Monodisperse Octahedral α-MnS and MnO Nanoparticles by the Decomposition of Manganese Oleate in the Presence of Sulfur

Abstract

Octahedral monodisperse R-MnS and MnO nanoparticles have been synthesized by decomposing manganese oleate and elemental sulfur in octadecene at high (250-320 °C) temperature. The chemical composition of the obtained NPs depends on the Mn:S ratio in an unexpected way. Pure R-MnS NP samples are obtained when S:Mn g 2:1, whereas pure MnO NPs require S:Mn e 0.6. Variation of several parameters (concentration of sulfur, heating rate and aging temperature and time) resulted in a R-MnS NP size interval of 11-14 (from Mn monooleate) and 18-30 nm (from Mn dioleate). For MnO NPs only, size control is also possible by addition of free oleic acid (14-24 nm). Analysis of TEM tilting experiments and electron diffraction shows that both R-MnS and MnO nanoparticles have octahedral shape and spontaneously form ordered arrays with strong texture in the {111} direction. Measurement of the magnetic properties showed that R-MnS nanoparticles consist of an antiferromagnetic core and a ferromagnetic-like shell that are exchange coupled below the blocking temperature of the shell (23 K for 29 nm R-MnS NP).

Direct Preparation of Sulfide Semiconductor Nanoparticles from the Corresponding Bulk Powders in an Ionic Liquid

“…The precipitated nanoparticles could be analyzed by powder X‐ray diffraction, which confirmed the structures for all four cases included in Figure 2 (see the Supporting Information for details), face‐centered cubic structure for ZnS, hexagonal for CdS, octahedrical for PbS, and cubic for MnS nanoparticles; these findings match diffraction patterns previously reported in the literature for these types of nanoparticles 15d. 16 Redispersion of the nanoparticles in toluene was carried out to prepare grids suitable for analysis by transmission electron microscopy (TEM).…”

Shape Matters: Anisotropy of the Morphology of Inorganic Colloidal Particles – Synthesis and Function

“…From cubic particles with exclusively [100] surfaces to octahedra with [111] surfaces, different morphologies have been achieved successfully. Large interest exists also in the shape control of other oxidic materials, in particular those with special magnetic, electrochemical, or catalytic properties such as spinels M II O·Fe 2 O 3 (M = Fe, Co, Ni, Mn),125 Mn 3 O 4 ,126 MnO 2 ,127 MnO,128 SnO 2 ,129 In 2 O 3 ,130 Ag 2 O,131 V 2 O 5 ,132 or MgO 133. The previous considerations can be transferred to many more systems 134…”

An Investigation into the Charge‐Storage Mechanism of MnO@Graphite as Anode for Lithium‐Ion Batteries at Low Temperature

“…The synthesis process of MnO@Graphite via solvothermal method was illustrated in Figure . Amorphous MnO x @Graphite was processed in oleic acid to yield Mn‐oleate micelle@Graphite ,. During the process, MnO x was dissolved to yield manganese oleate.…”

“…Amorphous MnO x @Graphite was processed in oleic acid to yield Mn-oleate micelle@Graphite. [9,10] During the process, MnO x was dissolved to yield manganese oleate. At this point, Mn 2 + could intercalate into interlayers of graphite due to its small ion radius of 0.80 Å, [11] similar to Fe 3 + (0.79 Å) generally accepted as a strong graphite intercalation agent.…”