Manganese chalcogenides exhibit a variety of important magneto-optical properties that collectively result from their crystal structures, the large number of unpaired electrons in high-spin Mn 2+ , bandgaps that span visible to ultraviolet wavelengths, and interesting magnetic ordering schemes. [1] In particular, manganese selenide (MnSe) is an intensively studied antiferromagnetic semiconductor with interesting magnetic ordering behavior, especially as a component in thin-film superlattices where the type of magnetic ordering can be tuned with strain, dimensionality, and film thickness. [2] Solid solutions of manganese-doped ZnSe, for example, permit tuning of the coupled electronic, optical, and magnetic properties, [3] and MnSe is the x = 1 end member of the solid solution of the magnetic semiconductor Zn 1Àx Mn x Se. [4] MnSe is most stable in the octahedrally coordinated rocksalt (RS) structure type, [5] and a number of studies have focused on the synthesis and properties of this polymorph as bulk powders, [6] thin films, [7] and nanostructured solids. [8] The tetrahedrally coordinated non-equilibrium zincblende (ZB) and wurtzite (WZ) polymorphs are extremely rare, yet are of interest because of their direct structural compatibility with III/V, II/ VI, and related semiconductor systems. It has been reported that Zn 1Àx Mn x Se adopts the ZB structure for 0 < x < 0.30 and the WZ structure for 0.30 < x < 0.57. [3] ZB-type MnSe has been stabilized as epitaxial films on ZB-type ZnSe and GaAs substrates, [9] and impure powders have been made by a gasphase precipitation reaction. [10] WZ-type MnSe is known to be highly unstable, [5] and has only been observed as minor impurity phases. [10] The inability to isolate nominally phasepure, bulk-scale quantities of the non-equilibrium tetrahedrally bonded polymorphs of MnSe, particularly the elusive WZ polymorph, precludes some detailed studies of their properties and structures and represents a significant gap in this important family of magnetic semiconductors.
Herein we report a colloidal synthesis route to WZ-type MnSe (g-MnSe), which forms as solution-dispersible nano-Ocean Optics HR4000 high-resolution spectrometer with a Micropack DH-2000 BAL UV-Vis NIR light source. Nanoparticle samples were diluted with ethanol for collection of UV/vis data. A control reaction, performed by heating the solvent and stabilizers using the same temperature profile as the reaction used to make WZ-type MnSe, was used as the background for the UV/visible absorption measurement.