Problems in electron microprobe analysis of the lanthanides: The x-ray lines

1990 ◽  
Vol 48 (2) ◽  
pp. 200-201
Author(s):  
P. F. Hlava
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Atomic Number ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Chemical Behavior ◽  
X Ray ◽  
Lanthanide Series ◽  
Valence Electrons

Electron microprobe analysis of materials that contain the lanthanide series of rare earth elements (REE) in natural abundance ratios presents a difficult and truly unique set of problems due to the their chemical and crystallographic similarity and the complexity of the L-spectra used for analysis. REEs differ from one another by the number of protons in their nuclei and the number of electrons in their second inner shell. There are two series of REEs - the lanthanides, from atomic number 58 through 71 and the actinides from 90 through 103. By convention, when most workers speak of the REEs they refer to the lanthanides plus lanthanum, often yttrium and rarely scandium (because these elements are geochemically associated with the lanthanides proper). The terms REE and lanthanide, when used in this paper, will refer to elements of atomic number 57 through 71. In all of these elements the two outer shells, where the valence electrons reside, are essentially identical resulting in chemical behavior that is also essentially identical.

A Combined Dilution and Line-Overlap Coefficient Solution for the Determination of Rare Earths in Monazite Concentrates

1981 ◽  
Vol 25 ◽  
pp. 133-137
Author(s):  
T. K. Smith
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Atomic Number ◽  
Rare Earths ◽  
Microprobe Analysis ◽  
Matrix Effects ◽  
Emission Spectra ◽  
X Ray ◽  
Overlap Coefficient

The rare earth elements (REE) together give guite complex X-ray emission spectra with a considerable number of overlaps at analytical energies by lines of other REE with lower atomic numbers. Where the concentration of REE is high, as in lanthanide minerals, this Interference is more difficult to rectify. Smith and Gold resolved a similar problem with lower atomic number elements in energy dispersive microprobe analysis by establishing a series of overlap coefficients. They asserted that accurate corrections were necessary because of the relatively poor overall resolution of the instrument and that these should not be limited to the major coincidences. Some of the smaller values had probably been ignored because they were considered statistically Insignificant. The mathematical matrix of Smith and Gold covered 22 elements from fluorine to barium, with intensity coefficients (other than intraelement) quoted from 0.01% to 282.1% and with ZAF corrections necessary in cases of K to L conversion. The overlap coefficients were also adjusted for matrix effects.

A RE-EXAMINATION OF THE RARE-EARTH-ELEMENT ORTHOPHOSPHATE STANDARDS IN USE FOR ELECTRON-MICROPROBE ANALYSIS

2003 ◽  
Vol 41 (1) ◽  
pp. 221-232 ◽  
Author(s):  
J. J. Donovan ◽  
J. M. Hanchar ◽  
P. M. Picolli ◽  
M. D. Schrier ◽  
L. A. Boatner ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Electron Microprobe ◽  
Earth Element ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
The Rare Earth

X-ray Diffraction/Electron Microprobe Analysis of Surface Films Formed on Alloys During Hydrothermal Reaction with Geologic Materials

1984 ◽  
Vol 28 ◽  
pp. 367-375 ◽  
Author(s):  
R. G. Johnston ◽  
M. B. Strope ◽  
R. P. Anantatmula
Keyword(s):  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Hydrothermal Reaction ◽  
Pressure Vessels ◽  
Surface Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Geologic Materials ◽  
Structure Phase

AbstractX-ray diffraction and electron microprobe analysis were used in combination to identify reaction phases that formed on the surfaces of low-carbon steel specimens reacted with a 75% basalt-25% bentonite mixture and anion-doped water in sealed pressure vessels at 100°C and 250°C. Reaction phases on specimen surfaces and in adhering geologic material were identified by conventional X-ray diffraction scans of entire specimens with intact reaction layers. Comparison of results from adhering geologic material and scans of selectively removed layers allowed establishment of approximate reaction gradients in the adhering packing material. Electron microprobe analysis of specimens in cross-section provided quantitative chemical analyses of adhering reaction phases, and identification of reaction layer composition gradients and thicknesses. Magnetite formed on the surface of specimens reacted at 250°C for 4 weeks. Iron-enriched clay was also observed on specimen surfaces and in the adjacent basalt-bentonite mixture. The 100°C experiments yielded surface films of a siderite-structure phase, (Fe,Ca,Mn)CO3, that were not observed in previous experiments with synthetic ground-water. Less extensive iron enrichment of the adjacent clays compared to that seen in the 250°C experiments was observed. The siderite-structure phase generally formed when no carbonate ion was present in the initial solution, implying dissolution of impurity calcite in the bentonite as the controlling factor in the reaction. The results demonstrate the utility of combining X-ray diffraction and electron microprobe analysis for characterization of reaction phases on alloys reacted with complex geologic materials.

Nature of dioctahedral micas in Spanish red soils

Clay Minerals ◽  
1997 ◽  
Vol 32 (1) ◽  
pp. 107-121 ◽  
Author(s):  
J. M. Martin-Garcia ◽  
G. Delgado ◽  
M. Sanchez-Maranon ◽  
J. F. Parraga ◽  
R. Delgado
Keyword(s):  
Powder Diffraction ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
X Ray ◽  
Red Soils ◽  
Mineral Phases ◽  
Composition And Structure ◽  
Structural Formulae ◽  
Coarse Gravel

AbstractStructural formulae and other crystallochemical parameters were used to study different species of dioctahedral micas in clay and coarse gravel fractions of horizons from a red soil (Ultic Haploxeralf) in southern Spain. Mineralogical analyses using X-ray powder diffraction, and measurements of theb0parameter revealed dioctahedral micas, illite and paragonite. Structural formulae established from electron microprobe analysis and energy dispersive X-ray analysis showed the illites to be K mica related in elemental composition and structure to muscovite and phengite. The paragonites were found to be closer to ideal mica. Structural formulae for Na-K dioctahedral micas were obtained with crystallochemical characteristics intermediate between those of Na micas and K micas. The possibilty of these micas representing individual mineral phases or intergrowths of Na and K micas is discussed. In the soil profile, micas from the Bt horizon showed the largest crystallochemical changes induced by pedogenesis.

Monoclinic structure and nonstoichiometry of `KAlSiO4-O1'

2013 ◽  
Vol 69 (4) ◽  
pp. 334-336 ◽  
Author(s):  
Aleksandar Kremenović ◽  
Biljana Lazic ◽  
Hannes Krüger ◽  
Martina Tribus ◽  
Predrag Vulić
Keyword(s):  
Single Crystal ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Derivatives Of ◽  
Aluminium Silicate

Crystals of KAlSiO4-O1(potassium aluminium silicate) were synthesized using a flux method and analysed utilizing single-crystal X-ray diffraction and electron microprobe analysis. Both methods confirm that the crystals are nonstoichiometric according to K1−xAl1−xSi1+xO4withx= 0.04 (1). KAlSiO4-O1is closely related to the stuffed derivatives of tridymite, although the topology of the Si/Al-ordered framework is different. Six-membered rings of UUDDUD and UUUDDD (U = up and D = down; ratio 2:1) configurations are present in layers parallel to theabplane. In contrast, the framework of tridymite exhibits UDUDUD rings. The crystals are affected by inversion, pseudo-orthorhombic and pseudo-hexagonal twinning.

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