Combined Near-infrared and X-ray Diffraction Investigation of the Octahedral Sheet Composition of Palygorskite

2007 ◽  
Vol 55 (6) ◽  
pp. 543-553 ◽  
Author(s):  
Vassilis Gionis ◽  
George H. Kacandes ◽  
Ioannis D Kastritis ◽  
Georgios D. Chryssikos
Keyword(s):  
Near Infrared ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
X Ray

Changes in kaolinite, vermiculite, and smectite clays after adsorption by hydroxy-chromium species

Soil Research ◽  
1998 ◽  
Vol 36 (3) ◽  
pp. 423 ◽  
Author(s):  
Cristina Volzone
Keyword(s):  
Surface Area ◽  
Nitrate Solution ◽  
Basal Spacing ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
Chromium Species ◽  
X Ray ◽  
Micropore Surface Area ◽  
Smectite Clays ◽  
Adsorption Desorption

Kaolinite, vermiculite, and montmorillonites were treated with solutions containing hydroxy-chromium (OH-Cr) species. The OH-Cr solution was prepared by adding 0·2 М NaOH to 0·1 М chromium nitrate solution and allowing the solution to stand at 60°C for 1 day. The samples were characterised by chemical analyses, N2 adsorption-desorption isotherms, and X-ray diffraction. The textural and structural behaviours of kaolinite, vermiculite, and the montmorillonites were analysed in the original samples and after treatment with the polymeric OH-Cr species. The montmorillonites showed higher retention of chromium (19·20%), higher basal spacing (2·06 nm), and higher micropore surface area (276 m2/g) than the vermiculite (3·70%, 1·49 nm, 13 m2/g) and kaolinite (1·15%, 0·73 nm, ~1 m2/g) clays after treatment with the OH-Cr species. In contrast, the external surface area increased from 6 to 9 m2/g for kaolinite and from 18 to 24 m2/g for vermiculite, and decreased from 7 to 4 m2/g for montmorillonite after treatment with the OH-Cr solution. The residual chromium, basal spacing, and texture of the clays after treatment with the OH-Cr species were primarily related to the magnitude of the negative charge originating from the octahedral sheet.

Preparation of Heterojunction Semiconductor SnS2/SnO2 with Enhanced Photocatalytic Properties

2013 ◽  
Vol 316-317 ◽  
pp. 1059-1062 ◽  
Author(s):  
Ping Chen ◽  
Ming Sheng Qin ◽  
Fu Qiang Huang
Keyword(s):  
Photocatalytic Activity ◽  
Single Phase ◽  
Near Infrared ◽  
Photocatalytic Performance ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Simple Method ◽  
X Ray ◽  
Structure Morphology ◽  
Nir Absorption

The Formation of Heterojunction Structure between Two Semiconductors Was Considered as an Effective Method to Enhance the Photocatalytic Activity. here, we Reported a Simple Method to Prepare SnS2/SnO2Heterojunction Photocatalysts by Annealing SnS2in Air. the Structure, Morphology, Chemical Compositions and Optical Properties of the Obtained Materials Were Characterized by the X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDX) and Ultraviolet-visible-near Infrared (UV-Vis-NIR) Absorption Spectra. the Photocatalytic Investigations Showed the Composites Have Higher Photocatalytic Activity than the Single-phase SnS2. the SnS2Powder which Annealed at 400 °C for 60 Min Showed the Highest Photocatalytic Performance.

Influence of Sputtering Power on the Structure, Optical and Electric Properties of Cu3N Films

2015 ◽  
Vol 814 ◽  
pp. 596-600 ◽  
Author(s):  
Li Na Chen ◽  
Jin Feng Leng ◽  
Zhong Xi Yang ◽  
Zhi Chao Meng ◽  
Bin Sun
Keyword(s):  
Near Infrared ◽  
Optical Band Gap ◽  
Infrared Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputtering Power ◽  
Deposition Power ◽  
Higher Power ◽  
Uv Visible ◽  
Peak Value

The Cu3N films were deposited successfully by reactive direct current magnetron sputtering, the films were comprehensively and systematically characterized by X-ray diffraction analyzer (XRD), UV-Visible spectrophotometer, four-probe resistance tester and other instruments. Results showed that under low deposition power (80W~100W), crystal orientation increased, which is attributed to higher energy under higher power. When sputtering power exceeded the value, excessive energy led to anti-sputtering hindering the process of further nucleation and growth of films. The transmittance of the films deposited under 100W reached the peak value of 78% on the scope of near-infrared light, and optical band gap (Eg) of 1.35ev. The resistivity of Cu3N films increased from 9.68×102Ω.cm to 2.12×103Ω.cm with increasing in sputtering power up to 100W.

