Electron microprobe analyzer

Pyrite is the most abundant ore mineral. It occurs as euhedral, framboidal, and colloform forms. Abundance of framboidal pyrite increases stratigraphically upwards. Colloform pyrite contains appreciable amounts of As and Cu (Nakata and Shikazono, unpublished), whereas these contents of euhedral and framboidal pyrite are less than the detection limit of an electron microprobe analyzer. Ishizuka and Imai (1998) found that the As content increases toward outer rim and reaches up to 5 wt% in the rim of colloform pyrite from the Fukazawa deposit. 

Scanning patterns and many analytical data obtained by electron-microprobe analyzer reveal that most stannoidite grains are compositionally homogeneous. There is... 

Four samples were similarly selected for the EPMA experiments. The samples were dried and embedded in polished epoxy cylindrical plugs. Backscattered electron (BSE) images as well as elemental maps of As, Fe and Ni (EDS/WDS) were collected using a JEOL 8600 Superprobe electron microprobe analyzer (Dept, of Geological Sciences, University of Saskatchewan). 

Modes of occurrence of the elements in coal can be determined using a variety of procedures. Perhaps the most effective method is the use of scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX). This method can detect and analyze minerals as small as 1 pm in diameter (Figure 14). The SEM-EDX also provides useful information on the textural relationships of the minerals. Other microbeam techniques, such as the electron microprobe analyzer, ion microprobe, laser mass analyzer, and transmission electron microscopy, have also been used to determine modes of occurrence of elements in coal. 

The contents of Si, Al, Ca, Na, and K of clinoptilolite were measured on the polished thin section by the electron microprobe analyzer, using... 

Microscopy of the Chars. The chars were examined by scanning electron microscopy and an electron microprobe analyzer for particle structure, catalyst distribution, and structural changes at the catalyst sites... 

The problem of defining the point at which the coating was completely stripped was also encountered because the absence or presence of the TiC coatings on the steel in the channel was difficult to ascertain by optical microscopy an electron microprobe analyzer attachment to a scanning electron microscope was employed to confirm the stripping off of the coating. 

Two different instruments are available for microanalysis. The electron microprobe analyzer (EMA) uses high electron beam currents to provide elemental analysis of samples, with moderate spatial resolution and low magnification of the sample. The intensity of emitted X-rays from the... 

Before the advent of the SEM (Johari, 1971), several tools, such as the optic microscope, the transmission electron microscope, the electron microprobe analyzer, and X-ray fluorescence, were employed to accomplish partial characterization this information was then combined for a fuller description of materials. Each of these tools has proficiency in one particular aspect and complements the information obtained with other instruments. The information is partial because of the inherent limitations of each method, such as the invariably cumbersome specimen preparation, specialized observation techniques and interpretation of results. 

Analytical electron microscopy (AEM) permits elemental and structural data to be obtained from volumes of catalyst material vastly smaller in size than the pellet or fluidized particle typically used in industrial processes. Figure 1 shows three levels of analysis for catalyst materials. Composite catalyst vehicles in the 0.1 to lOim size range can be chemically analyzed in bulk by techniques such as electron microprobe, XRD, AA, NMR,... 

Because natural stannite contains a considerable amount of zinc, sphalerite contains a considerable amount of iron, and these contents can be easily analyzed using an electron microprobe, a stannite-sphalerite pair is expected to be a useful indicator of formation temperature and sulfur fugacity. 

Selected sphalerite grains (n=15) were mounted and analyzed by electron microprobe. Isotopic analyses of Pb were conducted on galena and sphalerite grains at Carleton University. Sulphur isotope analyses were performed on sphalerite powders at the University of Ottawa. 

Polished thin sections or iron oxides grains polished in epoxy mounts were analyzed using Universite Laval CAMECA SX-100 5-VVDS electron microprobe under a beam of 15 kV at 100 nA, using a range of natural and synthetic standards. After counting over the peak for 20 to 30 sec, background is measured on both sides for 10 sec. These settings yield minimum detection limits (mdl) as low as 20 ppm for elements such as K, Ca, Al, Si, Ti and Mg, 50 ppm for Mn, Cr and V, 200 ppm for Cu,... 

One hundred samples were collected from drillholes, consisting of different lithologies, alteration, and mineralization. Polished thin sections were made from 70 samples of Chehelkureh rocks. Carbonates were analyzed for K, Na, Ca, Mg, Fe, Mn, Pb, Zn, Y and Sr using a JEOL-733 electron microprobe at the University of New Brunswick. An accelerating voltage of 15 kV with a beam current of 30 nA was applied (1pm beam) for a maximum count-time of 30 seconds. 

Optical examination of etched polished surfaces or small particles can often identify compounds or different minerals hy shape, color, optical properties, and the response to various etching attempts. A semi-quantitative elemental analysis can he used for elements with atomic number greater than four by SEM equipped with X-ray fluorescence and various electron detectors. The electron probe microanalyzer and Auer microprobe also provide elemental analysis of small areas. The secondary ion mass spectroscope, laser microprobe mass analyzer, and Raman microprobe analyzer can identify elements, compounds, and molecules. Electron diffraction patterns can be obtained with the TEM to determine which crystalline compounds are present. Ferrography is used for the identification of wear particles in lubricating oils. 

Ultimately, all quantitative analytical methods rely upon standards, whose composition is determined by the classical techniques of wet chemical quantitative analysis. Obviously, the preferred techniques for analyzing art objects are nondestructive, such as x-ray fluorescence, neutron activation, electron microprobe (both dispersive and nondispersive techniques), and so forth. Emission spectrographic analysis is not suit-... 

Fig. 5. Typical weight-fraction detecting limits of electron microprobe X-ray analyzer...

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