Edward P. Fisher

Decomposition of the sulfates of copper, iron (II), iron (III), nickel, and zinc: XPS, SEM, DRIFTS, XRD, and TGA study

The bulk and surface characteristics during decomposition of the transition metal sulfates of copper, iron (II), iron (III), nickel, and zinc are investigated utilizing various spectroscopic techniques. An oxidized form of sulfur was detected on the surface during decomposition of all metal sulfate samples, except zinc sulfate. Surface characteristics were not necessarily representative of the bulk characteristics. Oxy-sulfate was observed with copper sulfate only. Lower decomposition temperatures were observed in vacuum as compared to those at atmospheric pressure. Uniform sulfur distribution was observed across sample cross sections. Analysis consisted of Scanning electron microscopy/X-ray microanalysis, X-ray photoelectron spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis, and X-ray diffraction.

Thermal decomposition of the rare earth sulfates of cerium(III), cerium(IV), lanthanum(III) and samarium(III)

Surface and bulk chemical and elemental composition of the rare earth sulfates of cerium(III), cerium(IV), lanthanum(III) and samarium(III) were characterized during various stages of thermal decomposition. Decomposition was conducted under both vacuum and atmospheric conditions. In situ analysis was conducted on samples decomposed in vacuum. As identified by X-ray diffraction, the bulk decomposition of all the rare earth sulfate samples to their corresponding oxide, in atmosphere, proceeded via the formation of an oxysulfate. For the exception of cerium(III) sulfate, similar results were obtained in thermogravimetric analysis. The thermal decomposition profile, as determined by X-ray microanalysis was similar to that observed in thermogravimetric analysis and X-ray diffraction. Elemental maps revealed no observable concentration gradients of sulfur. Surface composition was not necessarily representative of the bulk composition. Thermal decomposition of sulfates to an oxide initiated at a lower temperature in vacuum than that observed at atmospheric pressure.

Characterization of ceramic hydrogen separation membranes with varying nickel concentrations

Abstract Ceramic hydrogen separation membranes in the stoichiometric form BaCe0.8Y0.2O3, doped with various concentrations of nickel, were characterized by utilizing X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic-force microscopy (AFM). Characterization was performed at room temperature, 550°C and 650°C, and after exposure to hydrogen. Migration of nickel to the surface and changes in both elemental composition and oxidation states were observed at elevated temperatures. The concentration of nickel significantly affects surface morphology and roughness.