HYDROTHERMAL-ASSISTED SYNTHESIS AND PHOTOLUMINESCENCE OF ZnO MICRORODS

Zinc oxide microrods were grown on Zn foils by a simple hydrothermal method. The XRD and SEM experimental results revealed the dense microrod-like wurtzite ZnO structure grown on Zn foils. The photoluminescence (PL) spectra at room temperature were measured. ZnO microrods exhibit photoluminescence broad emission at 500-650 nm using an excitation wavelength of 215 nm. By Gaussian analysis, the emission shows a maximum intensity at about 540 nm and a shoulder peak at around 570 nm which correspond to interstitial oxygen [O i -

Morphology and Photoluminescence of HfO2Obtained 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 HfO2nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission)

Hydrothermal synthesis of monoclinic WO3 nanoplates and nanorods used as an electrocatalyst for hydrogen evolution reactions from water

Monoclinic WO3 (m-WO3) nanoplates and nanorods were successfully synthesized by a simple hydrothermal process using sodium tungstate dihydrate (Na2WO4 2H(2)O) ammonium nitrate (NH4NO3) and polyethylene glycol (PEG) as initial precursors Phase morphologies and electrochemical properties of the products were characterized by X-ray diffraction (XRD) scanning and transmission electron microscopy (SEM TEM) high-resolution transmission electron microscopy (HRTEM) cyclic voltammetry (CV) and linear sweep voltammetry (LSV) The effect of NH4NO3 concentration on the formation of the pure phase of m-WO3 nanomaterial was studied The product synthesized under NH4NO3-free condition was pure orthorhombic WO3 0 33H(2)O (o-WO3 0 33H(2)O) phase By adding and increasing the amount of NH4NO3 to the solution m-WO3 phase started to form and became pure m-WO3 phase when 1 50 g NH4NO3 was used The morphology of m-WO3 was nanoplates and became nanorods by PEG adding The nanostructured m-WO3 showed much higher electrocatalytic activity for hydrogen evolution from water than that of the commercial bulk m-WO3 including the m-WO3 nanorods with slightly better than the m-WO3 nanoplates (C) 2010 Elsevier B V All rights reservedX1152sciescopu

Corrosion of chromium containing alloys in non-steady state environments containing oxygen, carbon, and chlorine

Internal attack of chromium containing alloys in mixed oxygen-chlorine environments occurs by the formation of pores which penetrate down grain boundaries of the alloys. No internal attack was detected in a binary Fe-20 %Cr alloy at 1200 K in environments containing 2500 ppm Cl2. The rate of internal attack of alloy 800H in such environments was increased by replacing the O2 in the gas by CO2. In mixed oxygen-carbon-chlorine environments, the internal attack occurs by selective chlorination of chromium carbides which precipitate along the grain boundaries