نتایج جستجو برای: Spinel structure

تعداد نتایج: 1570753  

Journal: :international journal of nano dimension 0
m. k. shobana center for advanced material technology, kookmin university, 861-1 jeongneung-dong, seongbuk-gu, seoul 136-702, republic of korea.

the mössbauer spectra of nanoferrite materials such as ni0.25mn0.75fe2o4, co0.5mn0.5fe2o4 and ni0.4co0.6fe2o4 have been reported and the above materials were prepared by sol-gel combustion method using metal nitrates as source material and polyvinyl alcohol(pva) as agglomeration reducing agent. as the structural, thermal and magnetic properties (vsm) of the above ferrites have been published al...

2016
Nik Reeves-McLaren Joanne Sharp Héctor Beltrán-Mir W. Mark Rainforth Anthony R. West

The transformation on heating LiCoMnO4, with a spinel structure, to LiCoMnO3, with a cation-disordered rock salt structure, accompanied by loss of 25% of the oxygen, has been followed using a combination of diffraction, microscopy and spectroscopy techniques. The transformation does not proceed by a topotactic mechanism, even though the spinel and rock salt phases have a similar, cubic close-pa...

2013
J. M. PAQUE S. R. SUTTON S. B. SIMON J. R. BECKETT D. S. BURNETT L. GROSSMAN H. YURIMOTO S. ITOH CONNOLLY

Ti valence measurements in MgAl2O4 spinel from calcium-aluminum-rich inclusions (CAIs) by X-ray absorption near-edge structure (XANES) spectroscopy show that many spinels have predominantly tetravalent Ti, regardless of host phases. The average spinel in Allende type B1 inclusion TS34 has 87% Ti. Most spinels in fluffy type A (FTA) inclusions also have high Ti valence. In contrast, the rims of ...

2014
Anitha Rani

Ferrites with spinel structure are the most widespread materials in radio engineering, electronics and communication industry, microwave devices and computer facilities. The change of synthesis temperature of ferrites results in cation redistribution of iron, which updates crystal properties, as macroscopic magnetic properties of ferrites. Among this extensive class of compounds nickel and copp...

2017
Ilona Jastrzębska Wiktor Bodnar Kerstin Witte Eberhard Burkel Paweł Stoch Jacek Szczerba

Spinels are compounds that have the general formula AB2O4 where A and B are metallic cations. The formal charges of A and B are strictly specifi ed and they are a criterion of the spinel type. There are three types of spinel compounds, the so-called 2-3, 4-2 and 6-1 spinels, where the numbers indicate the formal charges of the cations. The fi rst cation of each pair occupies a tetrahedral site ...

Journal: :iranian journal of earth science 0
jamal tarrah islamic azad university, bandar abbas branch, geology department, bandar abbas, iran zahra abedpour islamic azad university, bandar abbas branch, geology department, bandar abbas, iran karl strauss institute of mineralogy-geochemistry and salt deposits, university of clausthal, germany thomas schirmer institute of mineralogy-geochemistry and salt deposits, university of clausthal, germany kurt mengel institute of mineralogy-geochemistry and salt deposits, university of clausthal, germany

ten chromite ores from ophiolite complexes in se iran were analyzed mineralogically by xrd, chemically by xrf, and mineral chemistry by epma. the identified paragenesis of silicate minerals of chromite ores with the x-ray diffraction is pronounced differently. it consists of secondary phases formed as serpentine, cr-containing chlorite (kaemmererite), chromic garnet (uarovite) with preserved pa...

2008
Carlos Bárcena Amandeep K. Sra Girija S. Chaubey Chalermchai Khemtong J. Ping Liu Jinming Gao

Magnetic resonance imaging (MRI) is a powerful clinical imaging technique for the non-invasive diagnosis and posttherapy assessment of a variety of diseases. MRI contrast can be enhanced by the use of positive or negative contrast agents resulting in brighter (T1-weighted) or darker (T2-weighted) images, respectively. Superparamagnetic iron oxide (SPIO) nanoparticles are T2 contrast agents that...

2013

Magnetic oxides are naturally occurring minerals. In order to understand their unique properties and their utilization in technological applications, one must fully understand the correlation between chemistry, structure, particle size and processing. Among the broad classification of magnetic oxides, the spinel ferrites gain much importance because of their low cost, high magnetic permeability...

2017
Fernando Pedraza F. Pedraza

Upon the isothermal oxidation of an ODS FeAl Grade 3 intermetallic alloy, a structured oxide scale is developed between 800 and 950o C. TEM studies have revealed a three-layered structure with a top nanoequiaxed alumina, a central alumina and a bottom Fe-Al spinel. At these temperatures, aluminium outward diffusion does not seem to be suppressed neither by the spinel sub-layer nor by the yttria...

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