X-ray spectromicroscopy of nanoparticulate iron oxide phases

2016 ◽  
Vol 11 (4) ◽  
pp. 04B402 ◽  
Author(s):  
Paul M. Dietrich ◽  
Wolfgang E. S. Unger ◽  
Sufal Swaraj
Keyword(s):  
Iron Oxide ◽  
X Ray ◽  
Oxide Phases

Selective Depositions of Fe-Containing Oxide Films on Mixed Selfassembled Organic Monolayers using Microcontact Printing

1999 ◽  
Vol 576 ◽  
Author(s):  
Hyunjung Shin ◽  
Hyejin Im ◽  
Seungbum Hong ◽  
Kyongmi Lee ◽  
Geunbae Lim ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Aqueous Solutions ◽  
Microcontact Printing ◽  
Thin Layers ◽  
Organic Monolayers ◽  
Selective Deposition ◽  
X Ray ◽  
Si Substrates ◽  
Relief Structure ◽  
Oxide Phases

ABSTRACTIn situ patterning of crystalline iron oxide thin layers has been achieved via microcontact printing (μCP) and selective deposition. μCP was used to pattern two different surface moieties of selfassembled organic monolayers (SAMs) on Au/Cr/Si substrates. An elastomeric stamp (poly(dimethylsiloxane); PDMS) having a submicron-size patterned relief structure was used to transfer either hexadecanethiol (HDT) SAMs, which are to sustain deposition of iron oxide precipitates, or hydrophilic SAMs (e.g. dithiothreitol (DTT)). Selective deposition is realized through precipitation of iron oxide phases from aqueous solutions at ambient temperature (<100°C). Aqueous solutions of 0.05 M of iron nitrate (Fe(NO3)2•9H20) containing urea under nitric acid (pH < 2) were prepared for selective depositions. X-ray photoelectron spectroscopic (XPS) results showed that iron oxide precipitates were deposited onto hydrophilic SAMs, but not onto HDT surfaces. As-deposited films onto DTT-SAM surfaces at 80°C were crystalline α-Fe2O3 (hematite). Fe3O4 and γ-Fe2O3 films were synthesized via annealing of as-deposited α-Fe2O3. Scanning electron microscopy, x-ray diffractometry, vibrating sample magnetometry, and optical microscopy were used to characterize the films' microstructures and properties.

Identification of iron oxide phases in thin films grown on Al2O3(0001) by Raman spectroscopy and X-ray diffraction

2010 ◽  
Vol 604 (7-8) ◽  
pp. 679-685 ◽  
Author(s):  
Maike Lübbe ◽  
Alexander M. Gigler ◽  
Robert W. Stark ◽  
Wolfgang Moritz
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Iron Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Phases

The thermal disintegration of crocidolite in air and in vacuum

1965 ◽  
Vol 35 (269) ◽  
pp. 31-37 ◽  
Author(s):  
J. H. Patterson
Keyword(s):  
Iron Oxide ◽  
Structural Models ◽  
Fibre Axis ◽  
Orientation Relationships ◽  
Incongruent Melting ◽  
Fibre Bundles ◽  
X Ray ◽  
Oxide Phases ◽  
Original Fibre

SummaryThe thermal disintegration of crocidolite has been investigated with X-ray powder and rotation photographs. Initial disintegration products include monoclinic pyroxene, iron oxide phases, and eristobalite as a pseudomorph of the original fibre bundles but at about 1000° C fusion occurs due to incongruent melting of the pyroxene. The products are strongly oriented along the fibre axis and full orientation relationships have been deduced with the aid of structural models. From these relationships it is suggested that regions of the amphibole structure on (100) are retained in the product phases without change in orientation.

