Ac)3 ], respectively, exhibited similar sizes in the ultrasmall size regime ( ca. 3 nm). The different thermal stabilities of the respective lanthanide precursors – inducing different pressure conditions in the microwave reaction vessel – are suggested to affect the growth mechanism of the nanoparticles. Ultimately, this allows for size control within the sub-10 nm realm. The developed approach was further demonstrated suitable for the growth of core/shell architectures, which greatly improved the emission brightness, while maintaining the particle size below 20 nm.