Morphology-controlled synthesis of anisotropic wurtzite MnSe nanocrystals: optical and magnetic properties

Manipulating the shape and size of metastable semiconductor nanocrystals (NCs) is important in various applications. In this work, anisotropic tetrapod- and waterdrop-shaped MnSe NCs with wurtzite (WZ) structure have been successfully synthesized by a one-pot solvothermal approach. The morphology, size and crystal structure have been investigated using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and powder X-ray diffraction (XRD). It was found that the shape and aspect ratio of WZ-MnSe NCs can be easily controlled by simply varying the heating rates. Furthermore, these WZ-MnSe NCs display blue–violet emission, which may find applications in full-colour display and short wavelength optoelectronic devices. The magnetic measurements indicate that the Néel temperature is found to be reduced with decreasing nanocrystal diameter. The size-dependent phase-transition behavior is attributed to the surface effect.