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.

New data on georgiadesite

1983 ◽  
Vol 47 (343) ◽  
pp. 219-220 ◽  
Author(s):  
Roland C. Rouse ◽  
Pete J. Dunn
Keyword(s):  
Single Crystal ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
X Ray

AbstractThe chemistry and crystallography of type georgiadesite from Laurion, Greece, have been reexamined using electron microprobe analysis along with powder and single-crystal X-ray diffraction. Georgiadesite is monoclinic, P21/c, with a = 13.803(10), b = 7.910(2), c = 10.812(4) Å, and β = 102.68(3)°. No twinning was observed. The probable chemical formula is either Pb16(AsO4)4Cl14O2(OH)2 or Pb16(AsO4)4Cl14(OH)6. The calculated densities for these formulae are 6.39 and 6.44 g/cm3, respectively, compared to a measured value of 6.3 + 0.3 g/cm3

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.

Pseudomesolite is mesolite

1985 ◽  
Vol 49 (350) ◽  
pp. 103-105 ◽  
Author(s):  
Rab Nawaz ◽  
John F. Malone ◽  
Victor K. Din
Keyword(s):  
Chemical Analysis ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
X Ray ◽  
Unit Cells ◽  
Wet Chemical

AbstractPseudomesolite from Carlton Peak, described by Winchell (1900), is shown to be mesolite by means of chemical and X-ray data. A proposal to this effect has been accepted by the International Mineralogical Association's Commission on New Minerals and Mineral Names. Electron microprobe analysis revealed variations in the composition of pseudomesolite and showed the presence of faroelite. The X-ray powder diffraction pattern is similar to that of mesolite. Single-crystal Weissenberg photographs showed a twinning intergrowth which is explained by a 90° rotation of 50% of the unit cells about the c-axis, so that the a- and b-axes of rotated cells coincide with the b- and a-axes respectively of the unrotated cells. This twinning can not be detected optically. Mesolite has recently been proved to be orthorhombic, contrary to the long-held view that it is monoclinic.Pseudomesolite from Oregon is also shown to be mesolite by single crystal Weissenberg photographs. A wet chemical analysis shows this material to be extremely silica-rich.

SYNTHESIS OF COMPOSITE POWDERS «TIC – NICRBSI ALLOY BINDER» FOR CLADDING AND DEPOSITION OF WEAR-RESISTANT COATINGS

2018 ◽  
pp. 43-53 ◽  
Author(s):  
G. A. Pribytkov ◽  
I. A. Firsina ◽  
V. V. Korzhova ◽  
M. G. Krinitсyn ◽  
A. A. Polyanskaya
Keyword(s):  
Titanium Carbide ◽  
Electron Microprobe ◽  
Composite Powder ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Binder ◽  
Carbide Inclusions

TiC + NiCrBSi binder metal matrix composites were obtained by self-propagating high-temperature synthesis (SHS) in the reaction powder mixtures of titanium, carbon (carbon black) and NiCrBSi alloy. It has been found that steady combustion in a stationary mode occurs when the content of the thermally inert metal binder in reactive mixtures does not exceed 50 vol.%. Porous SHS cakes were crashed and resulting granules were separated to fractions by screening to get the composite powder fraction necessary for coating application. Synthesis products were studied by optical and scanning electron microscopy, X-ray diffraction and electron microprobe analysis. It has been found that the average size of carbide inclusions depends on the content of thermally inert alloy powder in the reaction mixtures and can be purposefully regulated in a wide range. The microhardness of composite powder granules obtained by crushing the SHS conglomerates decreases monotonically with an increasing content of the metal binder having hardness less than that of titanium carbide. According to X-ray diffraction data, the titanium carbide lattice parameter turns out to be considerably less than values known for equiatomic titanium carbide. It has been found by electron microprobe analysis of carbide inclusions in the composite structure that the ratio of carbon and titanium mass contents is 0,21 as compared with 0,25 in equiatomic titanium carbide. Iron and silicon contents in the carbide are negligible, oxygen and nickel contents are below 1 wt.%, and chromium content is 2,5 wt.%. The analysis of known data on the effect of all the above-listed dopants on the titanium carbide lattice allows for a conclusion that the carbon deficit is a main reason of the lattice parameter reduction.

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