abstract
Systematic shape evolution of hexagonal NiSe crystals is realized via a simple solvothermal route in a
mixture of NiCl26H2O, elemental selenium, hydrazine hydrate and ethylenediamine. By introducing
ammonium chloride as electrolyte and varying the volume ratios of hydrazine hydrate to ethylenediamine, shape evolution of hexagonal NiSe crystals from small hexagonal microdisks to hexagonal
microdisks in larger width, microspheres, hexagonal prisms and hexagonal bitowers is successfully
achieved. X-ray powder diffraction, field emission scanning electron microscopy, energy dispersion
spectrometer, transmission electron microscopy and selected area electron diffraction are performed
for the analyses of the products. The ionization and hydrolysis of ammonium chloride decrease the
nucleation rate of hexagonal NiSe and the diffusion rate of growth resources, while the adsorption of
ethylenediamine at {001} facets of hexagonal NiSe crystals inhibits the crystal growth in o0014
directions, thus leading to various novel architectures