Characterization of ZnO flowers of hexagonal prisms with planar and hexagonal pyramid tips grown on Zn substrates by a hydrothermal process

Flower-like ZnO crystals on zinc substrates were synthesized by a simple hydrothermal method in different solutions containing 0.05, 0.10, 0.20, 0.30 and 0.40 g LiOH. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) showed that the products were wurtzite hexagonal ZnO flowers, composed of single crystalline hexagonal prisms grown along the [0 0 0 1] direction with planar and hexagonal pyramid tips, including the Zn–O stretching vibration at 411.5 cm−1. Photoluminescence (PL), excited by a 215 nm wavelength at room temperature, exhibited strong green emission at 543 nm.

Schematic diagram for a possible growth mechanism of ZnO hexagonal prisms with planar and hexagonal pyramid tips on Zn substrates.Figure optionsDownload as PowerPoint slideHighlights
► ZnO as a wide band gap semiconductor.
► Different LiOH contents enable us to hydrothermally control its morphologies.
► Its green emission seemed to be associated with oxygen vacancies.
► A promising material for different applications.