搜索结果: 1-15 共查到“理学 Ferrihydrite”相关记录25条 . 查询时间(0.221 秒)
Enrichment of Phosphate on Ferrous Iron Phases during Bio-Reduction of Ferrihydrite
Phosphate Iron Reduction Ferrihydrite Ferrous Iron Vivianite
2013/3/7
The reduction of less stable ferric hydroxides and formation of ferrous phases is critical for the fate of phosphorus in anaerobic soils and sediments. The interaction between ferrous iron and phospha...
Shifted loops and coercivity from field imprinted high energy barriers in ferritin and ferrihydrite nanoparticles
Shifted loops coercivity from field ferrihydrite nanoparticles
2010/11/25
We show that the coercive field in ferritin depends on the maximum magnetic field in a ysteresis loop and that coercivity and loop shifts depend both on the maximum and cooling fields. The time depend...
Ferrihydrite的亚微观结构对反应活性的影响
Ferrihydrite 亚微观结构 α-Fe2O3 反应活性
2010/1/14
以Fe(III)盐为原料、NaOH为沉淀剂、采用三种方法调控制备了ferrihydrite, 借助X射线衍射(XRD)、红外光谱(IR)、差热分析(DTA)及其在稀盐酸中的溶解速率等手段对其结构进行了表征, 探讨了ferrihydrite的形成环境对其亚微观结构及其反应活性的影响. 结果表明, 不同方法制备的ferrihydrite的亚微观结构不同, 恒pH条件下制备的ferrihydrite结构...
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...