Morphology- and size-dependent spectroscopic properties of Eu3+-doped Gd2O3 colloidal nanocrystals

Abstract

The synthesis, morphological characterization, and optical properties of colloidal, Eu(III) doped Gd2O3 nanoparticles with different sizes and shapes are presented. Utilizing wet chemical techniques and various synthesis routes, we were able to obtain spherical, nanodisk, nanotripod, and nanotriangle-like morphology of Gd2O3:Eu3+ nanoparticles. Various concentrations of Eu3+ ions in the crystal matrix of the nanoparticles were tested in order to establish the levels at which the concentration quenching effect is negligible. Based on the luminescence spectra, luminescence lifetimes and optical parameters, which were calculated using the simplified Judd–Ofelt theory, correlations between the Gd2O3 nanoparticles morphology and Eu3+ ions luminescence were established, and allowed to predict the theoretical maximum quantum efficiency to reach from 61 to 98 %. We have also discussed the impact of the crystal structure of Gd2O3 nanoparticles, as well as coordinating environment of luminescent ions located at the surface, on the emission spectra. With the use of a tunable femtosecond laser system and the Z-scan measurement technique, the values of the effective two-photon absorption cross-section in the wavelength range from 550 to 1,200 nm were also calculated. The nonlinear optical measurements revealed maximum multi-photon absorption in the wavelength range from 600 to 750 nm.

Electronic structure, charge transfer, and intrinsic luminescence of gadolinium oxide nanoparticles: Experiment and theory

“…In reality, gadolinium was never found as a pure free metal in nature up to present, so the most common chemical form the gadolinium oxide (Gd 3+ ) is considered. Currently, this oxide is effectively employed in other equally important applications, e.g., magnetic resonance and fluorescence imaging [2], fabrication of the base for Judd-Ofelt high-efficiency luminescent devices [3], doping-modification of thermally treated nanocomposites [4], semi-commercial manufacturing of magnetocaloric materials [5][6], etc. These abundant and promising applications of Gd 2 O 3 appear to be directly linked with its high chemical activity and structural specificity.…”

Nonlinear Optical Properties of Emerging Nano‐ and Microcrystalline Materials

“…wide bandgap (i.e., fully transparent in the visible region) oxides capable of being doped with lanthanide ions and possessing twophoton or multiphoton absorption properties. [106] In particular, a new approach based on 1D YVO 4 NPs for optical probes was demonstrated that utilizes near infrared to visible upconversion through multi-photon induced f-f emission of Eu 3+ doped nanorods. [107] The femtosecond open-aperture Z-scan measurements for undoped and doped YVO 4 demonstrated coexistence of two-and three-photon absorption processes at 650 nm, and four-and five-photon processes at 1300 nm.…”

Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

“…This quenching mechanism is connected with the concentration of the active luminescence cations, and it is therefore known as concentration quenching. It is influenced by the nature of the material, the nature of the dopant and its distribution and by the NP morphology [196,197]. An optimization of the doping level is therefore required in order to obtain the nanophosphor with the highest emission intensity.…”