Regenerable magnetic octahedral layer catalyst for gaseous UPOPs removal

2014 ◽  
Vol 280 ◽  
pp. 627-635 ◽  
Author(s):  
Yang Yang ◽  
Jun Huang ◽  
Shuzhen Zhang ◽  
Siwen Wang ◽  
Shubo Deng ◽  
...  
Keyword(s):  
Octahedral Layer

Mechanochemical Activation of Polymetallic Ore and Further Selective Floatation

2020 ◽  
Vol 844 ◽  
pp. 65-76
Author(s):  
Olena Svietkina ◽  
Kostiantyn Bas ◽  
Jamil Haddad ◽  
Kyrylo Ziborov ◽  
Valentyna Olishevska
Keyword(s):  
Interlayer Space ◽  
Mechanochemical Activation ◽  
Process Intensification ◽  
Raw Material ◽  
Octahedral Layer ◽  
First Case ◽  
Loose Packing ◽  
Elementary Constituent ◽  
Chlorhydric Acid ◽  
Polymetallic Ore

It has been demonstrated that shock-vibrating activation of minerals is a prospective method to impact the ore; it may be used to intensify chemical and physical-chemical processes of mineral raw material processing and preparation. Differences in the composition and phase properties, obtained both in terms of continuous and periodic modes, are in the fact that in the first case loadings deal with interlayer space preserving layered nature of the mineral. When the mode is continuous, then the disturbances cover the octahedral layer though elementary constituent – tetrahedrons – are preserved. It has emerged that the most important advantage of high reacting capability of activated minerals is in the fact that leaching of some ores may be performed in chlorhydric acid at the expense of transformation of some silicate components into a specific state – loose packing of basic silicate chain. Consequently, shock-vibrating activation has become a basis to develop a method of leaching process intensification as well as a method to control phase formation.

A refinement of the dickite structure and some remarks on polymorphism in kaolin minerals

1961 ◽  
Vol 32 (252) ◽  
pp. 683-704 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Crystal Structure ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Structural Features ◽  
Mirror Image ◽  
Hydrogen Atoms ◽  
Octahedral Layer ◽  
Layer Structures ◽  
Infrared Absorption Spectra ◽  
Interlayer Bonding

SummaryThe crystal structure of the clay mineral dickite (Al2Si2H4O9) has been refined to a greater accuracy than that reported in an earlier analysis. Improved lattiçe parameters are: a 5·15±0·001, b 8·940±0·001, c 14·424 ± 0·002Å., β 96° 44′± 1′. The dickite structure shows several significant distortions from the geometry of the idealized kaolin layer, including deformation and rotation of the silica tetra-hedra. The most striking features of the octahedral layer are the extremely short shared edges of 2·37 Å. Although the analysis was not sufficiently accurate to position the hydrogen atoms with certainty, a model consistent with the infrared absorption spectra is proposed. The stacking sequences of kaolin-layer minerals have been considered with reference to the structural features observed in dickite. There are thirty-six ways of superposing two kaolin layers commensurate with the OH-O bonds found in kaolinite, dickite, and nacrite. The twelve sequences showing the least amount of cation-cation superposition between consecutive kaolin layers can be used to construct two one-layer cells, kaolinite and its mirror image, and twelve two-layer cells, including dickite and nacrite. The distortions of the kaolin layer introduce secondary variations in the interlayer bonding that suggest that dickite and nacrite are the most stable of the kaolin layer structures, since they possess the shortest oxygen-hydroxyl contacts.

Atomic Structures of Oxygen-associated Defects in Sintered Aluminum Nitride Ceramics

1999 ◽  
Vol 5 (5) ◽  
pp. 352-357 ◽  
Author(s):  
Yanfa Yan ◽  
S. J. Pennycook ◽  
M. Terauchi ◽  
M. Tanaka
Keyword(s):  
Stacking Sequence ◽  
Contrast Imaging ◽  
Octahedral Layer ◽  
Atomic Structures ◽  
Inversion Domain ◽  
Sintered Aluminum ◽  
Domain Boundaries ◽  
Convergent Beam ◽  
Z Contrast ◽  
Inversion Domain Boundaries

Convergent-beam electron diffraction and Z-contrast imaging are used to study oxygen-associated defects, flat inversion domain boundaries, dislocations, and interfaces in sintered AlN ceramics. The structures of these defects are directly derived from atomic-resolution Z-contrast images. The flat inversion domain boundaries contain a single Al-O octahedral layer and have a stacking sequence of . . .bAaB-bAc-CaAc. . , where -cAb- indicates the single octahedral layer. The expansion at the flat inversion domain boundaries is measured to be 0.06 (±0.02) nm. The interfaces between 2H- and polytypoid-AlN are found to be also inversion domain boundaries but their stacking sequence differs from that of the flat inversion domain boundaries.

Effect of Doping Metal Ions on the Structure Transformation of Octahedral Layer Structure Manganese Oxide

2015 ◽  
Vol 723 ◽  
pp. 670-673
Author(s):  
Chen Liang Zhou ◽  
Bin Zheng Fang ◽  
Jian Wei Cao ◽  
Na Zhang ◽  
Jia Li Han ◽  
...  
Keyword(s):  
Metal Ions ◽  
Manganese Oxide ◽  
Powder Diffraction ◽  
Redox Reactions ◽  
Manganese Oxides ◽  
Layer Structure ◽  
Structure Transformation ◽  
Octahedral Layer ◽  
X Ray ◽  
Before And After

The Octahedral layer structure manganese oxides (Buserite and Birnessite) have been synthesized and modified by aging a MnOx gel which was produced from the redox reactions between Mn2+ and MnO4- in the presence of other metal cations (Mg2+, Ni2+, Co2+ or Cu2+). The present study investigates the structure transformation between Buserite and Birnessite using X-ray powder diffraction conducted on cation doped manganese oxides at different stages of before and after hydration. The results indicate that introduction of Mg2+ into the interlayer can completely achieve the structure transformation between Birnessite and Buserite after hydrated at 24h, and Ni2+ can partially reverse.

