X-ray and electron microscopic analyses

X-ray and electron microscopic analyses are widely used techniques for characterizing catalysts. The papers that follow this introductory chapter will describe the application and utility of these techniques in understanding and developing new and improved catalysts. 

Z Ba(OH)2 These samples were then charged into the reactor under nitrogen, tested, removed from reactor under nitrogen and subject to X-ray powder diffraction analysis. The XPS and electron microscopic analyses were carried out on air-exposed samples. Similar analyses were carried out on untested catalysts. 

The consolidated titanate waste pellets are similar in appearance to their glass counterparts, i.e., both are dense, black and apparently homogeneous. Microscopic analyses, however, reveal important differences between these two waste forms. While little definitive work has been done with glassy waste forms, it is apparent that several readily soluble oxide particulates of various nuclides are simply encapsulated in the glass matrix. The titanate waste form has undergone extensive analyses which includes optical microscopy, x-ray, scanning electron microscopy, microprobe, and transmission electron microscopy (l ) The samples of titanate examined were prepared by pressure sintering and consisted of material from a fully loaded titanate column. Zeolite and silicon additions were also present in the samples. 

The effectiveness of mechanical separation and the verification of binder purity have been proved by X-ray diffraction. Scanning Electron Microscope analyses and thermogravimetiic analysis and differential thermal analysis. 

The characteristic feature of solid—solid reactions which controls, to some extent, the methods which can be applied to the investigation of their kinetics, is that the continuation of product formation requires the transportation of one or both reactants to a zone of interaction, perhaps through a coherent barrier layer of the product phase or as a monomolec-ular layer across surfaces. Since diffusion at phase boundaries may occur at temperatures appreciably below those required for bulk diffusion, the initial step in product formation may be rapidly completed on the attainment of reaction temperature. In such systems, there is no initial delay during nucleation and the initial processes, perhaps involving monomolec-ular films, are not readily identified. The subsequent growth of the product phase, the main reaction, is thereafter controlled by the diffusion of one or more species through the barrier layer. Microscopic observation is of little value where the phases present cannot be unambiguously identified and X-ray diffraction techniques are more fruitful. More recently, the considerable potential of electron microprobe analyses has been developed and exploited. 

Characterization. IR spectra of the samples were recorded on Nicolit AVATAR360 spectrometer. The TEM images were obtained on Hitachi H-8100IV electron microscope. TGA and DTA analyses were carried out in Du pont 9900 Thermal Analysis System. X-ray diffraction (XRD) measurement was conducted on a Siemens D5005 diffractometer using Cu Ka radiation (X = 1.54 °A). 

This technique encompasses a large scope of instruments ranging from mobile spectrometers to high resolution spectrometers. On-line analysers and probes that can be fitted to scanning electron microscopes (SEMs) allow instant analyses to be performed (i.e. microanalysis by X-ray emission). 

Kehoe JC. 1984. Intracanal corrosion of a silver cone producing a localized argyria Scanning electron microscope and energy dispersive x-ray analyzer analyses. Journal of Endodontics 10 199-201. 

The present workflow includes two complementary high-throughput characterization methods X-ray diffraction (XRD) for structural information and scanning electron microscope/energy dispersive X-ray (SEM/EDX) analysis for quantitative compositional information. Automated rapid-serial XRD and EDX analyses were performed using programmable xy-stages in combination with suitable software. 

The polished samples are sputtered with a thin layer of gold for analysis in a scanning electron microscope (SEM), a Jeol JSM 35c fitted with a link AN 10000 energy-dispersive X-ray spectrometer (EDS). The fractured surfaces and polished sections through fractured specimens can also be prepared and analysed in this manner. SEM analysis may reveal a non-uniform fibre distribution in the composite. In composites sintered at different temperatures, cracking in the matrix phase and residual porosity can be identified and the filler particles are discernible. The EDS indicates the higher particles and the matrix constituents. 

---