Synthesis, Characterization and Optical Properties of Y6-xSmxMoO12+σ Composite/Compounds Pigments with High Near-Infrared Reflectance

2012 ◽  
Vol 602-604 ◽  
pp. 102-106 ◽  
Author(s):  
Xiao Yu Zhang ◽  
Yu Jun Zhang ◽  
Hong Yu Gong ◽  
Xin Qiao Zhao ◽  
Cui Ling Wang ◽  
...  
Keyword(s):  
Near Infrared ◽  
Solid State Reaction Method ◽  
Inorganic Pigments ◽  
Infrared Reflectance ◽  
X Ray Diffraction ◽  
Near Infrared Reflectance ◽  
X Ray ◽  
Bright Yellow ◽  
Simple Solid State Reaction ◽  
Color Scales

Novel high near-infrared reflecting inorganic pigments Y6-xSmxMoO12+σ (03+ in yttrium molybdate through a simple solid-state reaction method. The composites were characterized using scanning electron microscope, X-ray diffraction, UV-vis-NIR spectrophotometer and CIE 1976 L*a*b* color scales. The substitution of Sm3+ for Y3+ in Y6MoO12 changed the color from bright yellow to dark yellow and most importantly increased near-infrared reflectance in the wavelength range of 700-2500 nm. The chemical stability of the pigments was also evaluated.

scholarly journals Unique but diverse: some observations on the formation, structure and morphology of halloysite

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 395-416 ◽  
Author(s):  
G. Jock Churchman ◽  
P. Pasbakhsh ◽  
D.J. Lowe ◽  
B.K.G. Theng
Keyword(s):  
Organic Molecules ◽  
Recent Literature ◽  
Low Ph ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
X Ray ◽  
Structure And Morphology ◽  
Fe Content ◽  
Sheet Charge ◽  
Positively Charged

AbstractNew insights from the recent literature are summarized and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is positively charged at pH < ∼8, whereas the tetrahedral sheet is negatively charged at pH > ∼2. The opposing sheet charge would facilitate interlayer uptake of H2O molecules. When halloysite intercalates certain polar organic molecules, additional (hkl) reflections appear in the X-ray diffraction pattern, suggesting layer re-arrangement which, however, is dissimilar to that in kaolinite. Associated oxides and oxyhydroxides of Fe and Mn may limit the growth of halloysite particles as does incorporation of Fe into the structure. Particles of different shape and Fe content may occur within a given sample of halloysite.

Growth and Magneto-Optical Properties of CaTbAlO4 Crystal

2011 ◽  
Vol 306-307 ◽  
pp. 1722-1727 ◽  
Author(s):  
Man Mei ◽  
Li Li Cao ◽  
Yan He ◽  
Ru Ru Zhang ◽  
Fei Yun Guo ◽  
...  
Keyword(s):  
Optical Properties ◽  
Single Crystal ◽  
Room Temperature ◽  
Near Infrared ◽  
Visible Region ◽  
Czochralski Method ◽  
Optical Devices ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Spectral

The calcium terbium aluminate (CaTbAlO4) single crystal was grown by Czochralski method successfully for the first time.The structure of the crystal was determined by X-ray diffraction analysis.The transmission spectrum of the crystal was measured at room temperature at the wavelength of 400-1500nm.The specific Faraday rotation of the single crystal was surveyed at room temperature at the wavelength 532nm, 633nm, and 1064nm respectively.The Verdet constants of the CaTbAlO4 crystal are calculated and the results show that the Verdet constants of CaTbAlO4 are around 110% higher than that of TGG in the visible and near-infrared spectral region.Therefore,crystal CaTbAlO4 can be promising material for the fabrication of magneto-optical devices in the visible region.

scholarly journals The effect of the octahedral cations on the dimensions of the palygorskite cell

