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Size-controllable monodisperse nanomaterials have been studied intensively due to their fundamental scientific interest and potential technological applications. [1] So far, the monodisperse magnetic nanocrystals, such as Fe, Co, FePt, CoPt, Fe 2 O 3 , Fe 3 O 4 , have been synthesized [2] for possible applications in magnetic data storage, ferrofluids, refrigeration systems, medical imaging, drug targeting, and catalysis. [3] Compared with a number of works done on these nanomagnetic metals and metal oxides, sparse work on the preparation and magnetic properties of nanoscale magnetic metallic sulfides has been reported so far. The europium monochalcogenides, EuX (X = O, S, Se, Te), with the rock-salt structure have been studied extensively since the 1960s. The pure, bulk EuO and EuS crystals, whose Curie temperatures (T C ) are 69 and 16.6 K, respectively, are well known to be insulating ferromagnets, in which the Heisenberg model applies. [4] Owing to their wide range of potential applications, such as ferromagnetic semiconductors and magnetoresistance, optomagnetic, and luminescent materials, [4,5] renewed attention has been given to the synthesis and properties of EuO and EuS crystals in the past number of decades. In an earlier study, we synthesized magnetic EuS nanoparticles with an average size of 5.5 nm, [5e] but until now little work on the size-controllable synthesis of monodisperse EuS nanocrystals has been reported. Herein, we report a direct and facile method to synthesize monodisperse EuS nanocrystals with sizes ranging from 2.6 to 20 nm. The EuS nanoparticles were prepared by the thermal decomposition of molecular precursors [Eu(phen)(ddtc) 3 ] and [Eu(bpy)-(ddtc) 3 ] (phen = 1,10-phenanthroline; bpy = 2,2'-pyridine; ddtc = diethyldithiocarbamate), in a way similar to previous work. [5d, e] The as-synthesized nanocrystals have been found to show uniform sizes and could be self-assembled into twodimensional (2D) or three-dimensional (3D) ordered superlattices. It is known that the decrease of the crystal size usually affects the properties of magnetic materials, as the small size usually gives rise to new surfaces, which result in a possible quantum tunneling effect and interparticle interactions. [6] The magnetic behavior of monodisperse EuS nanocrystals with controllable particle sizes was investigated. The magnetic properties were observed to depend strongly on particle size, as found in other nanoscale magnetic materials. [7] These results are interesting and helpful for the synthesis of lanthanide sulfides and in systematically understanding the relationship between size and magnetic properties of nanoscale ferromagnetic samples. On the other hand, a better understanding of the size-dependent properties of magnetic nanoparticles will be helpful to elucidate magnetizing mechanisms and to facilitate the design of magnetic materials.The single molecular precursor was prepared in the way reported by Formanovskii et al. [8] with slight modifications (see Supporting Information). The analysis res...

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“…The single molecular precursor was prepared in the way reported by Formanovskii et al 8. with slight modifications (see Supporting Information).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Size‐Dependent Magnetic Properties of Monodisperse EuS Nanocrystals

Zhao

Sun

et al. 2006

Small

110

104

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“…12,13 These NCs were capped with oleylamine and trioctylphosphine. Size and morphology were determined using HRTEM ͑Fig.…”

mentioning

confidence: 99%

Element-specific magnetometry of EuS nanocrystals

Selinsky

Keavney

Bierman

et al. 2009

Applied Physics Letters

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A soft x-ray absorption and x-ray magnetic circular dichroism ͑XMCD͒ study of the ferromagnetism in solution-grown EuS nanocrystals ͑NCs͒ is reported. The absorption edges of Eu M 5 and M 4 , S K, O K, and P K were probed to determine elementally specific contributions to the magnetism of EuS NCs. Differential spin absorption was observed by XMCD at the Eu M 5,4 edges confirming the presence of a magnetic moment on the Eu 2+ 4f shell. No dichroic signal was observed for S, O, or P. Vibrating sample magnetometry of ensembles of NCs shows ferromagnetic properties consistent with the XMCD studies.

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“…It seems interesting to point out that the concurrent attempts to synthesize these precursors from rare-earth nitrates in water (based on Ivanov's work [46]) gave us final products with very poor purity for Sm and Er and turned out to be totally unsuccessful for Tm, Lu and Y. …”

Section: Complex Synthesismentioning

confidence: 99%

“…For this reason, the availability of air-stable S-based rare earth complexes is quite limited. The only serious candidates are the heteroleptic compounds in which the N,N-dialkydithiocarbamate ligand is associated with bidentate nitrogen-donating ligands, in particular [Ln(Et 2 dtc) 3 (phen)] and [Ln(Et 2 dtc) 3 (bipy)] (where Et 2 dtc refers to N,N-diethyldithiocarbamate, phen to 1,10-phenanthroline, and bipy to 2,2 0 -bipyridine), for which the syntheses have already been described in several papers [42][43][44][45][46][47][48][49][50]. These compounds have been successfully used for synthesis of rare earth sulfides [47].…”

Section: Introductionmentioning

confidence: 99%