Tunable Thickness and Photoluminescence of Bipyramidal Hexagonal β-NaYF₄ Microdisks

Abstract

Hexagonal β-NaYF4 was synthesized as capped bipyramidal microdisks solvothermally from yttria (Y2O3), sodium fluoride and ammonium hydrogen fluoride. The microdisks are bound by up to eighteen faces; six {202̅3} facets on both the top and bottom of the disk and six radial {101̅0} facets around its central band. The overall morphology and particle size can be modified through change of temperature or alcoholic solvent, both of which affect the development of the {101̅0} faces. The photoluminescence properties of doped microdisks, such as down-conversion in the case of β-NaYF4:Eu3+ or up-conversion for β-NaYF4:Yb3+/Er3+, were investigated in detail. The lifetime and emission of the Eu3+ and Er3+ ions appear related to the morphology of the host crystals. This system provides an excellent example in the tuning and optimization of the optical properties of a material through morphological control via facile change of synthetic conditions.

Metal–Organic Derivatives with Fluorinated Ligands as Precursors for Inorganic Nanomaterials

“…Moreover, some rare-earth doped complex fluorides show photoluminescence and find applications in the fields of solidstate lasers, low-intensity IR imaging, NIR quantum counting devices, 3D flat-panel displays, and biological labels. 516,517 For example, sodium yttrium tetrafluoride (NaYF 4 ) as a very efficient host matrix for NIR-to-visible light upconversion has been the subject of special consideration. High-quality α-and/ or β-phase NaYF 4 :Yb,Er(Tm) nanocrystals (NCs) were prepared using Na-TFA and [Ln(TFA) 3 (H 2 O) x ] in the presence of various coordinating ligands to control the sizes of NCs with high up-conversion luminescence.…”

Fabrication of Au-Ag nanocage@NaYF4@NaYF4:Yb,Er Core-Shell Hybrid and its Tunable Upconversion Enhancement

“…Ag-nanocube@NaYF 4 @NaYF 4 :Yb,Er were synthesized by the fluorination through dissolving the NaF and NH 4 HF 2 in above Ag nanocube@Y(OH)NO 3 · H 2 O@Y(OH)NO 3 · H 2 O: Yb,Er solution under the hydrothermal condition at 180 °C (Fig. 1(e))33. At last, Au-Ag nanocage@NaYF 4 @NaYF 4 :Yb,Er structures were prepared based on the galvanic replacement reaction between the silver nanocubes and HAuCl 4 solution34.…”

Rare-earth doped LaF3 hollow hexagonal nanoplates: hydrothermal synthesis and photoluminescence properties

“…This is different from the course of evolution of hexagonal NaYF 4 NCs obtained from commercial Y 2 O 3 by an in situ ion exchange process without the changes on the size and morphology. 36 When the time is further increased to 12 h, the pure hexagonal phase Based on the time-controlled experiment, the specific mechanism of morphology control of LaF 3 NCs can now be further addressed as depicted in Scheme 1. At low pH value, many primary LaF 3 monomers aggregate to particles without a preferential growth orientation, resulting in an irregular shape under hydrothermal conditions.…”