Reaction Pathways at the Iron–microspherical Silica Interface: Mechanistic Aspects of the Formation of Target Iron Oxide Phases

2000 ◽  
Vol 15 (4) ◽  
pp. 944-950 ◽  
Author(s):  
Sivarajan Ramesh ◽  
Israel Felner ◽  
Yuri Koltypin ◽  
Aharon Gedanken
Keyword(s):  
Iron Oxide ◽  
Iron Nanoparticles ◽  
Silica Surface ◽  
Adsorbed Water ◽  
Reaction Pathways ◽  
X Ray ◽  
Degree Of Hydration ◽  
Oxide Phases ◽  
And Control ◽  
Hydrolysis Of

Oxidative hydrolysis of elemental iron nanoclusters on hydroxylated surfaces such as silica or alumina is known to be influenced by the degree of hydration of the surface. The understanding and control of this process is crucial in the synthesis of iron oxide coated silica microspheres with a desired magnetic property. The hydrolysis of iron nanoparticles followed by heat treatment in the case of a hydrated microspherical silica surface results in the formation of maghemite (γ–Fe2O3), whereas a dehydrated surface yielded hematite (α–Fe2O3) nanoparticles. The influence of adsorbed water on the formation of intermediate iron oxides/oxidehydroxides and the mechanistic aspects of their subsequent thermal dehydration iron oxide phases were investigated by thermogravimetric analysis, Fourier transform infrared, and Mössbauer spectroscopies. The reactions on both the hydrated and the dehydrated surfaces were found to proceed through the formation of an x-ray amorphous lepidocrocite [γ–FeO(OH)] intermediate and its subsequent dehydration to maghemite (γ–Fe2O3). Maghemite to hematite transformation was readily facilitated only on a dry silica surface. The retardation of the lepidocrocite →maghemite →hematite transformation in the case of a hydrated silica surface is suggested to arise from strong hydrogen-bonded interactions between the substrate silica and the adsorbed nanoparticles.

scholarly journals Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

2021 ◽  
Author(s):  
Stephan Müssig ◽  
Björn Kuttich ◽  
Florian Fidler ◽  
Daniel Haddad ◽  
Susanne Wintzheimer ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Light Scattering ◽  
Superparamagnetic Iron Oxide ◽  
Iron Oxide Nanoparticle ◽  
Oxide Nanoparticles ◽  
X Ray ◽  
X Ray Scattering ◽  
Nanoparticle Dispersions ◽  
Oxide Nanoparticle

The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide...

scholarly journals Direct Production of a Novel Iron-Based Nanocomposite from the Laser Pyrolysis ofFe(CO)5/MMAMixtures: Structural and Sensing Properties

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
R. Alexandrescu ◽  
I. Morjan ◽  
A. Tomescu ◽  
C. E. Simion ◽  
M. Scarisoreanu ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Gas Sensors ◽  
High Sensitivity ◽  
X Ray Diffraction ◽  
Direct Production ◽  
X Ray ◽  
Metallic Particles ◽  
Ir Laser ◽  
Iron Iron ◽  
Optimum Working

Iron/iron oxide-based nanocomposites were prepared by IR laser sensitized pyrolysis ofFe(CO)5and methyl methacrylate (MMA) mixtures. The morphology of nanopowder analyzed by TEM indicated that mainly core-shell structures were obtained. X-ray diffraction techniques evidence the cores as formed mainly by iron/iron oxide crystalline phases. A partially degraded (carbonized) polymeric matrix is suggested for the coverage of the metallic particles. The nanocomposite structure at the variation of the laser density and of the MMA flow was studied. The new materials prepared as thick films were tested for their potential for acting as gas sensors. The temporal variation of the electrical resistance in presence ofNO2, CO, andCO2, in dry and humid air was recorded. Preliminary results show that the samples obtained at higher laser power density exhibit rather high sensitivity towardsNO2detection andNO2selectivity relatively to CO andCO2. An optimum working temperature of200°Cwas found.

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Monoclinic FeO at high pressures

2008 ◽  
Vol 223 (7/2008) ◽  
Author(s):  
Innokenty Kantor ◽  
Alexander Kurnosov ◽  
Catherine McCammon ◽  
Leonid Dubrovinsky
Keyword(s):  
High Pressure ◽  
Iron Oxide ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray

AbstractA high-pressure quasi-single crystal X-ray diffraction study of a synthetic iron oxide Fe

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