Clay Minerals ◽  
2007 ◽  
Vol 42 (3) ◽  
pp. 287-297 ◽  
Author(s):  
M. Suárez ◽  
E. García-Romero ◽  
M. Sánchez Del Río ◽  
P. Martinetto ◽  
E. Dooryhée
Keyword(s):  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Ionic Radii ◽  
Octahedral Sheet ◽  
X Ray ◽  
Linear Dependency ◽  
Octahedral Cation ◽  
Analytical Electron ◽  
Octahedral Cations

AbstractHigh-resolution synchrotron X-ray diffraction recorded on a collection of palygorskites with different chemical compositions (obtained by analytical electron microscopy) permits unambiguous correlation of the crystallographic parameters a (or a sin β if a monoclinic phase is considered) with the nature of the octahedral sheet, i.e. with both the number of octahedral positions that are occupied and the type of octahedral cation. No significant changes in the lattice parameters b and c are observed. The unit cell modification consists essentially of an expansion in a as the number of cations with larger ionic radii (Mg2+ and Fe3+) predominates over smaller cations (Al3+). A linear dependency of a (or a sin β) on the chemical composition of the octahedral sheet was obtained that can be used for classifying palygorskite into compositional groups, using only conventional diffraction data, without the need for chemical analyses.

scholarly journals Thermal behaviour of stevensite at temperatures up to 800°C.

2016 ◽  
Vol 47 (1) ◽  
pp. 366
Author(s):  
G. E. Christidis ◽  
E. Koutsopoulou
Keyword(s):  
Clay Fraction ◽  
Experimental Setup ◽  
Layer Silicate ◽  
X Ray Diffraction ◽  
Octahedral Sheet ◽  
X Ray ◽  
End Products ◽  
Trioctahedral Smectite ◽  
Current Experimental Setup ◽  
Transformation Pattern

Stevensite is a Mg-trioctahedral smectite with layer charge stemming from vacancies in the octahedral sheet. In the present work we studied the thermal behavior of Jbel Ghassoul stevensite from Morocco, known as Ghassoulite or Rhassoulite, free of talc layers. The clay fraction of the material was separated by sedimentation, it was subsequently heated from 250° to 800° C and the end products were examined with X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The influence of heating on the stevensite structure begins at 400°C and is completed at 500°C. It involves irreversible collapse of the layers at ~10Å, which do not re-expand in ethylene glycol (EG) vapors. In contrast, heating at lower temperatures does not affect the stevensite layers, which expand completely in EG. The FTIR spectra indicate the formation of talc-like (kerolite) layers after heating at temperatures exceeding 400°C. Within the current experimental setup, the transition to kerolite layers takes place without the formation of an intermediate mixed-layer stevensite/talc phase. Heating at higher temperatures does not change the transformation pattern, until 800°C where complete dehydroxylation of the 2:1 layer takes place, which is associated with the formation of enstatite. The results of this study clearly demonstrate that opposite to common trioctahedral and dioctahedral smectites, stevensite converts to another layer silicate prior to dehydroxylation.

Synthesis and photoelectric properties of SnSe films through selenization of evaporated Sn-metal films

2021 ◽  
pp. 2150382
Author(s):  
Shun Wang ◽  
Honglie Shen ◽  
Shusong Cui ◽  
Yufang Li
Keyword(s):  
Near Infrared ◽  
Metal Films ◽  
Electron Beam Evaporation ◽  
Infrared Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Response Characteristics ◽  
Photoelectric Properties ◽  
Pure Phase ◽  
Large Application

Sn precursor layer was evaporated on a glass substrate by an electron-beam evaporation method and followed by selenization using Se powder. SnSe film was successfully prepared by adjusting the selenization temperature and selenization time. The phase, microstructure and optical properties of the SnSe films were studied by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, and UV-Vis-NIR spectrophotometer. The results demonstrated that the pure phase polycrystalline SnSe films with a band gap of 0.93 eV could be prepared by selenizing at 450[Formula: see text]C for 60 min. Under the irradiation of a 980 nm laser with a power of 2 mW/cm2, photoelectric response characteristics of the SnSe films were tested, and the response time and recovery time of the prepared film were 62 ms and 80 ms, respectively, indicating that the SnSe film had a large application prospect in near-infrared light detection.

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