Morphology and Photoluminescence of HfO₂ Obtained by Microwave-Hydrothermal

In this letter, we report on the obtention of hafnium oxide (HfO₂) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV-vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO₂ nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission).