Laser Vaporization of Magnetic FexOy and FexOy-SiO2 Nanoparticles for Biomedical Applications

2012 ◽  
Vol 529-530 ◽  
pp. 605-608
Author(s):  
Christian Stötzel ◽  
Heinz Dieter Kurland ◽  
Janet Grabow ◽  
Frank A. Müller
Keyword(s):  
Iron Oxide ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Biomedical Applications ◽  
Particle Morphology ◽  
Oxide Phase ◽  
Composite Nanoparticles ◽  
Laser Vaporization ◽  
Process Gas ◽  
Iron Oxide Phase

Magnetic iron oxide (FexOy) and iron oxide/silica (FexOy/SiO2) composite nanoparticles were synthesized by CO2 laser vaporization (LAVA) of an α-Fe2O3 raw powder and α-Fe2O3/quartz sand mixtures, respectively. Particle morphology, composition and iron oxide phase formation were investigated by transmission electron microscopy and X-ray diffraction. The resulting nanopowders mainly consisted of magnetite (Fe3O4) and maghemite (γ-Fe2O3). Increasing the oxygen partial pressure in the LAVA process gas an additional iron oxide phase, ε-Fe2O3, occurred. The saturation magnetization of the iron oxide nanoparticles was determined with vibrating sample magnetometry and was found to decrease with increasing oxygen partial pressure in the process gas. FexOy/SiO2 composite nanoparticles are of particular interest for biomedical applications because their silica surface can be functionalized very easily.

scholarly journals Implications of the iron oxide phase transition on the interiors of rocky exoplanets

2021 ◽  
Author(s):  
F. Coppari ◽  
R. F. Smith ◽  
J. Wang ◽  
M. Millot ◽  
D. Kim ◽  
...  
Keyword(s):  
Phase Transition ◽  
Iron Oxide ◽  
Oxide Phase ◽  
Iron Oxide Phase

Synthesis and crystallogenesis at low temperature of Fe(III)-smectites by evolution of coprecipitated gels: experiments in partially reducing conditions

Clay Minerals ◽  
1986 ◽  
Vol 21 (5) ◽  
pp. 861-877 ◽  
Author(s):  
A. Decarreau ◽  
D. Bonnin
Keyword(s):  
Crystal Growth ◽  
Iron Oxide ◽  
Low Temperature ◽  
Oxide Phase ◽  
Octahedral Sheet ◽  
Reducing Conditions ◽  
Iron Oxide Phase

AbstractSyntheses of ferric smectites were performed at low temperature (75° C by aging coprecipitated gels of silica and Fe2+-sulphate under initially reducing then oxidizing conditions. Under strictly reducing conditions only nuclei of a trioctahedral ferrous stevensite were observed and crystal growth did not take place. When a spontaneous oxidization, in contact with air, was effected, the ferrous smectite nuclei transformed rapidly into a ferric, nontronite-like, smectite. Crystallogenesis of the ferric smectite was studied by XRD, IR, DTA, Mössbauer and EPR spectroscopies. The end-synthesis smectite contained only Fe3+ions, all located in the octahedral sheet. This clay was mixed with a cryptocrystalline iron oxide phase containing one-third of the iron atoms and undetectable by XRD.

Functionalisation of Glass with Iron Oxide Nanoparticles Produced by Laser Pyrolysis

2008 ◽  
Vol 8 (5) ◽  
pp. 2458-2462
Author(s):  
V. de Castro ◽  
G. Benito ◽  
S. Hurst ◽  
F. Cebollada ◽  
C. J. Serna ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Glass Production ◽  
Oxide Phase ◽  
Experimental Conditions ◽  
Silica Substrate ◽  
New Process ◽  
Iron Phase ◽  
Production Technologies ◽  
The Moment ◽  
Iron Oxide Phase

In the present work, a new process for depositing nanoparticle layers onto glass has been developed by using one of the most interesting nanoparticle generation technologies at the moment, which is based on the pyrolysis induced by laser of vapours combined with CVD of the particles onto glass. Nanoparticles prepared by this method were deposited into a hot silica substrate obtaining new nanocomposites with unique properties. The coated glasses present new specific functionalities such as colour, and interesting magnetic and optical properties. Control of the thickness and the iron oxide phase, either magnetic or not, has been achieved by adjusting the experimental conditions. Thus, thickness is controlled by the glass and the precursor temperature, while the iron phase is controlled by the precursor temperature and the nature and the flow of the carrier gas. This process is inexpensive, adaptable to current glass production technologies and takes place at atmospheric pressure.

Thermochemical Comparison of the Systems Re-O and Tc-O

1988 ◽  
Vol 127 ◽  
Author(s):  
H. Migge
Keyword(s):  
Fission Product ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Nuclear Waste ◽  
Half Life ◽  
Thermodynamic Data ◽  
Thermochemical Treatment ◽  
Oxide Phase

Technetium is a hazardous fission product with a long half-life. In vitrification of nuclear waste, technetium tends to be lost substantially by evaporation [1], and the formation of gaseous Tc oxides is assumed to be the reason. Reliable thermochemical treatment of the problem is difficult, since data on the Tc-O system are surprisingly scarce [2]. Therefore, the system Re-O is treated for comparison. Key thermodynamic data for the condensed rhenium oxides exist [3,4,5] as well as measurements on the sublimation and the evaporation of the oxides [6–11]. Consistency of the different data is investigated by assessing the sublimation data of solid Re2O7, using them to calculate other sublimation equilibria and to compare the results with published measurements. Then a predominance area diagram is constructed and discussed with respect to the pressures of the gaseous oxides and their dependence on the temperature, oxygen partial pressure, and condensed oxide phase present. Predominance area diagrams of the Tc-O system are calculated and critically discussed. Owing to the small amout of available data, the possible existence of solid TcO3 is discussed. Comparison with the system Re-O is used to clarify, where further investigations need to be done.

scholarly journals Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor

Nanoscale ◽  
2021 ◽  
Author(s):  
Maximilian O. Besenhard ◽  
Luca Panariello ◽  
Céline Kiefer ◽  
Alec P. LaGrow ◽  
Liudmyla Storozhuk ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Flow Reactor ◽  
Oxide Phase ◽  
Particle Growth ◽  
Oxide Nanoparticles ◽  
T1 Contrast Agent ◽  
T1 Contrast ◽  
Co Precipitation ◽  
Iron Oxide Phase

Small iron oxide nanoparticles (IONPs) were synthesised in water via co-precipitation by quenching particle growth after the magnetic iron oxide phase formed.

Evidence for the multiphase nature of bentonites from Mössbauer and EPR spectroscopy

Clay Minerals ◽  
1988 ◽  
Vol 23 (2) ◽  
pp. 147-159 ◽  
Author(s):  
B. A. Goodman ◽  
P. H. Nadeau ◽  
J. Chadwick
Keyword(s):  
Iron Oxide ◽  
Ambient Temperature ◽  
Epr Spectroscopy ◽  
Magnetic Ordering ◽  
Oxide Phase ◽  
Additional Component ◽  
Rich Phase ◽  
Fe Content ◽  
Structural Environment ◽  
Iron Oxide Phase

AbstractMössbauer spectra of several smectites demonstrate the existence of at least three phases with distinct Fe populations: (i) a component with very low Fe content (< 1%), which shows slowly-relaxing paramagnetic hyperfine structure at both 4·2 K and 77 K; (ii) a component with intermediate Fe content (∼ 1–10%) which is seen as doublets in the spectra at 4·2 K, 77 K and ambient temperature; (iii) an Fe-rich phase (> 30% Fe), which shows magnetic ordering at 4·2 K and 77 K. These data are consistent with components (i) and (ii) corresponding to Fe incorporated in aluminosilicate structures from distinct phases, whereas (iii) is characteristic of an iron oxide phase, probably goethite in most cases. These conclusions are supported by EPR measurements which show magnetically-dilute Fe in more than one type of structural environment plus an additional component with magnetically-interacting ions.

scholarly journals A new hydrous iron oxide phase stable at mid-mantle pressures

2020 ◽  
Vol 550 ◽  
pp. 116551
Author(s):  
Huawei Chen ◽  
Sheng-Yi Xie ◽  
Byeongkwan Ko ◽  
Taehyun Kim ◽  
Carole Nisr ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Oxide Phase ◽  
Hydrous Iron Oxide ◽  
Iron Oxide Phase
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