Divalent Europium Nanocrystals: Controllable Synthesis, Properties, and Applications

Abstract

Magnetic and luminescent bifunctional divalent europium nanocrystals (Eu(2+) NCs) are a promising class of novel advanced materials that have various applications in magneto-optic devices, catalysis, bioimaging, and solar cells. In the past few decades, much work has been carried out to study the synthesis, properties, and applications of Eu(2+) NCs. The aim of this Minireview is to present the progress in preparing Eu(2+) NCs based on the reported research, by describing the advantages and disadvantages of the synthesis methods. The morphologies and size are controlled through adjusting the experimental conditions. Eu(2+) NCs show superior magnetic and luminescence properties simultaneously. Self-assembly and doping with other ions are important routes to improve their magnetic and luminescence properties. Their applications in magneto-optic devices are discussed. Some difficulties and challenges in the fabrication of Eu(2+) NCs are discussed, such as water-soluble Eu(2+) NCs and tunable luminescence in the whole visible region.

Dithiocarbamate Complexes as Single Source Precursors to Nanoscale Binary, Ternary and Quaternary Metal Sulfides

“…Since 2005, the area has developed significantly, being especially focused on the synthesis of EuS, a narrow band gap (1.65 eV) ferromagnetic semiconductor with a Curie temperature of 16.6 K. A number of reports detail formation of good quality, monodisperse, EuS nanocrystals. , The first was from Stoll and co-workers, who prepared europium complexes, [Eu­(S 2 CNR 2 ) 3 (1,10-phen)] (R = Me, Et, Pr, Bu), and measured their thermal stability by TGA. Each decomposes in a single step between 280 and 350 °C, being independent of the substituents, and heating solid [Eu­(S 2 CNEt 2 ) 3 (1,10-phen)] at 900 °C gave black EuS as shown by PXRD .…”

Solid-State and Nanoparticle Synthesis of EuSxSe1–x Solid Solutions

“…This work also reports the first synthetic route to prepare EuS x Se 1– x alloyed nanoparticles. The synthesis of EuS nanoparticles has been reported by several groups, ,,− while Hasegawa , and others have led the development of EuSe nanoparticles. , The use of the dithiocarbamate ligand as a source for the sulfur component and diphenyl­diselenophosphate for selenium were obvious choices given the demonstrated utility in the syntheses of the end members. However, we discovered these precursors presented challenges to forming alloys across the full composition range due to the differing reactivity of the S and Se precursors.…”

Fluorescence-Magnetism Functional EuS Nanocrystals with Controllable Morphologies for Dual Bioimaging

“…Magnetic resonance imaging (MRI) is one of the most popular techniques in modern clinical diagnosis, as it is able to offer deep tissue penetration, provide admirable three-dimensional soft tissue details, imaging by noninvasive detection. − Nevertheless, the spatial resolution of this technique is not ideal, which enables one to resolve only objects larger than a few micrometers in size and often magnetic hardware (cardiac pacemaker, heart stent, joint replacement, and so forth) is not suitable for MRI online observation during surgery. By contrast, fluorescence imaging (FI) possesses much higher sensitivity and potential application in real-time imaging compared to MRI. , However, the spatial resolution of fluorescence imaging in turbid media and the depth perception are very poor .…”