Crystal Phase Control of Luminescing α‐NaGdF₄:Eu³⁺and β‐NaGdF₄:Eu³⁺ Nanocrystals

Abstract

NaGdF4:Eu3+, NaEuF4, and NaGdF4 nanocrystals were synthesized in the high‐boiling coordinating solvent N‐(2‐hydroxyethyl)‐ethylenediamine (HEEDA). Phase pure nanomaterials, crystallizing either in the cubic α‐phase or the hexagonal β‐phase, were obtained by adjusting one reaction parameter only, i.e., the molar ratio between metal and fluoride ions in the synthesis. The hexagonal β‐phase is formed, if this molar ratio is close to stoichiometric, whereas the cubic α‐phase is obtained in the presence of excess metal ions. The optical properties of the Eu3+ doped samples are different for the two crystal phases. The results indicate an increased number of oxygen impurities close to Eu3+ ions, if excess metal ions are used in the synthesis.

Synthesis of biocompatible and luminescent NaGdF4:Yb,Er@Carbon nanoparticles in water-in-oil microemulsion

“…8,9 Among various host materials for lanthanide-doped UCNs, NaGdF 4 nanocrystals are attractive because of the low photo energy associated with high upconversion efficiency. 10,11 At the same time, Gd 3+ ions possess a large number of unpaired electrons, and thus NaGdF 4 nanocrystals can also serve as solid-state contrast agents in magnetic resonance imaging (MRI). 12,13 Therefore, synthesis of high-quality and biocompatible NaGdF 4 nanoparticles may support the development of multimodal bioimaging nanoplatform for diagnosis, detection, and therapy in future bionanotechnology.…”

“…[10][11][12][13] To harness these hydrophobic nanocrystals to biological fields, surface modification is demanded to make them water dispersible, biocompatible, and capable of conjugating to various biomolecules. Zhou et al have used an organic route to convert hydrophobic NaGdF 4 nanocrystals to its hydrophilic analogs by directly oxidizing the surfactants.…”

Synthesis and photoluminescence of highly enhanced green-emitting LaNbTiO6:xEr3+, yBi3+ micro/nanophosphors

“…Recently, there have been considerable efforts in the development of highly efficient and stable light-emissive inorganic micro/ nanomaterials for application in display or lighting devices [1,2]. A particular emphasis has been placed on the research of novel host and phosphor materials with improved luminescent properties for white light emitting diodes (LEDs) because of their prominent and valuable contributions for solid state illumination engineering that must replace traditional incandescent and fluorescent lamps in future [3,4].…”

Europium fluoride based luminescent materials: From hydrogels to porous cryogels, and crystalline NaEuF4 and EuF3 micro/nanostructures

“…Due to the low molar extinction coefficient of the forbidden lanthanide f-f transitions [5][6][7], direct excitation of the lanthanide ions is inefficient, and it has been a common synthetic strategy to incorporate them into host matrices [5,[8][9][10][11][12]. A uniform distribution of the optically active lanthanide ions in the host matrix is an important pre-requisite to achieve efficient luminescence [13].…”