Anisotropic morphology, formation mechanisms, and fluorescence properties of zirconia nanocrystals

ZrO₂ nanocrystals with spheres and elongated platelets were systemically prepared through a simple hydrothermal method by the use of ZrOCl₂·8H₂O and CH₃COOK as raw materials. The anisotropic morphology and formation mechanism of the monoclinic and/or tetragonal ZrO₂ were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, and high-resolution transmission electron microscope techniques. The uniform elongated platelets and star-like structures were composed of short nanorods with a diameter of approximately 5 nm and a length of approximately 10 nm. The different morphologies were formed due to the different contents of CH₃COO^- and Cl^- and their synergy. The fluorescence band position and the band shape remained about the same for excitation wavelengths below 290 nm and the different morphologies of the nanocrystals.