ZnO microspheres: Controllable preparation and optical properties

• The ZnO microsphere is prepared for first time.
• The ZnO microsphere is prepared through a template-free hydrothermal method.
• The ZnO microsphere we prepared is monodisperse.

Micrometer-sized ZnO spheres with average diameter about 2 μm were prepared through a facile template-free hydrothermal method. Their structures and morphologies were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). XRD result indicates that the sample is pure hexagonal ZnO with a crystalline zincite structure. The FESEM images confirmed that the samples were monodisperse ZnO microspheres. Optical properties have been investigated by using UV–vis absorption spectrum and photoluminescence measurement. The UV–vis absorption spectrum displays an obvious and significant absorption at wavelength less than 400 nm. Photoluminescence measurement was tested at excitation wavelength of 325 nm. From the luminescence spectrum, we can observe that the ZnO microspheres show strong emission feature at 400 nm and a blue emission at 461 nm.

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