搜索结果: 1-15 共查到“地质学 Ferrihydrite”相关记录22条 . 查询时间(0.046 秒)
Transmission Electron Microscopy of Synthetic 2- and 6-Line Ferrihydrite
Ferrihydrite High-Resolution Transmission Electron Microscopy (HRTEM) Nanodiffraction Selected-Area Electron Diffraction (SAED)
2011/12/2
Abstract: High-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), annular dark-field scanning transmission electron microscope (STEM) images, and electron ...
Inhibition of Sintering by Si During the Conversion of Si-Rich Ferrihydrite to Hematite
BET Ferrihydrite Si Sintering XPS
2011/12/2
Abstract: The distribution and chemical state of Si in a synthetic 2-line ferrihydrite with a Si/(Si + Fe) molar ratio of 0.11 was studied. Heat treatment under oxidizing conditions shows that Si-rich...
The Effect of Al on Fe Oxides. XIX. Formation of Al-Substituted Hematite from Ferrihydrite at 25C and pH 4 To 7
Al-Substituted Hematite Formation of Fe Oxide Hyperfine Fields Structural OH Synthesis of Fe Oxides Unit-Cell Size
2011/12/5
Abstract: Iron oxides in surface environments generally form at temperatures of 25 ?10癈, but synthesis experiments are usually done at higher temperatures to increase the rate of crystallization. To m...
Formation of Goethite and Hematite from Neodymium-Containing Ferrihydrite Suspensions
Ferrihydrite Goethite Hematite Neodymium Powder X-ray Diffractometry Rietveld Refinement Transmission Electron Microscopy
2011/12/8
Abstract: The effects of neodymium (Nd) on the transformation of ferrihydrite to iron oxides was studied. The possible isomorphous substitution of Nd3+ for Fe3+ in iron oxides was examined also. Nd wa...
Effect of Phosphate on the Crystallization of Hematite, Goethite, and Lepidocrocite from Ferrihydrite
Crystallization Ferrihydrite Goethite Hematite Lepidocrocite Phosphate
2011/12/7
Abstract: We investigated the crystallization of ferrihydrite prepared by hydrolysis of Fe(NO3)3 solutions containing phosphate. Crystallization was studied at different pH (3–9), temperatures (298, 3...
Stirring Effects on Properties of Al Goethite Formed from Ferrihydrite
Al Goethite Crystallinity Hematite Stirring Unit Cell Parameters
2011/12/8
Abstract: Minerals in surface environments form in both turbulent and non-turbulent systems. This study compares the properties of Al goethite formed from ferrihydrite at 60 °C in 0.3 M KOH with and w...
Surface Structural Model for Ferrihydrite
EXAFS Ferrihydrite Hydrous Ferric Oxide XANES X-ray Absorption Spectroscopy
2011/12/22
Abstract: A structural model for the geometry of Fe(III) octahedra near the surface of finely divided ferrihydrite was elaborated based on the bond梫alence theory and by considering the interaction of ...
Ferrihydrite: Surface Structure and its Effects on Phase Transformation
Ferrihydrite Mossbauer spectroscopy Phase transformation Surface structure X-ray absorption fine structure (XAFS)
2011/12/29
X-ray absorption fine structure (XAFS) spectra were collected on a series of ferrihydrite samples prepared over a range of precipitation and drying conditions. Analysis of the XAFS pre-edge structures...
Studies of the Reactivity of the Ferrihydrite Surface by Iron Isotopic Exchange and Mossbauer Spectroscopy
Adsorption Arsenate Dissolution kinetics Ferrihydrite Iron octahedra Mossbauer spectroscopy Reactive sites Solubility Surface chemistry
2011/12/1
Abstract: Two-line ferrihydrite is an important adsorbent of many toxics in natural and anthropogenic systems; however, the specific structural sites responsible for the high adsorption capacity are n...
A Structural Model for Natural Siliceous Ferrihydrite
Domain size Ferrihydrite Low-angle X-ray diffraction (LAXRD) Particle size Silicate Structure X-ray diffraction (XRD)
2011/12/31
X-ray diffraction of four natural samples of ferrihydrite indicates the presence of crystalline domains within the primary particles. The average diameter of the primary particles (determined from low...
Color Variations Associated with Rapid Formation of Goethite from Proto-Ferrihydrite at pH 13 and 40°C
Crystallization Colorimetry Goethite Infrared spectroscopy L*a*b* color space UV-VIS-NIR spectroscopy X-ray diffractometry
2011/12/31
Color variations from brown to yellow of synthesized goethite have been studied colorimetrically and spectroscopically. Goethite with various colors was synthesized at pH 13 and 40°C by varying the in...
Structural and Magnetic Properties of Ferrihydrite
Ferrihydrite Ferrimagnetism Antiferromagnetism
2011/12/30
57Fe M鰏sbauer spectra of two synthetic samples of ferrihydrite, recorded at 4.2 K in applied fields of up to 9 T, have been analysed by a mean-field model. The samples exhibit two and six X-ray diffra...
Infrared Vibrations of Hematite Formed From Aqueous- and Dry-Thermal Incubation of Si-Containing Ferrihydrite
Ferrihydrite Hematite Infrared spectroscopy Morphology Silicon Thermal treatment
2012/1/4
Ferrihydrite samples having Si/Fe molar ratios ranging from 0 to 1 were synthesized by the reaction of Fe2(SO4)3 and Na2SiO3 with NaOH to an equilibrium pH of 8.2. Hematite formed by incubating the fe...
Effect of Cobalt on the Formation of Crystalline Iron Oxides from Ferrihydrite in Alkaline Media
Cobalt Crystal growth Ferrihydrite Goethite Spinel Transmission electron microscopy
2011/11/30
Abstract: At pH 12 Co-ferrihydrite transformed to either Co-goethite or Co-magnetite, the latter compound appearing at Co additions of > 18 mole %. Although Co was readily taken up by the magnetite st...
Influence of Structural and Adsorbed Si on the Transformation of Synthetic Ferrihydrite
Adsorption Crystal structure Ferrihydrite Infrared spectroscopy Silicon Synthesis X-ray powder diffraction
2012/1/5
The transformation of ferrihydrite to goethite and/or hematite, as influenced by the presence of co-precipitated Si, was investigated by infrared spectroscopy (IR), X-ray powder diffraction (XRD), and...
