Synthesis of Mixed‐Valent Lanthanide Sulfide Nanoparticles

Abstract

In targeting reduced valent lanthanide chalcogenides, we report the first nanoparticle synthesis of the mixedvalent ferromagnets Eu 3 S 4 and EuSm 2 S 4 . Using divalent lanthanide halides with bis(trimethylsilyl)sulfide and oleylamine, we prepared nanoparticles of EuS, Eu 3 S 4 , EuSm 2 S 4 , SmS 1.9 , and Sm 3 S 4 . All nanoparticle phases were identified using powder X-ray diffraction, transmission electron microscopy was used to confirm morphology and nanoparticle size, and magnetic susceptibility measurements for determining the ordering temperatures and valence. The UV/Vis, Raman and X-ray photoelectron spectroscopies for each phase were compared. Surprisingly, the phase is influenced by the halide and the reaction temperature, where EuCl 2 formed EuS while EuI 2 formed Eu 3 S 4 , highlighting the role of kinetics in phase stabilization. Interestingly, at lower temperatures EuI 2 initially forms EuS, and converts over time to Eu 3 S 4 .

Ultra-mild synthesis of nanometric metal chalcogenides using organyl chalcogenide precursors

“…5b). 95 The authors attributed a combination of high reactivity of (Me 3 Si) 2 S and use of low-valent metal halides as a key to stabilize the mixed-valent phases. The fact that only EuI 2 afforded phase-pure Eu 3 S 4 (the use of EuCl 2 gave EuS NPs whereas EuBr 2 yielded contaminarted sample) highlights the influence of choice of reagent and the role of kinetics in phase stabilization.…”

The Influence of Yb Doping and Sintering Conditions on the Magnetocaloric and Mechanical Properties of EuS

“…Concerning the preparation of EuS, the current research is focused on the wet chemical synthesis of EuS nanoparticles [ 16 , 17 ] or the preparation of EuS films [ 15 ]. EuS nanoparticles have been synthesized by the thermolysis and colloidal routes and by the decomposition of single-source precursors [ 18 ].…”