Evidence for loss of protons and octahedral iron from oxidized biotites and vermiculites

1971 ◽  
Vol 38 (294) ◽  
pp. 121-137 ◽  
Author(s):  
V. C. Farmer ◽  
J. D. Russell ◽  
W. J. McHardy ◽  
A. C. D. Newman ◽  
J. L. Ahlrichs ◽  
...  
Keyword(s):  
High Refractive Index ◽  
X Ray Diffraction ◽  
Ferric Ions ◽  
Ferrous Ions ◽  
Octahedral Layer ◽  
Irreversible Loss ◽  
X Ray ◽  
External Phase ◽  
Infra Red ◽  
Oxide Ions

SummaryInfra-red examination of a weathered biotite and of biotites that have been converted to vermiculites and subsequently oxidized, indicates that oxidation of octahedral ferrous ions to ferric ions is associated with a reversible conversion of hydroxyl ions to oxide ions. Subsequently, in high-iron biotites, there is an irreversible loss of ferric ions from the octahedral layer, resulting in an increased number of dioctahedral sites. Electron microscopy and X-ray diffraction indicate that ejected ferric ions form either amorphous interlayer oxides or, when bromine is used as an oxidant, a crystalline external phase of β-FeOOH. The high refractive index of some oxidized vermiculites is shown to be due largely to submicroscopic iron oxides.

On Li-bearing micas: estimating Li from electron microprobe analyses and an improved diagram for graphical representation

1997 ◽  
Vol 61 (409) ◽  
pp. 809-834 ◽  
Author(s):  
Gerhard Tischendorf ◽  
Bärbel Gottesmann ◽  
Hans-Jürgen Förster ◽  
Robert B. Trumbull
Keyword(s):  
Electron Microprobe ◽  
Graphical Representation ◽  
Site Occupancy ◽  
Essential Element ◽  
Regression Equations ◽  
Two Dimensional ◽  
Octahedral Layer ◽  
Empirical Relationships ◽  
Free Mica ◽  
Scientific Rationale

AbstractLithium may constitute an essential element in micas, yet it cannot be detected by the electron microprobe. Since Li is critical for correctly classifying micas and properly calculating their formulae, several methods have been proposed to overcome this analytical deficiency. We offer empirical relationships between Li2O and SiO2, MgO, F, and Rb in trioctahedral micas, and between Li2O and F as well as Rb in dioctahedral micas. The resultant regression equations enable lithium contents to be sufficiently well estimated from EPM analyses within the range of validity discussed.Secondly, we introduce an easy to handle, new diagram with the axis variables [Mg-Li] and [Fetot + Mn + Ti-AlVI] for graphical representation and discuss its scientific rationale. Being based on absolute abundances of cations in the octahedral layer, the diagram provides a simple means to classify micas in terms of composition and octahedral site occupancy, and it also allows compositional relationships between Li-bearing and Li-free mica varieties as well as between trioctahedral and dioctahedral micas to be displayed on a single, two-dimensional diagram.

Some properties of clay-water dispersions

1984 ◽  
Vol 311 (1517) ◽  
pp. 353-368 ◽  
Keyword(s):  
Surface Area ◽  
Large Surface Area ◽  
Isomorphous Substitution ◽  
Octahedral Layer ◽  
Sodium Potassium ◽  
Bulk Properties ◽  
Aqueous Dispersions ◽  
Counter Ions

The bulk properties of clay-water dispersions, particularly with montmorillonites, depend on the very large surface area of the materials and their plate-like form. Owing to isomorphous substitution in the clay lattice the plates are charged and hence interact electrostatically with each other. The form of the interaction was tested using macroscopic clay surfaces in the form of cleaved mica and the results compared with those obtained by compression of concentrated aqueous dispersions of various montmorillonites in a homoionic form. The results obtained with mica and lithium montmorillonite were comparable suggesting the latter disperses as single plates. When sodium, potassium and caesium were used as the counter-ions for montmorillonite, differences were observed which were attributed to face-face association. The consequences of isomorphous substitution in either the tetrahedral or the octahedral layer were also examined.

Significance of recent structure determinations of layer silicates for clay studies

Clay Minerals ◽  
1965 ◽  
Vol 6 (2) ◽  
pp. 73-82 ◽  
Author(s):  
G. Brown
Keyword(s):  
Crystal Structures ◽  
Composite Layer ◽  
Silicate Layer ◽  
Layer Silicate ◽  
Octahedral Layer ◽  
Layer Silicates ◽  
Geometrical Features ◽  
Classical Studies ◽  
Structure Determinations ◽  
Tetrahedral Layer

In the last 10 years or so much work has been done to determine the crystal structures of layer silicates more precisely than previously and, as a result, ideas about these structures have had to be revised.Around 1930 the classical studies of Bragg and his collaborators, and of Pauling, established the general geometrical features of layer silicate structures. The basic building units were found to be layers of linked tetrahedra articulated, by sharing oxygens, with layers of octahedra. In the 1 : 1, kaolinite type materials, with layer thicknesses about 7 Å, the composite layer unit was made up of one tetrahedral layer and one octahedral layer; in the mica and chlorite minerals the silicate layer was formed by joining two tetrahedral layers, one on either side, to an octahedral layer.

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