X-ray and Mössbauer study of rapidly solidified Ce20Fe80 ribbons; effect of the quenching rate

1994 ◽  
Vol 88 (1) ◽  
pp. 65-71 ◽  
Author(s):  
G. Roulin ◽  
J. Teillet ◽  
A. Fnidiki ◽  
B. Labulle ◽  
P. Ochin
Keyword(s):  
Mössbauer Study ◽  
Quenching Rate ◽  
X Ray ◽  
Rapidly Solidified

Microstructure of Nb3 (AlSiB) superconducting tapes with extremely high critical current densities

1989 ◽  
Vol 4 (3) ◽  
pp. 526-529 ◽  
Author(s):  
Mireille Treuil Clapp ◽  
Zhang Jian ◽  
Tariq Manzur
Keyword(s):  
Critical Current ◽  
Melt Spinning ◽  
Quenching Rate ◽  
Fine Grained ◽  
Annealing Conditions ◽  
Second Phases ◽  
Current Densities ◽  
Rapidly Solidified ◽  
Equiaxed Grains ◽  
A15 Phase

Alloys of Nb73Al12Si14.5B0.5 were rapidly solidified into amorphous ribbons using the melt spinning technique. These were isothermally annealed at temperatures ranging from 660 to 780 °C. The A15 phase began to crystallize at 700 °C and small amounts of second phases appeared at the higher temperatures. Crystallization was dependent on quenching rate as well as annealing conditions. Below 750 °C nucleation was nonuniform and was enhanced by surfaces and quenched-in nuclei. Above 750 °C nucleation became more uniform and completely crystalline ribbons with equiaxed grains ∼30 nm in diameter were obtained. These ultra fine grained ribbons had extremely high superconducting critical current densities of 8 × 1010 A/m2 and 5 × 1010 A/m2 at magnetic fields of 0.5 and 15 tesla, respectively, at 4.2 K.

scholarly journals Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Mineralogia ◽  
2013 ◽  
Vol 44 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Kamaleldin M. Hassan ◽  
Julius Dekan
Keyword(s):  
Optical Microscopy ◽  
Crystal Chemistry ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Oxidized Iron

AbstractOlivine basalts from southern Egypt were studied by 57Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe2+), and a weak ferric (Fe3+) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe3+/ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

scholarly journals X-ray diffraction analysis of the non-uniform microstructure of rapidly solidified AlSi alloys

1981 ◽  
Vol 37 (a1) ◽  
pp. C153-C153
Author(s):  
R. Delhez ◽  
Th. H. de Keijser ◽  
E. J. Mittemeijer ◽  
P. van Mourik ◽  
N. M. van der Pers
Keyword(s):  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uniform Microstructure ◽  
Rapidly Solidified

Mössbauer study of 50MeV Li3+ ion irradiated Mg0.9Mn 0.1InxFe2-xO4 ferrite

2003 ◽  
Vol 792 ◽  
Author(s):  
M. Singh ◽  
Anjana Dogra ◽  
Ravi Kumar
Keyword(s):  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Lattice Strain ◽  
Electronic Configuration ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Cubic Symmetry ◽  
X Ray ◽  
Anomalous Character ◽  
Super Exchange Interaction

ABSTRACTA series of samples of Mg0.9Mn0.1InxFe2-xO4 for x=0, 0.3, 0.5 were prepared by conventional solid-state technique. The spinel structure of this ferrite was confirmed by X-ray diffraction technique. The samples were irradiated with 50 MeV Li3+ ions with fluence 5×1013 ions/cm2. The Mössbauer studies were performed on unirradiated as well as on irradiated samples. Mössbauer study for unirradiated samples show insignificant variation of isomer shifts at both the tetrahedral and octahedral sites. On irradiation isomer shift changes from negative to positive values. This anomalous character of isomer shift after irradiation is due to a change in the electronic configuration of Fe3+ ions. The quadrupole splitting of unirradiated samples are negligibly small, indicates the presence of cubic symmetry at both the sites. On irradiation appreciable changes are observed in quadrupole splitting due to the presence of lattice strain. On irradiation super-exchange interaction energy is weakened which decrease the hyperfine field. PACS: 61.80, 76.80, 61.72

Pyrophosphates of Tetravalent Elements and a Mössbauer Study of SnP2O7

1975 ◽  
Vol 53 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Chung-Hsi Huang ◽  
Osvald Knop ◽  
David A. Othen ◽  
Frank W. D. Woodhams ◽  
R. Allan Howie
Keyword(s):  
Chemical Shift ◽  
Electric Field ◽  
Electric Field Gradient ◽  
The Other ◽  
Type I ◽  
Type Ii ◽  
Transition Elements ◽  
Mössbauer Study ◽  
X Ray ◽  
Ionic Compounds

Cubic M4+P2O7 pyrophosphates of Ti, Zr, Hf, Sn, and Pb have been examined by X-ray powder diffractometry and by infrared, Raman, and Mössbauer 119Sn spectroscopy. The tin compound appeared to be of Chaunac's type I (with P2O7 groups oriented at random) and could be converted to type II (with ordered P2O7 groups) by heating to high temperatures. All the other preparations were of Chaunac's type II. Evidence from lattice parameters and intensity features of the Raman spectra suggests that the cubic MP2O7 pyrophosphates fall in two groups, one containing the compounds of the typical elements (Ge, Sn, Pb) and the other, the compounds of the transition elements. No support has been found for the view that the P—O—P groupings of the pyrophosphate anion in these compounds are linear. The 119Sn chemical shift in SnP2O7 is only slightly less negative than the shift in CuSnF6.4H2O, which makes SnP2O7 one of the most ionic compounds of tetravalent tin known. The observed quadrupole splitting in the Mössbauer spectrum of SnP2O7 arises largely from the contribution of the valence term to the electric field gradient at the Sn atom.

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