Mössbauer Effect Study of Natural Egyptian Chalcopyrite

Eissa, N. A.; Sallam, H. A.; El-Ockr, M. M.; Mahmoud, E. A.; Saleh, Sherif

doi:10.1051/jphyscol:19766167

Cited by 6 publications

(2 citation statements)

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“…Among the different forms of Cu-Fe-S nanocrystals, one can distinguish antiferromagnetic a-CuFeS 2 (tetragonal), [36][37][38] ferromagnetic b-CuFeS 2 (cubic) 36,39 and non-magnetic (down to 78 K) g-CuFeS 2 (tetragonal) 36 phases of chalcopyrite, ferromagnetic CuFe 2 S 3 (cubanite; orthorhombic) 40 and non-magnetic cubic form of cubanite, namely, isocubanite. 41 The point is how to distinguish between chalcopyrite (and its different phases) and cubanite (and its different phases).…”

Section: Magnetic Properties and Mossbauer Spectroscopymentioning

confidence: 99%

Non-injection synthesis of monodisperse Cu–Fe–S nanocrystals and their size dependent properties

Gabka

Bujak

Żukrowski

et al. 2016

Phys. Chem. Chem. Phys.

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It is demonstrated that ternary Cu-Fe-S nanocrystals differing in composition (from Cu-rich to Fe-rich), structure (chalcopyrite or high bornite) and size can be obtained from a mixture of CuCl, FeCl3, thiourea and oleic acid (OA) in oleylamine (OLA) using the heating up procedure. This new preparation method yields the smallest Cu-Fe-S nanocrystals ever reported to date (1.5 nm for the high bornite structure and 2.7 nm for the chalcopyrite structure). A comparative study of nanocrystals of the same composition (Cu1.6Fe1.0S2.0) but different in size (2.7 nm and 9.3 nm) revealed a pronounced quantum confinement effect, confirmed by three different techniques: UV-vis spectroscopy, cyclic voltammetry and Mössbauer spectroscopy. The optical band gap increased from 0.60 eV in the bulk material to 0.69 eV in the nanocrystals of 9.3 nm size and to 1.39 eV in nanocrystals of 2.7 nm size. The same trend was observed in the electrochemical band gaps, derived from cyclic voltammetry studies (band gaps of 0.74 eV and 1.54 eV). The quantum effect was also manifested in Mössbauer spectroscopy by an abrupt change in the spectrum from a quadrupole doublet to a Zeeman sextet below 10 K, which could be interpreted in terms of the well defined energy states in these nanoparticles, resulting from quantum confinement. The Mössbauer spectroscopic data confirmed, in addition to the results of XPS spectroscopy, the co-existence of Fe(iii) and Fe(ii) in the synthesized nanocrystals. The organic shell composition was investigated by NMR (after dissolution of the inorganic core) and IR spectroscopy. Both methods identified oleylamine (OLA) and 1-octadecene (ODE) as surfacial ligands, the latter being formed in situ via an elimination-hydrogenation reaction occurring between OLA and the nanocrystal surface.

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Section: Magnetic Properties and Mossbauer Spectroscopymentioning

confidence: 99%

Non-injection synthesis of monodisperse Cu–Fe–S nanocrystals and their size dependent properties

Gabka

Bujak

Żukrowski

et al. 2016

Phys. Chem. Chem. Phys.

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“…57 Fe Mössbauer spectroscopy has become an interesting tool in the determination of iron sites and in the assignment of the oxidation states of iron, which are factors of great geological consideration in the study of the evolution of plutonic rocks [2][3][4][5][6]. It was interested to apply the technique to an extrusive (volcanic) type that rapidly crystallized from magmas and to measure the extent of oxidation and cation ordering.…”

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confidence: 99%

Rhyolite–dacite–trachyandesite association: a Mössbauer spectroscopy study

Hassan

2009

Hyperfine Interact

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Three volcanic dykes, rhyolite, dacite and trachyandesite cutting a radioactive granite, located between Latitudes 22 • 47 396 -22 • 47 884 N and Longitudes 31 • 54 883 -31 • 54 894 E in the south Western Desert of Egypt were sampled and analyzed by X-ray diffraction, 57 Fe Mössbauer spectroscopy and chemical method. They are consisted of feldspar and quartz together with some paramagnetic minerals including aegirine plus minor riebeckite in the rhyolite; aegirine plus some riebeckite in the dacite; and riebeckite plus trace aegirine in the trachyandesite, respectively. The bulk content of iron in each dyke has characteristic ferric-quadrupole splitting and oxidation values: 0.29 millimeters per second (mm/s) and 100% for rhyolite; 0.31 mm/s and 82% for dacite; and 0.35 mm/s and 0.69% for trachyandesite. Variations in the quadrupole splitting have been attributed to changes from the local crystal chemistry, while the oxidation variations are source-related.Keywords Volcanic dykes · Aegirine · Riebeckite · Mössbauer · Egypt The rhyolite, dacite and trachyandesite are granite-rooted dykes with distinctive colors, brown, light green, and dark green, respectively. Each dyke is ∼0.5 m thick and a few meters long of a fine-grain material exhibiting microscopic fibrous structures. The total field gamma (γ )-ray radiation increases from the trachyandesite to the dacite, and to the rhyolite dyke. The latter has anomalously high radioactivity levels, but without any obvious radioactive mineralization. The major source

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