Structural, Spectroscopic, and Magnetic Properties
of Eu<sup>3+</sup>-Doped GdVO<sub>4</sub> Nanocrystals Synthesized
by a Hydrothermal Method
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Abstract
New interesting aspects
of the spectroscopic properties, magnetism, and method of synthesis
of gadolinium orthovanadates doped with Eu<sup>3+</sup> ions are discussed.
Gd<sub>1–<i>x</i></sub>Eu<sub><i>x</i></sub>VO<sub>4</sub> (<i>x</i> = 0, 0.05, 0.2) bifunctional luminescent
materials with complex magnetic properties were synthesized by a microwave-assisted
hydrothermal method. Products were formed in situ without previous
precipitation. The crystal structures and morphologies of the obtained
nanomaterials were analyzed by X-ray diffraction and transmission
and scanning electron microscopy. Crystallographic data were analyzed
using Rietveld refinement. The products obtained were nanocrystalline
with average grain sizes of 70–80 nm. The qualitative and quantitative
elemental composition as well as mapping of the nanocrystals was proved
using energy-dispersive X-ray spectroscopy. The spectroscopic properties
of red-emitting nanophosphors were characterized by their excitation
and emission spectra and luminescence decays. Magnetic measurements
were performed by means of vibrating sample magnetometry. GdVO<sub>4</sub> and Gd<sub>0.8</sub>Eu<sub>0.2</sub>VO<sub>4</sub> exhibited
paramagnetic behavior with a weak influence of antiferromagnetic couplings
between rare-earth ions. In the substituted sample, an additional
magnetic contribution connected with the population of low-lying excited
states of europium was observed
