Self-assembled hollow rare earth fluoride alloyed architectures with controlled crystal phase and morphology

Abstract

A general synthetic protocol has been developed to assemble EuF 3 :Ln 3+ and EuF 3 :Ln 3+ /NH 4 + (Ln = Y, Gd, Tb, Dy, Ho, Er, and Tm) alloyed nanocrystallites into hexagon-shaped sub-microcages and hollow sub-microspheres. The structure, morphology and growth kinetics of the alloyed crystallites are investigated. Based on the results obtained by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS), it is proposed that the possible formation mechanisms for EuF 3 :Ln 3+ and EuF 3 :Ln 3+ /NH 4 + (Ln = Y, Gd, Tb, Dy, Ho, Er, and Tm)alloyed architectures involves a crystal-phase-mediated self-assembly process. The crystal structure and morphology are strongly influenced by the Eu/Ln feed molar ratio in the starting solution. A higher feed ratio of Eu to Ln facilitates the growth of hexagonal EuF 3 :Ln 3+ (Ln = Y, Gd, Tb, Dy, Ho, Er, and Tm) alloyed crystallites and results in the formation of hexagon-shaped sub-microcages, while a lower feed ratio of Eu to Ln accelerates the growth of cubic NH 4 Ln 3 F 10 :Eu 3+ (Ln = Y, Gd, Tb, Dy, Ho, Er, and Tm) alloyed crystallites and leads to the assembly of the alloyed nanocrystals into hollow sub-microspheres. Additionally, the as-synthesized alloyed architectures show good performance in highly efficient fluorescent host materials.

Controllable synthesis of NH4Eu3F10nanospheres and application in bioimaging

“…[22][23][24][25] The results resemble those of EuF 3 :Tb 3+ and EuF 3 :Tb 3+ /NH 4 + hollow sub-microstructures we previously reported. 26 The ratio of N, Eu and F detected by XPS is 3.7 : 11.0 : 31.4, which is approximate to the stoichiometric ratio 1 : 3 : 10 of NH 4 Eu 3 F 10 , and further confirms the preparation of NH 4 Eu 3 F 10 .…”

Design of Pb1−xSrxF2 hollow crystals with gas–solution interfacial reactions

“…5 The hollow PbF 2 microspheres were obtained in the presence of CTAB and citric acid, 6 hollow EuF 3 – with the assistance of EDTA and oleic acid, 7 LaF 3 :Yb 3+ /Er 3+ fullerene-like nanoparticles – from La(OH) 3 solid nanospheres by a dissolution-recrystallization process at 200 °C, 8 EuF 3 :Ln 3+ − from EDTA water/ethanol solution during synthesis under hydrothermal conditions. 9 Nevertheless, hollow crystals with a cage-like morphology can also be obtained at low synthesis temperatures under precise control over the crystallization kinetics. For example, a dissolution–regrowth strategy was used to obtain cobalt squarate cages via the ultrasonic treatment.…”

Determination of chromium(III) in aqueous solution using CePO4:Tb3+ nanocrystals in a fluorescence resonance energy transfer system

“…Rare earth phosphate nanocrystals have attracted growing interest for use as luminescent label materials owing to their unique properties, which include long lifetimes, high quantum yields (up to 61%), low photobleaching, expected low toxicity and high chemical stability (26)(27)(28)(29)(30)(31) …”

“…Recent advances in nanotechnology have shown the great promise of nanomaterials in chemical and biological sensor design (22)(23)(24)(25). Rare earth phosphate nanocrystals have attracted growing interest for use as luminescent label materials owing to their unique properties, which include long lifetimes, high quantum yields (up to 61%), low photobleaching, expected low toxicity and high chemical stability (26)(27)(28)(29)(30)(31). Among these lanthanide nanoparticles, CePO 4 :Tb 3+ nanocrystals have been widely studied due to their unique properties (32), for example, their convenient synthesis, water-solubility, ease of dispersal and stable luminescence, and have been applied in determination and sensing.…”